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Exterior exposures of coatings on wood substrates
NATIONAL RESEARCH COUNCIL OF CANADA DIVISION OF BUILDING RESEARCH
EXTERIOR EXPOSURES OF COATINGS ON WOOD SUBSTRATES
by
H. E. Ashton
Internal Report No. 365 of the
Division of Building Research
OTTAWA October 1968
PREFACE
Application of organic coatings to exterior wood surfaces is an important aspect of Canadian building practice, especially on both coasts where timber is plentiful. Consequently, studies that would help the Division to give advice on problems that arise in this field have been part of the program of the Building Materials Section. Mr. J. Harris, who was the officer-in-charge of the Paint
Laboratory for some years, carried out much research on coatings applied to wood.
Laboratory studies on the properties of coatings indicated which types should give good performance. In the absence of re-liable or accepted accelerated tests it was necessary to confirm the laboratory results by natural exposure of the coatings. This report records the results of the different exposure tests.
Ottawa
October 1968
R. F. Legget Director
EXTERIOR EXPOSURES OF eOA TINGS ON WOOD SUBSTRATES
by
H. E. Ashton
In conjunction with laboratory studies on coating systems for wood, Mr. J. Harris (1) had many of the same materials exposed out-door s on various wood substrates. This report records the results of the different exposure tests.
MATERIALS
The generalized composition of the coatings which were ex-posed is given in Table I and, except for the commercial latex paints, their chief parameters are compared i.n Table II. Complete formu-lations of materials prepared in the DBR Paint Laboratory, including primers and a sealer, are given in Appendix A. The acrylic latex was purchased over a period of
zi
years so it is not known if the com-position had been changed between batches.The substrates used were white pine and red cedar siding, birch exterior grade plywood, tempered hardboard (masonite) and red cedar shingles. In most tests on siding the long dimension was in the horizontal direction and the siding was in the drop or cove shape. One year, siding was also exposed with grain arranged vertically and for this test tongue and groove siding was used. Most tests were conducted at the Division's Montreal Road exposure site, but three duplicate panels of one series were exposed in Halifax at the York Redoubt site. All panels were mounted vertically facing south.
Because the exposures were begun in different years and the program was modified as time progressed as the result of laboratory and exposure tests, all the different coatings were not exposed on all substrates. This procedure reduces the number of individual samples but makes analysis of the results much more complex. There were al-so differences in the application procedures with time. In most of the early tests the wood was sealed with two coats of clear alkyd sealer. In the later tests three coats of the finishes, regardless of type, were applied to bare wood. While this procedure may be regarded as placing
2
-all coatings on the same footing, it may have been unfair to those that were specifically designed for use over a primer. Except for the last exposure series in 1963, the first coat of the three coat system was generally reduced with 10-15 per cent thinner. The first coat of latex paints was not reduced because thinning cannot aid penetration of the binder which is dispersed, not dissolved, in water. Thinning would only reduce the already low dry film thickness of latex paints. The coatings exposed and their substrates are arranged in Table III in chro-nological order. Details of application such as primer used or amount of thinning are also given.
From 1956 to 1959 the white pine and red cedar siding was coat-ed before being fastencoat-ed to the exposure frame. Aluminum paint was applied to the backs and ends of the boards after application of the test material to the face. The boards were screwed to H-frames so that the backs were open to the weather.
After 1959, the siding was mounted before painting. The backs of the boards were not sealed but the ends were. The siding was nail-ed to 3/4 inch sheathing covernail-ed with sheathing paper. There was also wood sheathing on the back of the assembly and, for vertical siding, a water table at the bottom as shown in the diagram (Figure 1). Shingles, plywood and masonite were also applied over sheathing paper. The
sides of the frames and the sheathing on the back were coated with alumi-num paint. Except where noted, panels were coated in the laboratory. RESULTS
The exposure panels were rated periodically by various
ob-servers. The descriptions and ratings are given in Table IV in the same order as their exposure. Unfortunately, in many cases it has not been possible to find the earlier results in the records. For the final ex-amination in 1967 two observers rated the panels independently and then reviewed the results together to resolve disagreements. Ratings were made on the conventional scale of 10 to 0, where 10 is perfect condition and
°
is complete failure.It is diffic ult to present exposure results in a manner that readily enables comparisons to be made or meaningful conclusions to be reached. At any single observation time there may be reversals in ratings of different coatings. In the analysis of these exposure studies the ratings were first
3
-plotted against time. From the general trend, the times at which each system reached ratings of 8, 5 and 2 were determined and are given in Table V. The first moderate drop in appearance or the first isolated failures in protection are reflected in a rating of 8. Five represents the condition when most coatings require repainting but without extensive preparation of the substrate. Two indicates severe failure either of the coating or the underlying surface. With coatings that had long durability or which had been exposed for only a relatively short time it was necessary to extrapolate to the time required to reach the lower ratings. In some cases, therefore, the estimate is not very precise, especially for the rating of 2.
The graphs of performance v s , time in Appendix B show that some coatings quickly drop to a fairly low rating but then do not exhibit much change for some time. Straight white lead paint had this type of ex-posure history. Other coatings have a high rating for several years and then fail rapidly. In the third case, the rating decreases fairly uni-fonnly with time. In order to accommodate these three types of failure, the time to reach a rating of 5 was selected as being most representative of the performance of a coating.
Effect of Substrate
The years required for several finishes applied in 3 coats to hare substrates to reach the repaint condition are shown in Table VI. Based on these results, horizontal siding is one of the better wood sub-strates. Cedar shingles also have a high rating, but this conclusion is more tentative because only 3 coatings were tested on them. The rn ean for the same three materials on horizontal siding was 6.4 years, but
this is influenced by the high rating of the alkyd enamel. Naturally, more definite conclusions can be reached when there are several ex-posures which can compensate for an occasional erratic result.
As expected from enquiries received from the field, plywood had the lowest mean rating of the different wood substrates. The alkyd enamel, however, lasted 6 years on it and the isophthalic finish had a higher rating on plywood than on other substrates except for tempered hardboard and sealed horizontal siding.
Plywood might be expected to be a good substrate for painting because the perpendicular arrangement of the plies increases its sta-bility to dimensional changes caused by variations in moisture content.
4
-However, when care is not taken in cutting the veneers or when the face veneer is not oriented so that the side that was originally towards the outside of the tree is on the outside of the sheet (referred to in the trade as bark- side out or loose face in), plywood on exterior exposure is very prone to develop cracks known as checks. The means for preventing this have been known for some years (2-4). Nevertheless, because most plywood is used where appearance is not a factor, it is evidently considered not economically feasible to take the necessary steps to produce plywood that will not check.
When the face ply has the bark-side out, the outer layer of wood is in compression. When the loose side is out, the small cracks pro-duced in rotary cutting of the veneer are exposed under tension and are likely to crack even more when stressed from shrinking and swelling. Since the laying up of plywood occurs randomly, about half should have the preferred arrangement which may account for the variations in per-formance of coatings on plywood. In addition, because veneers are edge jointed to provide the necessary panel width, this variation in dura-bility commonly occurs on the same panel (Figure 2).
Tempered hardboard showed poorer results than expected, chiefly because the lower edge of the siding swelled and disrupted most coatings. Studies by the U. S. Forest Products Laboratory (5) have shown that in-creasing the resin content is one way to overcome the "edge flare" de-fect in particleboards. This may also be true for fiberboards. The more water resistant alkyd enamel gave very good service on this surface, as shown in Table VI and Figure 3.
The effect of mounting the siding in the horizontal or the vertical direction is shown in Table VII. With 6 different coatings applied to wood erected in both directions the mean for horizontal is higher than for vertical siding. The analysis of these results is complicated by two factors: the reversal in durability results of the alkyd compared to those for the other 5 finishes and the different methods of preparation used in the two series. If the alkyd results are deleted, then the vertical siding mean is higher. Finishes applied to the horizontal panels in the field had the first coat reduced 10 - 15 per cent with solvent, however, where-as they were unreduced when applied to vertical siding in the laboratory. Browne (6) showed in 1930 that reduction of oil paints was not beneficial to exterior performance and DBR work on clear finishes has shown that thinning the first coat merely reduces film thickness and subsequent
5
-durability. It is therefore difficult to conclude definitely that :mounting siding in any particular direction is a :more severe exposure of coatings. Differences Between Coatings
The results fro:m coatings that were applied to 4 or :more sub-strates are given in Table VIII. It can be seen that where there was a sufficient nu:mber of exposures to :make a reasonable co:mparison, the alkyd ena:mel gave the best over-all results. Comparison of the alkyd perfor:mance on other surfaces with other :materials indicates that the durability rating is higher on horizontal and lower on vertical siding than :might logically be expected.
The i s ophthalic alkyd finish ranked second in over -all perfor-:mance on 6 different surfaces. In s orn e cases because of :mildew growth it received a lower rating than it :might have fro:m the point of view of protection alone. The :mildewcide reco:m:mended in the original for:mula was not incorporated in the batch :made in the DBR Paint Laboratory SO
the :material :may be capable of better perfor:mance. For:mula 785, an alkyd finish, and 566, the standard oil paint, were si:milar in durability. The hiding pig:ment in the alkyd was anatase titaniu:m dioxide which chalks :much :more than the rutile used in the oil paint. The severe chalking lead-ing to :marked erosion of the fil:m probably contributed to the lower dura-bility of 785 co:mpared to that of the alkyd ena:mel.
The white lead in oil paint was quite inferior to rn o st of the other coatings, generally failing by checking. Even on plywood where the sub-strate failed leaving long thin strips, the re:maining paint was checked. Inclusion of zinc oxide in for:mula 843 did not noticeably i:mprove the per-for:mance. It is thus evident that the industry has produced coatings that are superior to those in co:m:mon use at the beginning of this century. The reputation for good durability that these old-ti:me paints still possess is apparently due more to fond recollection than to actual perfor:mance.
Latex paint, which is the other coating com:monly applied to wood siding in North America, was inferior to the oil paint. This result is contrary to rn o s t field experience and is probably due to application of the latex paint to unprimed wood. Acrylic latices at the ti:me these ex-posures began were not :made for use on bare wood. In recent years such ernul s ions have been introduced and better perfor:mance might be expected. In general, a latex paint should be used precisely as directed by the
6
-The PYA latex paint was not exposed long enough or under enough con-ditions to rnak e a valid c ornpa r i s on , It is understood, however, that rn o st coating rnariufa c tu r e r s in Canada prefer acrylics for use on ex-terior wood.
In the series 785, 786, 787, c ornpa r ing p igm ent and vehicle rnodific a ti.on s , it is again difficult to reach any conclusions because rn o r e than one factor was varied at a tirn e , Also, the numbe r of ex-posures of all three coatings was Lirrri te d, On bare wood the three were a lrn o st identical in pe rf o r maric e but on sealed wood there was a rria r k ad difference. It cannot be concluded on the basis of one ex-posure whether this difference was real or fortuitous. The r erria.r k . able irnp r ov erne nt in p e rf'o r rnaric e on sealed wood of the lead-free zinc-t.i.tan iurn oil-alkyd finish, 787, will be checked again.
The effect of sealing the wood before coating is shown in Table IX. Most coatings had iITlproved durability over sealed wood as m ight
be expected f r orn a s ornewhat higher total f i lrn thickness. Again the alkyd enamel exhibited a reversal of the general trend and this will also be rechecked on exposures that commence at the same time.
In the fir st exposure series oil paints 1- GP-2 8a, Types A and B, were applied to siding over primer l-GP-55b. The resultant durabilities were unexpectedly higher than in any subsequent exposures of Type B over white lead p r irn.e r or s e lfvp r irn ed, Although a single result is not conclusive evidence, there is a strong indication that superior performance is obtained if oil paint is applied over a properly formulated p r irn e r , Comparable results obtained by industry probably ledtothe adoption of special primers for house paints instead of self-priming.
Effect of Sites
Table X shows that in this very limited test, three coatings failed rn o r e rapidly at York Redoubt than at Ottawa. Most of our more extensive exposure studies have not shown this difference in severity between these two sites. Part of the discrepancy ITlay result f r orn the use of different ob servers except for the final examination.
SUMMARY
7
-a difficult m-ateri-al to p-aint s-atisf-actorily. An alkyd enamel and an isophthalic alkyd finish gave reasonable performance on this sub-strate.
Cedar shingles were somewhat less demanding on the three coatings applied to them than was hardboard. The latter swelled at the lower edges, cracking most systems except the alkyd enamel.
The alkyd enamel was best on most surfaces although it had poor durability on vertical siding. An isophthalic alkyd was next in over -all performance. The latex was generally poor, probably because it was applied to bare wood. The usual type of oil paint was intermediate to the enamel and the latex except on vertical siding, where it was best due to the unexplained low rating of the alkyd. Use of an oil primer markedly improved the performance of this oil paint on horizontal siding. Straight white lead was very poor on most sur-faces; on hardboard it had an unsatisfactory appearance in a few months and deteriorated to a rating of 5 in only two years (Figure 4). Application of two coats of sealer to siding appeared to improve the durability of most finishes but the exposures with and without sealer were started in different years.
On the basis of these exposures and previously reported labo-ratory tests (1), it is concluded that the use of alkyds on wood siding should receive more consideration than it has in the past. Many paint chemists have cautioned against blind acceptance of test fence
exposure results because there is no temperature or moisture gradient across the panels. In laboratory tests, however, alkyds have demon-strated good wet adhesion and have been reportedly used on houses in Norway where the climate is wet and in Australia where it is dry. It is thought, therefore, that their use for this purpose should be
re-examined in Canada. ACKNOWLEDGEMENT
These exposure studies were commenced by Mr. J. Harris, formerly Research Officer in charge of the Paint Laboratory. Thanks are due to Mr. R. C. Seeley who rated the panels and kept accurate records over the last 4 years. Mr. Seeley also prepared the exposure panels for the last 3 series.
8
-REFERENCES:
1. Harris, J. A Study of House Paint Properties. Canadian Paint
and Varnish, Vol. 37, No.2, p.22, No.3, p.42, 1963.
2. Batey, T. E. Minimizing Face Checking of Plywood. Forest
Products J., VoL V, No.5, p.277, 1955.
3. Yan, M.M. and W. G. Lang. Veneer Checking and Warping.
Canadian Woodworker, November 1958, p.20.
4. Keith, C. T. Surface Checking in Veneered Panels. Forest
Products J., Vol. XIV, No. 10, p.481, 1964.
5. Heebink, B. G. A Look at Degradation in Particleboards for
Exterior Use. Forest Products J. ,Vol. 17, No.1,
p.59, 1967.
6. Browne, F. L. Effect of Primer Reduction and Special Primers
Upon Paint Service, Ind. and Eng. Chemistry, Vol. 22,
TABLE I
Materials SUbjected to Exterior Exposure on Wood Substrates
Labora tory
Number
Type of vehicle
Main pigments
Classification of
coating
566
Linseed Oil
Lead, Zinc, Titanium
Oil Paint l-GP-28a Type
B568
Linseed Oil
Lead,
Zinc, Titanium
Oil Paint l-GP-28a Type
A659
Alkyd Resin
Titanium Dioxide
Alkyd Enamel
785
Alkyd Resin
Titanium, Talc
Alkyd Finish
786
Oil-Alkyd
Lead,
Zinc, Titanium
Alkyd Modified Oil Paint
787
Oil-Alkyd
Zinc, Titanium
Alkyd Modified Oil Paint
788
Isophthalic Alkyd
Titanium, Talc
Alkyd Finish
842
Linseed Oil
White Lead Carbonate
Lead in Oil Paint
843
Linseed Oil
White Lead, Zinc Oxide
Lead-Zinc
Oil Paint
11374
PVA Latex
Unknown
Latex Paint
11423 )
Acrylic Latex
Unknown
Latex Paint
TABLE II
Comparison of Coating Properties
I
566
568
659
785
786
787
788
842
843
Weight per gallon, liquid
17.40
17.45
12.49
14.42
18.02
16.74
14.55
23.04
19.51
Weight per solid ga 110n
20.26
20.38
16.77
16.60
20.65
19.14
16.89
27.33
23.05
Percent Pigment
61. 81
61.83
33.47
49.78
\I63.52
60.25
52.07
70.55
64.47
I
Percent non-volatile vehicle
27·44
27.42
36.82
36.22
27.27
29.51
33.17
21.64
25.79
Percent solids
89.24
89.25
70.29
86.00
90.79
89.76
85.24
92.19
90.26
P:V p.atio
2.25:1
2.25:1 0.91:1
1.37:1
2.33:1 2.04: ]
1. 57 : 1 3.26:1 2.5:1
PVC
%
33.6
33.25
18.66
30.07
35.59
34.76
32.36
30.98
29.23
TABLE III Coating Systnms ExposAo
Year PanelNo. ＭＭＭＭＭｾｩｄｩｾ｢ _
No. Type Subs tra te 1st Coat 2nd Coat 3rd 4th 5th 6th
"
1956 56-27 & 28 56-25 & 26 566 568 Oil Paint " nCedar &Pine Siding It n 578 Primer
"
"
566 thin. 51t 568 566 568 566 566 566 659 659 659 659 11374 11374 11374 -494 pro"
"
718"
""
"
718 Sealer"
""
"
Cedar & Pine Siding Oil Paint
566 58-41 &
42
58-39 & 659 Alkyd Enamel 40
58-37 & 1374 PVA Latex 38
1958
195959-41 &
42 785 Alkyd Finish Cedar &Pine
Sid ing 718 Sea ler 59-43 & 44 59-45 & 46 59-47 & 48 786 787 788 Oil-Alkyd " II Isophtha lie
"
"
" ""
"
""
"
"
"
718"
"
"
785 786 787 788 785 786 787 788 785 786 787 788 5661 Oil Paint 659 Alkyd EnamelI
785 Alkyd Finish 786 Oil-Alkyd 787" "I
788 Isophthalic 842 Lead in Oil 566 thin.101t 659 " " 843 thin.10-15% 11423"
1960 60-5 60-6 60-1 60-2 60-3 60-4 60-7 60-8 60-9 60-10 60-11 60-12 843 11423"
566 659 Oil Paint Acrylic Latex It " Oil Paint Alkyd EnamelPine & Cedar
"
"
" rt"
"
"
"
""
""
Pine &Cedar"
"
I, If"
"
It ft 566 659 785 786 787 788 842 ｴｨｩｮＮＱｏＭＱＵｾ tt " tr n ft " thin. 10-15"1. " It 566 659 785 786 787 788 842 843 11423"
566 659 566 659 785 786 787 788 842 843 11423"
566 659 Panels 60-1 to 60-8 were prepared on the fence in Sept. Panels 9 to 60-12 were prepared in the lab in October.Panels 60-1 to 60-8 were prepared on the fence in Sept. Panela 9 to 60-12 were prepared in the lab in October. The laat 3 were exposed in Halifax. 842 Lead in Oil 566 Oil Paint
"
"
"
785 Alkyd Finish " II II 11423 Acrylic Latex " " 11 788"
"
842"
785"
566"
659 11423"
566 659"
785 " 788 842"
11423"
"
"
"
"
"
"
"
"
""
"
"
"
"
"
"
""
"
11423"
566 thin.lO% f1 " " 842 659 785"
788 Plywood Masonite Plywood Masonite Plywood Masonite Plywood Masonite Plywood Masonite Plywood Masonite ""
"
788 Isophthalic " n 659 Alkyd Enamel " n " 61-1 61-9 61-2 61-11 61-6 61-8 61-5 61-7 61-3 61-10 61-4 61-12 1961 1963 63-1 63-2 63-3 63-4 63-5 63-6 63-7 63-8 63-9 566 659 788 842 843 11423"
659 566 Oil Paint Alkyd Enamel Isophthalic Lead in Oil Oil Paint Acrylic Latex " It Alkyd Enamel Oil Paint Vertical pine Siding"
"
"
"
"
" t1 ""
"
n " 566 659 788 842 843 11423"
659 566 566 659 788 842 843 11423"
659 566 566 659 788 842 843 11423"
659 566 Panels 1 to 63-6 were exposed in April. Panels 63-7 to 63-9 were ex-posed in December.TABLE IV
Exposure Results
Exposure Date Date
&Panel No. Examined 28 Sept.1956 15 May 1964 56-27 & 28 20 Oct.1965 28 Oct.1966 27 Oct.1967 Length of Exposure 7 yrs. 8 mos. 9 yrs. 1 mo. 10 yrs. 1 mo. 11 yrs. 1 mo. Description
Some cracks at ends and bottom edges of some boards. Marked chalking.
Up to 2" cracks on all boards. Peeling at ends of 3 boards, cracking in cove of one and at bottom of another board. Marked chalking. End cracks as before. 2 boards with cracking on bottom. Marked chalking.
End cracks as before. 3 boards with cracking in cove. One board cracking &peeling 25%. 4 with mildew. Chalking moderate - marked.
Rating 7 6 5 28 Sept.1956 56-25 &26 15 May 1964 20 Oct.1965 28 Oct.1966 27 Oct.1967 7 yrs. 8 mos. 9 yrs. 1 mo. 10 yrs. 1 mo. 11 yrs. 1 mo.
Fine cracks in coves and over most of sur-face. Slight dirt collection. Marked chalking.
1-1/2" cracks at ends. One board cracking in cove &one at bottom. Marked chalking. Cracking in all coves. Two boards cracking at bottom. Erosion and severe chalking. Cracking &peeling in coves &at edges. 3 boards cracking at bottom, 2 others fine crack-ing at bottom. Erosion and severe chalking.
6 5 3 + + + + -1 Aug.-1958 58-41 &42 1 Aug.1958 58-39 &40 6 Aug.1959 9 Nov.1959 9 Aug.1960 12 Sept.1961 15 May 1964 20 Oct.1965 28 Oct.1966 27 Oct .1967 6 Aug.1959 9 Nov.1959 9 Aug.1960 12 Sep.1961 15 May 1964 20 Oct.1965 28 Oct.1966 27 Oct.1967 1 yr. 1 yr. 3 mos. 2 yrs. 3 yrs. 1 mo. 5 yrs. 9 mos. 7 yrs. 3 mos. 8 yrs. 3 mos. 9 yrs. 3 mos. 1 yr. 1 yr. 3 mos. 2 yrs. 3 yrs. 1 mo. 5 yrs. 9 m05. 7 yrs. 3 mos. 8 yrs. 3 mos. 9 yrs. 3 mos. Moderate chalking.
Moderate chalking &trace of dirt collection. Moderate chalking &slight dirt collection. Cracking on one board. Moderate dirt· collection. Chalking moderate - marked. Slight cracks at edge of cove. Flaking one pine panel. Slight dirt collection. Marked chalking.
Cracking at cove edge 4 boards. Severe chalking.
Cracking in all coves and on face of 3 boards. Severe chalking.
Paint cracking &peeling in all coves. Cracking & peeling badly on face of one pine board. On one cedar board cracking to primer only. Severe chalking.
Trace chalking.
Trace chalking and slight dirt. Slight chalking &dirt collection. Chalking moderate - marked. Marked dirt collection.
Cracking in all coves. All faces good except one board. Marked chalking.
Cracking in coves - cedar few, pine 100%. Flaking on 2 boards. Darkening at bottom edge. Marked chalking.
Cracking in all coves &on face of 2 boards. Some mildew. Severe chalking.
Fine cracking in all coves. Cracking and flaking face and coves of 2 boards. Ckalking severe. 9.5 9 9 8.5 7.5 6 4 3 10 10 9.5 8 5 4 3.5 3
Exposure Date
&Panel No. ExaminedDate
Length of Exposure TABLE IV (Cont'd) Description ( 2) Rating 1 Aug.1958 58-37 &38 13 July 1959 59-41 &42 8 Aug.1959 9 Nov.1959 9 Aug.1960 12 Sep.1961 15 May 1964 9 Aug.1960 12 Sep.1961 15 May 1964 20 Oct.1965 28 Oct.1966 27 Oct.1967 1 yr. 1 yr. 3 mos. 2 yrs. 3 yrs. 1 mo. 5 yrs. 9 mos. 1 yr. 1 mo. 2 yrs. 2 mos. 4 yrs.lO mos. 6 yrs. 3 mos. 7 yrs. 3 mos. 8 yrs. 3 mos. Slight chalking. Moderate chalking.
Moderate - marked chalking. Cracking on 2 pine
and 1 cedar. Fine cracks on 2 cedar.
Cracking on 5 boards, fine cracks on other.
Peeling on one board. Marked chalking.
Marked cracking of wood. Flaking on one board
along grain. Heavy erosion and marked chalking.
Slight - moderate chalking.Marked dirt colI. Moderate chalking. Marked dirt collection. Few small cracks in wood at ends. Slight dirt
collection. Severe chalking.
Cracking at edge of cove on 4 board. Few cracks
on bottom edge of 2 boards. Severe chalking.
Wood cracking at cove edge except top board. Cracking and erosion bottom corners. Severe chalking.
Wood cracking in cove and at edge. Erosion on
face and heavy erosion at edges.
,10 9.5 7 4.5 2 9 8 8 7 6 4 13 July 1959 59-43 &44 9 Aug.1960 12 Sep.1961 15 May 1964 20 Oct.1965 1 yr. 1 mo. 2 yrs. 2 mos , 4 yrs.lO mos. 6 yrs. 3 mos.
Trace cracking on bottom end of lower board. 9
Slight - moderate chalking.
Marked cracking at end,of bottom board. Moder- 8
ate chalking. No dirt.
Cedar boards fine cracks in cove. Pine boards 6.5'
wood cracks at ends. No dirt. Moderate chalking.
Paint cracking &flaking in cove &on surface 4
of pine boards. Also end cracks in wood.
Marked chalking. 28 Oct.1966
27 Oct .1967
7 yrs. 3 mos. 8 yrs. 3 mos.
Cracking in all coves. Flaking on pine.
Marked chalking.
Cracking in all coves. Fine cracks on face of
pine boards. Marked chalking.
3 2 13 July 1959 59-45 &46 13 July 1959 59-47 &48 9 Aug.1960 12 Sep.1961 15 May 1964 20 Oct.1965 28 Oct.1966 27 Oct.1967 9 Aug.1960 12 Sep.1961 15 May 1964 20 Oct.1965 28 Oct.1966 27 Oct.1967 1 yr. 1 mo. 2 yrs. 2 mos. 4 yrs.lO mos. 6 yrs. 3 mos. 7 yrs. 3 mos. 8 yrs. 3 mos. 1 yr. 1 mo. 2 yrs. 2 mos. 4 yrs.lO mos. 6 yrs. 3 mos. 7 yrs. 3 mos. 8 yrs. 3 mos.
Slight - moderate chalking. 9.5
Moderate chalking. No dirt collection. 9.5
Moderate - marked chalking. No dirt collection. 9.5
Bright appearance.
Bottom board wood cracks one end. Marked chalking. 9
Few cracks in coves of 4 boards. Wood cracks at 8
end of bottom board. Marked chalking.
Cracking in all coves and cove edges of 2 boards. 6.5
Wood cracking at ends of bottom 2 boards. Bright
appearance. Marked chalking.
Moderate chalking. Marked dirt collection. 8.5
Moderate chalking. Marked - severe dirt colI. 8
Mildew on surface. Bottom board wood cracks at 7
end and minute blisters on bottom. Marked chalking
Mildew on all panels. Wood cracks at end of bottom 6.5
cedar &pine boards. Marked chalking.
Mildew slightly worse on bottom cedar &pine 6
boards. Marked chalking.
Mildew very dense on cedar, dense on pine. 5
Bottom cedar board badly cracked on bottom and fine paint cracks in cove. Moderate - marked chalking.
TABLE IV (Cont'd) (3)
Exposure Date
&Panel No.
Date Examined
Length of
Exposure Description Rating
9 Sept.1960 60-5 15 May 1964 20 Oct.1965 28 Oct.1966 27 Oct.1967 3 yrs. 8 mos. 5 yrs. 1 mo. 6 yrs. 2 mos. 7 :frs. 2 mos.
Few brown spots on bottom of pine board. Marked chalking.
Small cracks in coves of 3 boards. Wood crack-ing on one cedar board. Moderate chalking. Cracking on half of boards with few on rest. Marked chalking.
Fine cracking on all boards. 2 with flaking on summer wood. Severe chalking.
9 7.5 5.5 3 9 Sept.1960 60-6 15 May 1964 20 Oct.1965 28 Oct.1966 27 Oct.1967 3 yrs. 8 mos. 5 yrs. 1 mo. 6 yrs':' 2 mos. 7 yrs. 2 mos.
Panel in very good condition.
Mildew on 2 pine boards on bottom edge. Marked chalking.
Trace greying (mildew) on bottom 1/2" of boards. Severe chalking.
2 pine boards have mildew, other has cracking at bottom. Severe chalking.
10 8.5 8 7 9 Sept.1960 60-1 15 May 1964 20 Oct.1965 28 Oct.1966 27 Oct.1967 3 yrs. 8 mos. 5 yrs. 1 mo. 6 yrs. 2 mos. 7 yrs. 2 mos.
Small broken blisters on bottom of one pine board. Flaking from summer wood on another pine board. Marked chalking.
Erosion on all panels. Small cracks on 3 boards. Marked chalking.
Badly eroded. Marked chalking.
Badly eroded. Yellow stain on 2 cedar boards. Wood cracking on 2 pine boards. Moderate - marked chalking. 6.5 4 2 1 3 2 4 7 i f = -- -- -- -- -- -- -- -- --
--Bottom pine &cedar boards cracking &flaking at lower corners. Slight stain at cracks. Marked chalking.
Cracking &flaking at bottom edges of cedar. Cracking on surface of all boards. Wood cracking on one cedar board. Erosion on cove edge of another cedar. Marked chalking.
Cracking and flaking 100%. Marked chalking. Paint eroded on all panels, also flaking from summer wood. Two pine boards stained. Marked chalking. 3 yrs. 8 mos. 5 yrs. 1 mo. 6 yrs. 2 mos. 7 YrS' 2 mos. 28 Oct.1966 27 Oct.1967 20 Oct.1965 15 May 1964 9 Sept.1960 60-2 9 Sept.1960 60-3 15 May 1964 20 Oct.1965 28 Oct.1966 27 Oct.1967 3 yrs. 8 mos. 5 yrs. 1 mo. 6 yrs. 2 mos. 7 yrs. 2 mos.
Paint cracking at edges &ends of pine boards. Very good on cedar. Marked chalking.
Cracking on pine boards with flaking on 2. Some cracking in all coves. Wood cracking on bottom of one cedar board & end of one pine board. Marked chalking.
Cracking &flaking on pine. Erosion &wood crack-ing on cedar. Moderate - marked chalking.
Cracking, severe flaking & yellow stain on pine. Erosion with cracking on cedar. Moderate chalking.
7.5 4 2 1 9 Sept.1960 60-4 15 May 1964 20 Oct.1965 28 Oct.1966 27 Oct.1967 3 yrs. 8 mos. 5 yrs. 1 mo. 6 yrs. 2.mos. 7 yrs. 2 mos.
Small broken blisters on bottom & cove edge on pine. Cracking & flaking along grain. Mica evident. Marked chalking.
Erosion on all panels. Fine cracks in wood. Severe chalking.
Cracking &erosion on all boards. Marked chalking. Paint badly eroded. Wood cracking. Yellow stain on 2 pine boards. Moderate - marked chalking.
6
3
2 1
Flaking along grain on nearly allboards - worst on 4
2 cedar. Brcwn stain in film on bottom 2 cedar
boards. Severe chalking.
Whitest of 3(10,11 & 12) but starting to erode. 7
Small areas of peeling &flaking. Few cracks in wood.
Paint flake& off in spots & eroded generally. 4
Badly eroded showing grain pattern. Heavy cracking 1
on pine boards, fine cracking on cedar.
Very fine cracking on all boards, heavier in coves. 4.5
Cracking & slight flaking over summer wood on 1
pine and 2 cedar. Slight chalking.
Surface cracking allover. Flaking on 3 boards 3
&at edge of 2 more. Slight - moderate chalking.
Paint eroded and wood badly cracked on all. 2
Marked - severe chalking.
Paint flaking on summer wood. Checking & flaking 1
in cove on one board. Severe chalking.
Exposure Date Date Length of
&Panel No. Examined Exposure'
9 Sept.1960 15 May 1964 3 yrs. 8 mos.
60-7
20 Oct.1965 5 yrs. 1 mo.
28 Oct.1966 6 yrs. 2 mos.
27 Oct.1967 7 yrs. 2 mos.
9 Sept.1960 15 May 1964 3 yrs. 8 mos.
60-8
20 Oct.1965 5 yrs. 1 mo.
28 Oct.1966 6 yrs. 2 mos.
27 Oct.1967 7 yrs. 2 mos.
20 Oct.1960 15 May 1964 3 yrs. 7 mos.
60-9
Removed in July 1964
29 Nov.1960 8 Nov.1962 1 yr. 11 mos.
60-10
15 Oct.1963 2 yrs.ll mos.
4 Jan.1966 5 yrs. 1 mo.
TABLE IV (Cont'd)
Description
Fine checking over all panels. Flaking along
grain & broken blisters on one cedar board. Trace chalking.
Checking &erosion 100%. Wood cracking on all
boards. Moderate chalking.
Badly eroded 2 pine boards. Wood badly cracked
on all. Moderate chalking.
Paint gone from all summer wood. Badly checked
on rest. Slight - moderate chalking.
Rating 4
2.5
2
1
29 Nov.1960 8 Nov.1962 1 yr. 11 mos. Few isolated spots of flaking. Several wood
60-11 cracks. Some dirt collection.
15 Oct.1963 2 yrs .11 mos. Some flaking on pine. Better condition than
60-10.
4 Jan.1966 5 yrs. 1 mo. Flaking at bottom of pine boards. Cracking in
cove of 2 cedar boards. Wood cracking on one
pine. 8 7 5 29 Nov.1960 ＶＰＭｾＲ 27 June 1961 61-1 27 June 1961 61-9 8 Nov.1962 15 Oct.1963 4 Jan.1966 15 May 1964 20 Oct.1965 28 Oct.1966 27 Oct.1967
r
15 May 1964I
20 Oct.1965 28 Oct.1966 27 Oct.1967 1 yr. 11 mos. 2 yrs.11 mos. 5 yrs. 1 mo. 2 yrs.ll mos. 4 yrs. 4 mos. 5 yrs. 4 mos. 6 yrs. 4 mos. 2 yrs.ll mos. 4 yrs. 4 mos. 5 yrs. 4 mos. 6 yrs. 4 mos.Highest gloss but streaks of dirt. Best of 3 at Halifax.
Some black spots (mildew) on 2 pine boards. Few
cracks on bottom edge of other pine board. Very good condition on all cedar boards.
Surface of plywood cracked over 40-50% of area. Marked chalking.
Plywood cracking 100%. Heavy flaking along cracks
and at bottom. Severe chalking.
Cracking &flaking 100% of area. Severe chalking. Paint in long narrow pieces due to manner of wood
cracking. Severe chalking.
Lower edges of each masonite siding swollen due to
water. Paint cracking with some peeling in these
areas. Moderate dirt collection. Marked chalking.
Cracking &flaking up to 3" from bottom edges. Some cracking on remainder. Moderate - marked chalking.
Cracking &flaking 50% of panel. Marked chalking. Cracking &flaking 75% of panel. Marked chalking.
9 8 7.5 4 2 1 0.5 7 4 3 2
Exposure Date & Panel No.
Date Examined Length of Exposure TABLE IV (Cont'd) Description (5 ) Rating 27 .June 1961 61-2 27 .June 1961 61-11 27 .Iu ne 1961 61-6 15 May 1964 20 Oct.1965 28 Oct.1966 27 Oct.1967 15 May 1964 20 Oct.1965 28 Oct.1966 27 Oct.1967 15 May 1964 20 Oct.1965 28 Oct.1966 27 Oct.1967 2 yrs.11 mos. 4 yrs. 4mos. 5 yrs. 4 mos. 6 yrs. 4 mos. 2 yrs.ll mos. Ij yrs. 4 mos. 5 yrs. 4 mos. 6 yrs. 4 mos. 2 yrs.ll mos. 4 yrs. 4 mos. 5 yrs. 4 mos. 6 yrs. 4 mos.
Few cracks at bottom of panel with discoloration
there. Marked chalking.
Bottom cracks up to 2" long. Several small cracks
on remainder. Marked chalking.
Cracks at bottom up to 3". Fine cracks in center
and at right bottom. Marked chalking.
Cracks at bottom up to 3" long. Fine cracks on
right 40% of panel. Film adhering well and good
gloss. Marked chalking.
Two panels 1/2" swelling of board & slight dis-coloration. Slight dirt collection &moderate chalking.
Swelling at bottom 3/4" with some cracking and
darkening there. Marked chalking.
Bottom edges swollen up to 1". Grey and wrinkled
in this area. Marked chalking.
Bottom edges swollen, dirty and wrinkled up to 1". Marked chalking but good gloss under chalk.
Fine cracks in center 1/3 of panel. Larger cracks
at bottom and along sides. Severe chalking.
Paint eroding. Cracking over 80% of panel. Black
areas near bottom. Marked chalking.
Paint eroded. Wood badly cracked. Black area
50%. Marked chalking.
Film badly eroded. Wood badly cracked.
9 7 6 4.5 9 8.5 8 7.5 6 3 2 1 , r -27 .June 1961 15 May 1964 61-8 20 Oct.1965 28 Oct.1966 27 Oct.1967 27 .June 1961 15 May 1964 61-5 20 Oct.1965 28 Oct.1966 27 Oct.1967 27 .June 1961 15 May 1964 61-7 20 Oct.1965 28 Oct.1966 27 Oct.1967 2 yrs.ll mos. 4 yrs. 4 mos. 5 yrs. 4 mos. 6 yrs. 4 mos. 2 yrs.ll mos. 4 yrs. 4 mos. 5 yrs. 4 mos. 6 yrs. 4 mos. 2 yrs. 11 mos. 4 yrs. 4 mos. 5 yrs. 4 mos. 6 yrs. 4 mos.
Lower edges of boards swollen up to 1" with
dis-coloration. Marked chalking.
Bottom edges swollen up to 1" with film cracking
and slight discoloration. Marked chalking.
Paint eroding at ends &bottom of each board. Marked chalking.
Film eroded at ends &bottom and some in center .
.Also yellow stain in center. Marked chalking.
Film cracks at bottom 2". Good condition. Moderate chalking.
Cracks at bottom up to 3" long. 4 cracked areas
scattered over panel. Moderate chalking.
Cracks at bottom up to 4". 10 patches of fine
cracks. Mica evident. Marked chalking.
Cracks at bottom up to 4" long. 15 patches of fine
cracks. These areas appear dark. Severe chalking.
Bottom edges swollen up to 1". Grey &wrinkled in
this area. Mica evident. Slight chalking.
Bottom edges swollen &grey up to 1-1/2". Moderate chalking.
Bottom edges swollen, grey &wrinkled up to 2" and 1" on one side. Mica evident. Marked chalking. Bottom areas swolle'n, grey & wrinkled up to 2-1/2".
Dense ｾｲ･ｹ specks (mildew). Severe chalking.
B 7.5 5 3 9 6 5 4 8 7 6 4.5
Exposure Date
&Panel No. 27 June 1961 61-3 Date Examined 15 May 1964 20 Oct.1965 28 Oct.1966 27 Oct.1967 Length of Exposure 2 yrs.ll mos. 4 yr s . 4 mos. 5 yrs. 4 mos. 6 yrs. 4 mos. TABLE IV (Cont'd) Description
Plywood cracking 100% of panel. Film checking
between cracks 100%. Marked erosion but only slight
chalking.
Paint eroded to show grain. Fine surface cracking
of wood 100%. Slibht - moderate chalking.
Paint badly eroded. Plywood cracked over all area.
Paint almost completely gone. Fine cracks over all
wood. ( 6) Rating 4 2 1 o
Completely eroded except as above. Last areas of paint checked. Marked chalking. overlaps. Dark 27 June 19(.1 61-10 15 May 1964 20 Oct.1965 28 Oct.1966 27 Oct.1967 2 yrs.ll mcs . 4 yrs. 4 mos. 5 yrs. 4 mos. 6 yrs. 4 mos. Paint der. Paint Paint areas
eroding off 80% of boards; ｣ｨ･｣ｫｩｮｾ on
remain-Slight chalking.
eroded along brush marks. badly eroded except under on grey substrate. 3 2 1 o 27 June 1961 15 May 1964 61-4 20 Oct.1965 28 Oct.1966 27 Oct.1967 2 yrs.ll mos. 4 yrs. 4 mos. 5 yrs. 4 mos. 6 yrs. 4 mos.
Heavy wood cracking on one side of panel. Fine film 4
cracking on rest of panel. Marked chalking.
Cracking over all panel. Erosion over 75%, flaking 2
over badly cracked wood. Marked chalking.
Panel warped. Wood cracking worse on one side. 1.5
Flaking on 40%. Severe chalking.
One-third of paDel badly cracked &peeling. Remainder 1 fine cracks and badly eroded.
' 1 / + , , -27 June 1961 61-12 22 April 1963 63-1 15 May 1964 20 Oct.1965 28 Oct.1966 27 Oct.1967 15 May 1964 20 Oct.1965 28 Oct.1966 Oct.1967 2 yrs.ll mos. 4 yrs. 4 mos. 5 yrs. 4 mos. 6 yrs. 4 mos. 1 yr. 1 mo. 2 yrs. 6 mos. 3 yrs. 6 mos. 4 yrs. 6 mos.
Mottled effect over panel. Fine cracks ovei fibres.
Marked chaIkinI';.
Erosion over much of panel. Film cracking over
fibers. Severe chalking.
Erosion and cracking 100%. Severe chalking.
Paint badly eroded. Flaking along brush marks.
Stain over 3 knots. Slight dirt collection and
chalking.
3 knots showing. Few cracks at bottom up to 2". One board 5" cracks &stain at bottom. Marked chalking. 3 knots showing &purple stain from mildew near water table. Marked chalking.
Cracking over 3 knots. Some erosion. Few dark
patches may be mildew. Marked chalking.
5 3 2 1 9.5 8 7.5 7 22 April 1963 15 May 1964 63-2 20 Oct.1965 28 Oct.1966 27 Oct.1967 1 yr. 1 mo. 2 yrs. 6 mos. 3 yrs. 6 mos. II yrs. 6 mos.
Stain over 3 knots. Few cracks at bottom up to 3". Moderate dirt collection and trace chalking. Cracks at bottom from 1/2 to 5". Two boards grey
areas at bottom (mildew). Slight - moderate chalking.
All boards cracked at bottom. Two boards dark area
under film. Good gloss under dirt and chalk.
Marked chalking.
Black around cracks at bottom. Two areas cracking &
micro flaking. Two areas dark under rilm. Good
gloss, severe chalking.
8.5 7 6 4.5 ＭＭＭＭｾＭＭＭＫＭＭＭＭＭ｟｟｟ＫＭＭＭＭＭＭ｟ＫＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭｴＭＭＭＭ 22 April 1963 15 May 1964 63-3 20 Oct.1965 1 yr. 1 mos. 2 yrs. 6 mos. 1 knot showing. 1 knot showing. Severe chaIkinf';.
One crack at bottom. Severe chalking. 9
Exposure Date Date & Panel No. Examined
63-3 (Contd) 28 Oct.1966 27 Oct.1967 Length of Exposure 3 yrs. 6 mos. 4 yrs. 6 mos. TABLE IV (Cont'd) Description
Mica evident. Purple-grey scains bottom of 2
boards and top of third. Severe chalking.
Paint eroding at sides and ends. Mildew present.
One board cracked. Severe chalking.
( 7) Rating 6.5 5 22 April 1963 15 May 1964 63-4 20 Oct.1965 28 Oct.1966 27 Oct.1967 1 yr. 1 mo. 2 yrs. 6 mos. 3 yrs. 6 mos. 4 yrs. 6 mos.
Stain over 2 knots. Slight discoloration at bottom.
Slight chalking.
One board badly cracked; others few cracks at bottom.
Fine checking of paint. Slight chalking.
One board badly cracked. Paint has checked and is
eroding. Slight chalking.
Paint has checked - not any worse over knots. Fine
cracks in wood except 2 boards with heavy cracking. Slight chalking. 8 6 5 ＭＭｾｾｾＭｾ｟｟｟ｴｾｾｾｾｾＫＭｾｾｾｾｾｾｴＭＭｾｾｾｾＭｾＭＭＭｾＭｾｾＭｾＭｾｾＭＭＫＭＭＭ 200ct.1965 28 Oct.1966 27 Oct.1967 1 yr. 1 mo. 2 yrs. 6 mos. 3 yrs. 6 mos. 4 yrs. 6 mos.
Knots showing. 2 boards cracking at bottom. Slight 8.5
erosion but no chalking evident.
Flaking at 3 knots. Some erosion at bottom. Slight 7
surface cracking and chalking.
Paint eroding &.cracking on edges of 3 boards. Wood 6
cracking at bottom of 2 boards. Flaking around knots.
Slight chaLk l ng .
Paint eroded from 3 boards leaving fine cracks in
wood. 2 boards heavy crackinc at bottom, one with
stain. Slight chalking.
ＭＭＭＭＭｾＭｾＭＭＭ _ . _ + 1 + -22 April 1963 15 May 1964 63-6 20 Oct.1965 Oct.1966 27 Oct.1967 1 yr. 1 mo. 2 yrs. 6 mos. 3 yrs. 6 mos. 4 yrs. 6 mos.
Stain over 3 knots. One board cracked at bottom
Moderate chalking.
3 knots showing. Cracks at bottom up to 3". Severe chalking.
One board split full length with mildew along
edges. 3 boards cracked at both ends. Severe
chalking.
Boards cracked at top & bottom, one full length.
Heavy mildew one board, some on 2 others. Some
erosion. Severe chalking.
9 8 6 4.5 3 Dec. 1963 63-7 15 May 1964 200ct.1965 28 Oct.1966 27 Oct.1967 5 mos. 1 yr. 11 mos. 2 yrs.ll mos. 3 yrs.ll mos.
Slight stain especially at side and bottom of each
shingle. No chalking.
Brown stain showing at edges of shingles. Severe
chalking.
Slight stain still evident. Rough peaks of shingles
evident. Severe chalking.
Heavy brown stain from shingles. Severe chalking.
9 8.5 8 6 ＭＭＭＭＭＭＫＭＭＭＭＭＭＭＫＭＭＭＭＭＭＫＭＭＭＭＭＭＭＭＭｾＭＭＭＭＭＭＭＭＭＭＭＭ｟｟｟ｴＭＭ 3 Dec.1963 63-8 15 May 1964 20 Oct.1965 28 Oct.1966 27 Oct.1967 5 mos. 1 yr. 11 mos. 2 yrs.ll mos. 3 yrs.llmos.
Very good gloss. Panel excellent.
Good gloss. Knots appear darker. Trace chalking.
Good gloss. Rough peaks of shingles evident.
slight chalking. Panel excellent.
Wood grain evident. One knot has cracked film.
Moderate chalking. 10 9 9 8 5 mos. 3 Dec.1963 63-9 15 May 1964 ,20 Oct.1965 28 Oct.1966 27 Oct.1967 1 yr. 11 I 2 yrs.ll 3 yrs.11 I mos. mos. mos. Trace chalking. Slight chalking.
Stain over 5 knots. Marked chalking.
Cracks over 5 knots. Film cracking on most shingles.
Fairly bright appearance from severe chalking.
10 10
9 5
TABLE V
Years to Attain Given Rating
I
Horizontal Vertical Cedar Birch Tempered
NRP
Coating System Siding Siding Shingles Plywood Hardboard
No.
- -
- - --
- - ｾＭＭＭＭＭＭＭ - - - - - - - --8
5
2
8
5
2
8
5
2
8
5
2
8
5
2
566
3
coats4.
e
6.3
7.5
2.5
I
>8
3.3
3.9
4.3
1.0
2.4
4.3
1.9
3.8
6.3
3
coats+
primer4.5
7.7
9.4
+ 2
coats sealer-
-
-
-
-
-
-
-
-
-
-
-2
coats+ 1
primer5.7 10.1
12.4
-
-
-
-
-
-
-
-
-
-
-
-3
coats,exp.Halifax1.9
5.1
----g--
-
-
-
-
-
-
-
-
-
-
-
-
-568
2
coats+ 1
primer4.3
9.0
- -11. 8
--
-
-
-
-
-
-
-
-
-
-659
3
coats6.1 10
>11
1.5
4.2
6.5
3.9
I
->8
3.6
6.0
-
8
5.3
-8
>9
3
coats+ 2
sealer3.1
5.8
11
-
-
-
-
-
-
-
-
-
-
-
-3
coats,exp.Halifax2.9
I
->8
-
-
-
-
-
-
-
-
-
-
-
-785
3
coat s2.1
4.5
6.1
-
-
-
-
-
-
1.4
3.4
5.3
2.9
5.3
--
6.8
3
coats+ 2
sealer2.2
7.8
2-
-
-
-
-
-
-
-
-
-
-
-
-786
3
coats2.4
4.6
7.1
-
-
-
-
-
-
-
-
-
-
-
-3
coats+ 2
sealer2.2
5.6
8.3
-
-
-
-
-
-
-
-
-
-
-
-787
3
coats3.0
4.6
6.1
-
-
-
-
-
-
-
-
-
-
-
-3
coats+ 2
sealer7.3
9.2
>10
-
-
-
-
-
-
-
-
-
-
-
-788
3
coats1.8
4.1
6.1
2.0
4.3
6
-
-
-
3.4
5.3
8
2.9
6.0
8
3
coats+
2
sealer2.2
8.3
-10
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-842
3
coats1.2
3.0
6.1
1.0
3.5
-
6
-
-
-
1.0
2.4
4.3
0.8
2.0
4.3
843
3
coats1.3
3.3
6.1
1.5
4.0
-
6
-
-
-
-
-
-
-
-
-11374 3
coats+ 2
sealer1.7
2.9
5.8
-
- --
-
-
- --
-
-
-11423 3
coats1.2
3.0
5
2.5
4.2
6
2.9
4.2
5
1.0
2.4
4.3
1.2
2.9
5.3
3
coats,exp.Halifax1.3
2.6
"If.
4
-
-
-
-
-
- --
-
-
-
-
-
-
TABLE VI
3 Coats on Unsealed Substrate (years to reach rating of 5)
Wood Substrate Substrate
Substrate 566 659 788 842 11423 Mean 785 Mean
Horiz. Siding 6.3 10 4. 1 3.0 3.0 5.3 4.5 5.2 Vertical
"
7 4.2 4.3' 3.5 4.2 4.6-
4.6 Plywood 2.4 6.0 5.3 2.4 2.4 3.7 3.4 3.6 Hardboard 3.8 8 6.0 2.0 2.9 4.5 5.3 4.7 Coating Mean 4.9 7. 1 4.9 2.7 3. 1-
4.4 -Shingles 3.9 7-
-
4.2 5.0-
5.0 Coating Mean 4.7 7.0 4.9 2.7 3.3-
4.4 -TABLE VIIEffect of Siding Direction (years to reach rating of 5)
Material Coating
Applied Horizontal Vertical Mean
566 6.3 7 6.7 659 10 4.2 7. 1 788 4. 1 4.3 4.2 842 3.0 3.5 3.3 843 3.3 4.0 3.7 11423 3.0 4.2 3.6 Direction Mean 5.0 4.5
-Mean with 3.9 4.6 -out 659-TABLE VIII
Durability Results of Coatings Applied to Four or More Substrates
(years to reach rating of 5)
Lab. No. Horizontal Horizontal Tempered
of Siding Siding Vertical Hard- Coating
Coating Unsealed Sealed Siding Shingles Plywood board Mean
566 6.3 7.7 7.0 3.9 2.4 3.8 5.2 659 10.0 5.8 4.2 7.0 6.0 8.0 6.8 785 4.5 7.8
-
- 3.4 5.3 5.25 788 4. 1 8.3 4.3-
5.3 6.0 5.6 842 3.0-
3.5-
2.4 2.0 2.7 11423 3.0-
4.2 4.2 2.4 2.9 3.3 TABLE IXEffect of 2 Coats of Sealer (Horizontal Siding) (years to reach rating of 5)
Material Not Sealed Coating
Applied Sealed Mean
566 6.3 7.7* 7.0 659 10.0 5.8 7.9 785 4.5 7.8 6.2 786 4.6 5.6 5. 1 787 4.6 9.2 6.9 788 4. 1 8.3 6.2 Treatment Mean 5.7 7.4
-TABLE XEffect of Exposure Site (years to reach rating of 5)
Material York Coating
Applied Ottawa Redoubt Mean
566 6.3 5. 1 5.7
659 10.0 7.0 8.5
11423 3.0 2.6 2.8
Site
Mean 6.4 4.9
%
SHEATHING
ｾＭＲＧＱX 4" FRAME
u -__SHEATHING
PAPER
TEST PANEL
.--WATER TABLE
(on panels with
vertical siding
J
&.;IIiIo. , - •
-o
Figure 2 . - Different performance of latex paint on same plywood panel. C r a c k i n g and peeling on left quarter; erosion on centre; cracking and erosion on strip at right . (4 years ' exposure)
Figur e 3 . Alk yd enamel on tempered hardboard, a ft e r 6 ye a r s ' e x posu re. (Stre ak s are bru sh hair s l e ft in c oa t ing ).
Figu r e 4. White l e ad in o il o n t emper ed h ardbo ard a ft e r 6 year s' e x pos u re . (Paint r e m a in s only u nder l ap s and few i s ola t ed s pots ).
APPENDIX
AFORMULATION OF COATINGS SUBJECTED TO NATURAL WEATHERING
NRP Number:
566
568
Type:
Oil Paint
Oil Paint
Ingredients
Ib.per
parts by
Ib.per
parts by
100 gal.
*
wt.
100 gal.
wt.
Anatase Titanium Dioxide
-
-
107
6.15
Rutile Titanium Dioxide
200
11. 50
-
-Extended Titanium Dioxide
-
-
321
18.45
White Lead Carbonate
268
15.42
268
15.41
Zinc Oxide
268
15.42
268
15.41
Talc - Asbestine 3X
334
19.21
107
6.15
Bentone 34
4.5
0.26
-
-Aluminum Stearate
-
-
4.5
0.26
Alkali RefinedLinseed Oil
334
19.21
334
19.20
Z-3 Bodied Linseed Oil
143
8.22
143
8.22
Mineral Spirits
175
10.07
175
10.06
24% Lead Naphthenate
6.5
0.37
6.5'
0.37
6% Cobalt Naphthenate
5.5
0.32
-
-6% Manganese Naphthenate
-
-
5.5
0.32
1738.5
100.00
1739.5
100.00
NRP Number:
659
785
Type:
Alkyd Enamel
Alkyd Finish
Anatase Titanium Dioxide
-
-
290
20.06
Rutile Titanium Dioxide
420
33.47
-
-Talc - Ny tal 300
-
-
429.5
29.72
100% Alkyd Resin Aroplaz 1271
-
-
523.5
36.22
70% Alkyd Resin Durap1ex D65A
660
52.59
-
-Mineral Spirits
161
12.83
194.5
13.46
24% Lead Naphthenate
9.6
0.77
4.5
0.31
6% Cobalt Naphthenate
2.8
0.22
0.17
0.01
6% Manganese Naphthenate
-
-
1. 78
0.12
Anti-Skinning Agent
1.5
0.12
1.5
0.10
1254.9
100.00
1445.45
100.00
NRP Number:
842
843
Type:
Lead in Oil
Lead-Zinc in Oil
White Lead Carbonate
1630
70.55
756
38.68
Zinc Oxide
-
-
378
19.34
Talc - Ny tal 300
-
-
126
6.45
Alkali Refined Linseed Oil
500
21. 64
504
25.79
Mineral Spirits
166.5
7.21
176.5
9.03
24% LeadNaphthenate
10.1
0.44
10.1
0.52
6% Cobalt Naphthenate
3.9
0.17
3.8
0.19
2310.5
100.01
1954.4
100.00
A - 2
NRP Number:·f 786 787
Type: Alkyd Modified Pnt Alkyd Modified Paint
Ingredients lb.per 100 gal. parts by lb.per wt. 100 gal. parts by wt. Anatase Titanium Dioxide
Zinc Oxide
Leaded Zinc Oxide Talc - Nytal 300
100% Alkyd Resin - Aroplaz 1271 Alkali Refined LinseedOil
Mineral Spirits 24% LeadNaphthenate 6% Cobalt Naphthenate 6% Manganese Naphthenate Anti-Skinning Agent 171 575 400 238 254 158.5 4.15 0.16 1. 65 1.8 9.48 31. 87 22.17 13.19 14.08 8.78 0.23 0.01 0.09 0.10
175
380 465 256.5 243 165.5 4.25 0.17 1.71 1.7 10.34 22.45 27.47 15.15 14.35 9.78 0.25 0.01 0.10 0.10 1804.26 100.00 1692;83 100.00 NRP Number: Type: 578 Oil Primer 788Isopthalic Alkyd Fin. Anatase Titanium Dioxide
Rutile Titanium Dioxide White Lead Carbonate Talc - Nytal 300 325 Mica
Bentone 34'
100% Isophthalic Alkyd Raw Linseed Oil
Q
Bodied Linseed Oil Z-3 Bodied Linseed Oil Mineral Spirits 24% Lead Naphthenate 6% Cobalt Naphthenate 6% Manganese Naphthenate 4% Calcium Naphthenate 142.5 475 332 501 216 15.2 3.8 1685.5 8.45 28.18 19.70 29.72 12.82 0.90 0.23 100.00 240 60 390 60 3.6 360 120 192 9.6 4.8 2.4 4.8 1447.2 16.58 4.15 26.95 4.15 0.25 24.87 8.29 13.27 0.66 0.33 0.17 0.33 100.00 I + + H l . . . -NRP Number:Type: White Lead Primer
718
Clear Alkyd Sealer White Lead Carbonate
Raw Linseed Oil
60% Alkyd Resin Glyptal G2475 Mineral Spirits 24% Lead Naphthenate 6% Cobalt Naphthenate 960 785 24.4 1769.4 54.26 44.36 1. 38 100.00 350 490 3.5 1.4 844.9 41. 43 57.99 0.41 0.17 100.00
8
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6 c 4 2 E Posu r es Siding x ts Sealer 2 Coa 3 Coats Over din Ottawa 3 Coats Exposed in Halifaxo Expose 'd'ng • 3 Coats Vertical SI I c 3 Coats on S rf aces Other u on Plywood • 3 Coats Masonite 6 3 Coats on Shingles 6 3 Coats on 2 YEA RS EXPOSURE,
2 Coats Over I-GP-SS Primer • 3 Coats Over White Lead Primer
and 2 Coats Sealer
o 3 Coats I-GP-28 Type B
n 3 Coats on Vertical Siding • 2 Coats 1- GP-28 Type A Over
1- GP-55 Primer 2 3 1 8 9 10 7
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2 4 6 EXPOSURE, YEARS 8 10 1210 9 8 7 ｾ 6 cc <I: ｾ 4 o 3 2 1
PVA Over 2 Coats Sealer
.l Acrylic 3 Coats on Siding,Ottawa o Acrylic 3 Coats on Siding,Halifax n Acrylic 3 Coats Vertical Siding
x Acrylic 3 Coats on Shingles
10 8 4 2
o
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& 11423 Acrylic Latex
8 6 EXPOSURE, YEARS 4
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0 fJ 0 2 4 6 8 10 12 EXPOSURE, YEARS 1 0 . . . . " . . . - - - , r - - - , - - - . - - - . - - - , - - - , 9 7 8 I -<l: Ct: >-I - 5 <.::> z 6566 Oil Paint • 659 Alkyd Enamel • 786 Oil-Alkyd .842 Lead in Oil
a 843 Lead-Zinc Oil Paint
-.
•
7 9 8 10 c:.::> 6 z l -e:( a::: >-... 5 ....J a::l e:( a::: ;:) 4•
Q-.
3ｾｾ
2-,
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o
2 4 6 EXPOSURE, YEARS 8 10 1210 Vertical NRP Cedar 9 Si di n g NO. Shingles 566
•
•
659•
0 11423 x 8 0 843 7 <.:l 6 z l --c 0::: >-I - 5 ｾ co e( 0::: :::l 4 0 Q 3 2o
o
2 4 6 EXPOSURE, YEARS 8 10 1212 10 8 6 EXPOSURE, YEA RS 4 2 8 Horizontal NRP
•
NO. Verticalｾ
•
566•
•
c 659 .t.-.
0 788 x 842•
....J10
0
With NRP Without
9 Sealer NO. Sealer
785
•
•
786 ... 0 787 8 0 788 x 7 ｾ Z I - 6 co::: IX: >l -S ...J co co::: IX: ｾ 4 0 3 2 12 10 8 6 EXPOSURE, YEARS 4 2ol-
--.l..- ---l ..l.- ----L ----lL- ---'o
8I1U47-IO 2 1 8 6 4 EXPOSURE, YEARS 0 2 0 EFFECT OF SITE FIGURE 6-10 3 NRP HaIi fax Ottawa NO. 566
