Document Oz0nJgOKRK094pJz9OmkZXXrv
Al l ie d b s s e a ic h b u l is o t h o mier 10=53
SU!JEST PDBLIC1TT IMA = S-W #450 TMJMCQ&SM
Prepared "bys Dr. C. D. Holley T. M. lei son
August 15, 1939
AT.T.mm HSSEASCH LABORATORIES CHICAGO, HLIHOIS
N12514
. 'Tublicltv Data * S-W J45Q Undercoater
She thvm "Controlled penetration" used so extensively is describ ing the performance of paint undercoaters is a ^catch the eye" phrase meaning little or nothing.
Instead of how much oil shall be permitted to soak into the wood, it is rather a dual situation of how much oil in quantity shall -remain in the paint film, and how much, shall go into the wood surface*
In two paint undercoats, the some percentage of oil my penetrate into the wood, yet one paint will give excellent durability and the other fail badly, because in thb second case there was not sufficient oil present to provide for the proper quantity in the film end also in the wood#
In practical formulations of undercoaters, the pigments used control in a large measure the amount of the oil retained in the paint film. She outstanding success of tihite Lead as h highly durable paint pigment is due in an essential measure to its ability to retain the proper amount of oil in the film for maximum durability.
Most pignents vary materially in their ability to control the performance of the oil, some retaining on excessive amount in the paint film, some giving too much oil to the wood surface over which applied and the problem of a wise selection is important.
Oslo Leaded Zinc is the only other pigment we know of which has an oil holding quality closely similar to that of Hhite Lead. Ihese two pigments are the predominant constituents of S-W*s #450 Under coater end control the balance of oil in the film and in the wood.
0007-SWP-000006697
. In two undercoat paints containing tie same volumes of oil and. pigment, which in one case' was'Wilts Lead and in .the other Oslo Leaded Zinc, spread equally on a normal wood surface 22.5 gal. oil went into the wood and 24.8 gal. retained in the film of the WL Pi 21.0 u ! ' n if n 26.3 " * b u m n k Oslo
Leaded Zinc Pt. If the combination of pigments used do not have the proper oil holding qualities the formula becomes unbalanced and frequently an insufficient amount of oil will be retained in the film, tending to loner durability, peel ing, flaking, etc.
Aside from a pigment combination of proper oil holding qualities, there must be sufficient oil present to thoroughly saturate the wood fibres at and near the surface to prevent undue alternate swelling and shrinking of the wood surface during rainy and dry weather, thus producing a solid foundation for the paint undercoat; otherwise, poor durability con result with attendant peeling and flaking of the paint film.
The performance of two well known paint primers, designated as
Primers "A* and "B" compared with S-W's #450 Undercoater is shown by the
following figures, en the basis of 100 gallons of paint.
feint Primer "A* paint Primer MB'8
Total Oil Gals. 39.7
46.5
Oil Absorbed Gals. 22.2
28.6
Oil in film Gals. 17.5
17.9
Per Cent Oils and Figments in Film Oil Firoent 40# 60#
43 57
S-W #450 Undercoater 47.3
25.1
22.2
47
53
0007-SWP-000006698
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sparing Primer "A* with S-W's $+50 Undercoater, it appears to he deficient both in its capacity to supply sufficient oil to the wood surface aad also to retain sufficient oil in the paint film, to ensure high durability.
The comaor varieties t*f rood need in house construction vary mater-ially as to their porosity and in the amount of oil required to "satisfy* the wood surface. It is obvious that S-U '3450 Undercoater has a considerably greater margin of safety in doing this job adequately end giving excellent durability oyer a wide variety of wood surfaces.
Comparing Primer "B" with s-W?a #450 Undercoater, we note that while the total oil content is excellent, it appears unbalanced in its capac ity to retain oil in the paint film. A deficiency in this respect Can be serious as to durability as above indicated.
Heither paint Primer "A" or "B,: contains Ozlo Leaded Zinc, regard
ed as a most necessary type of pigment to give balanced performance of the oil
in both the film and on the wood surface. S-U #450 Undercoater does contain the
proper percentage which together with the high Shite Lead content serves to
maintain a balanced performance,
,^
It is to be noted that a lack of balance may not show a lowered durability until one or two years after application of the paint, when peeling or finking from the wood may occur, or peeling between coats due to a lade of "balance* between the Primer and the Finish Coat.
0007-SWP-000006699
Fatelarced Primer Itelilting ia Peeling from the Hood
0007-SWP-000006700
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Hir.K'
Tmm
Unbalanced Belation Between Primer and finish Coat Besalting in Peeling Between
Coats
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1 very important factor governing the durability of any paint
system is the total film thickness of that paint system as actually applied
on a given surface. Obviously, the actual flirt thickness of a given undercoat'
S3 applied depends principally on
(a) Yolune of pigaent plus inert
(b) Total volume of vehicle solids .
.
(c) Per Cent of oil absorbed and per cent retained in film
It is generally agreed that for an exterior paint system to have adequate protective value and to give satisfactory service that the total actual film thickness should not be less than 0.004*. Beferring to Table 1 attached, it is interesting to note that the larger amount of oil retained in the film by Bex 450 and the Ben Jersey Zinc type primer definitely contributes to greater film thickness and therefore better durability of the system.
The spreading rate obtained with any particular primer or under
coat er under practical painting conditions will vary according to its specific
characteristics. Assuming two spreading rates within a reasonable range, i.e...
400 and 500 square feet per gallon respectively, and allowing for absorption
of vehicle solids, we find that the actual film thickness contributed by the
. various first coats are as follows:
Irebs Broeker^s 1st Coat
400 so.ft./sal. 0.00144*
500 so .ft ."/gal. 0.00115"
SWP Outside White 1st Coat Beduction
0.00145*
O.OOII6"
W. L. in Oil 1st Coat
0.00122"
0.00098"
Bow Jersey Zinc Primer 450 tJnderooater Paint Primer "A" Paint Primer "1"
0.00199" 0.00192" 0.00167" 0.00173"
0.00159" 0.00154". 0.00134* 0.00139"
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Kte greater /lira thickness of #150 Undercoat as compared with
white lead: in oil, sad primers such, as "A"1 and
naturally makes a greater
contribution toward the final film thickness of '.he entire paint system applied*
Other things being equal, superior durability would result.
fable 1 Paint Primers Distribution of Oil Between Wood and Paint Film
Formula
Total Oil
Gals. Gals.
Yol.of
Per 100 Gals. in Pig P.Y.C* P.V.C., $ Oil. Film
Gals. Abs. Film ment Paint Film Abs. Gals.
Krebs' ,1st . Coat
6S.3
50.5 17.8 18.1 21.0$ 50.5$ 74.0$ :35.9
SWP Outside White 1st Coat Beduction
66.6
49.5 17,1 19.1 22.3 53.0 74.4 36.2
White' Lead in Oil , '1st Coat
58.5
45r7 12.8 17.9 23.0 58.0 78.0 30.4
lew Jersey Zinc Primer
58.9
35.0 23-9 25.6 30.2 5I.7 59-5 49.5
450 Undercoater
47.3
25.1 22.2 25.7 35.2 53-7 53*0 47.9
Paint Primer BW
46.5
28,6 17.9 23.9 33.9 57.2 61.5 41.8
Paint Primer 11A"
39.7 . 22.2 17.5 25.8 39-6 59-5 55.8 43.3
Tablo 2 Effect of Individual Pienents in 4*50 Undercoator Tsroe of Formulation
Pigment Titanox 1
Total Oil Per 100 Gals.
47.3
Gals. Abs.
26.7
Gals, Gals. in ' PiC-
Film nent
20.6 25.7
P.T-Ce Paint
35.2$
p .y . e. Film
55.6$
$ Oil Abs.
56.5$
White Lead
47.3
22.5 24.8 25.7 35.2 50.8 47.5
leaded Zinc 35/^5
47-3
21.0 26.3 25-7 35.2 49.5 44.4
Asbestine
47-3
13.72 33.58 25.7 35.2 43.0 29.0
Asbestine
75$
Jmorphous Silica 25$
47.3
14.75 32.55 25.7 35.2 43.3 31.2
in Typhous Silica (calc.) 47.3
17.9 29.4 25.7 35-2 46.6 37-8
Titanium Oxide
47.3
5.91 41.39 25.7. 35.2 38.8 12.5
0007-SWP-000006704
Betfclp 5 Sffflet.'&f Otis, to'4*50 Undercoator OygM of Pigmentation ;
Vehicle
Qonbined Vehicle Eos 450
(2)
(7S5)* (2) 45$ (2281) 55$ (2281) (Sale. 5
(2)
(785)
Total Oil
Guile uviis-
Per 100 Gals. in ?ig- p.v.c. P.V.C. $ Oil
Sals. Abu. Film ncnc Paint Fiin Abs.
47.3
25.1
47.3
27.4
47.3. . . 26.5
22.2 19.9 20.8
25.7 25.7
25r7
35-2$ 35.2 35.2
53.7$
56.3 55.2
53$ 58$
56$
47.3 47.3 50.3 5O.3
23.2 19.9 29.8 ' 29.7
24.1 27.4 20.5 20.6
25.7 35-2 51.6 25.7 35.2 48.3 25.7 33.8 55.5 25.7 33.8.0 55.5
49$ 42$ 59.2$' 59.0$
e Slightly heat bodied Linseed Oil e Strongly bodied Tang and Perilla Oil
Table 4 Absorption of Oil Prop Finish Coat bg Prtolne' Coats
Ten'Coat
STO - Oat side
White .
. les 471
Total Gale. Oil/100 Gals.
. . 66 -5
Gals. Abe.
4.25
Gals. Left
61.25
$ Abe.
6.4$
rig.
P.V.C.
28.4$
P.V.C. Tila . .
29.7$
450 Undercoat Bs 471
66.5
3.86 62.& '5.8 28.4 29.6
Paint Priaer "A" Bos kjl
66.5 ' 4.25 61.25 6.4 28.4 29.7
sm ,& OTsMLS
0007-SWP-000006705