Document 71D2Ykw5zy2mpeQKomXXvRRQe
Mg^caAKllbSf 55P0RT SP3CIAL HOUSS PA KIT PRIMSR STUDIES
General Statements In continuation of our studies on the two coat house paint system,
it becomes quite evident that the advocates of this syten have overlooked the dur ability of the primer itself when exposed to climatic influences.
After two years of average exposure on new wood, the top coat of
a two coat system has usually eroded away and th
protection afforded the
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wood depends upon the priming coat. On repaia^^johs^idiere a primer is employed
... ' .5-^#^;-.- ~ ' . to "uniform" the surface, the. durability of.jthegpriier?is again of considerable
importance for the same reason.
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Practically all of the special house paint pricers'contain a con-
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siderable percentage of bodied oil for controlled penetration, whereas with a
regular mixed paint which is'reduced for priming, ,,a,,,liberalpercentage of raw :
linseed oil is added. This abundance of raw oil is available for penetration
as the character of the wood will permit.
The question arises, docs the use of a special primer of slight penetration protect the wood as well as the conventional first coat reduction, using only raw oil? The principal claims made are their superior performance on woods which ere difficult to paint satisfactorily from the standpoint of dur ability. Coniferous woods, such as Southern Yellow Pine, Douglas Pir and Calif ornia Pine would fall in this classification.
It was therefore considered desirable to determine how typical primers would wear on flat grain Southern Yellow Pine, as this is a type of wood which has a tendency to crack when exposed to the weather. A comparison was mad*:
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feetBeen the primers of controlled penetration and the conventional first coat re daction of a mixed paint using raw oil.
Aralfeation;
This series comprised 9 members, of ahich p were experimental and
4 representing competitive house paint primers (Devoe's, lallhide. Titanium Fig
ments Recommendation RTr-401, and Mocmhite (Benjamin Moore). The primers were
applied as one coat work on flat grain Southern Yellow Pine six inch clapboard
siding. The SIP Site (Titanium Dioxide Type) was used as a guide on each panel
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and reduced according to the label directions. The panels uere exposed vertical
south on June 2, 1937 for a 'period of 20 seeks at the Sheruin-Iillisas Exposure
Farm, at Chicago.
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- COMPOSITION 0? ISnSES-
COMPETITIVE
Dsvoe*s Undercoater
Site
- Sine
-- ; Lead Zinc
Lead Titanox Sal- Titanium Sal- Qx-
Carb.
B. ulhide Dioxide abate ide
Mag.
Sil- Del
icate ite
3Sfg
37^
2556
Tallhide Ex. Primer
7$ 27% 5056 1^
T.P. Cos. MI-401
Reacmnendat ion
3356
37<
25*
Moorwhite Ex. Primer
Eo Analysis Given
Mica
iNCT ir-ir? z o n a l Dsmcpan^'s
Acme Balanced Ex. Primer
Site
Zinc
Lead
Msg.
Lead Titanox ful- Titanium 3ul- Zinc Sili- Cel-
Garb-
R. abide Dicxir.e -shat** raids cute ife Mijr.
gl'
3%
3* 7%
Lowe. Bros.Ex.pri;r. fO%
10% 30%
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shite
Zinc
Lead
Mag.
Lead Titcnox ,, Sul- Titanium ..Sul-. : Zinc Sili- Cel-
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Garb.
5. nhlde Dioxide nhate ' Oxide ' cate ite Mica
Special Primer for Y. Pine
78$ `
9$
9$
4 Sherwin-aTilliams
Experimental #1
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10$
I Sherwin-7illiems Experimental #2 81&
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SWF White (Sex 471)34|;1
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Exposure Results:
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These exposures have passed through a complete summer and are now approaching the critical jart of the exposure cycle. The priMng, coats have weathered sufficiently so that the following comments can he cade. The protective value or integrity of the primer is rtted in direct comparison to the guide that was painted on each panel. STTP Whits was used as a guide and reduced according to label directions for priming. -
The failure as to checking and cracking appears to be the least on the Acne experimental and the special development for yellow pine, but from the standpoint of the guide, the Acne primer is definitely better. The Devoe and 115-401 both show a slight improvement over the guide in this respect. The special primer for yellow pine, Wallhide and the two Sherwin-Williams experiaentals show \ the same degree of cracking as their guides. The Lowe Bros, development and Moorwhite primers are cracking more than the guide and are the poorest primers of this set.
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1 decided difference Sa chalking i noticed between ties .irafiong primers. Eie Sallhide cad Moorwhite primers ere cholkisg eii^iiy and are very
similer to the1 guide. The Devoe, Acne* U7-4Q1, and Shenrin~7illieas Special Be-
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velojlafent 'giye-ell shoeing modterate chalking characteristics* She Lrve grcc. r
Begular Sherwin-yillioas Sxperinental, ad the primer for yellow pljt ere sLnil:ing. with .tepid erosion. `
The opacity of all the primers is definitely better then the guide
(SEP Shite priding coat), with the except ion of Znllhide end ecrwhivfc lu.->
fellhide priaer is slightly better than the guide endHoorrfhite is no*
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opacity*
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,froa our observations of these exposures,;: it ioppeara inu'i \hc.->
s>ac improvement in durability obtained by the use of the : ' c
> the eonventtonal first coat reduction for priming of ner '-ooc. Te
primer's : o inL*s..u..l.t.&. btslued on exterior primers indicateifthat c idefibii e 'rororcT
exposure *..................
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feeade bef*ore a t*w--o c--oa*t system wwHill^l bbeeodbhtai ined!which npprcuchss
will .hove , the .^tiefB^^*f*OcBoe of e
coat system self-priced.
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