Document Gzo06KO78LK2e62xxrr6xkMYv

^2*53 Cross deference; Extenders Mica House Paint 00; Mr, C* lU E*- Merisi* Lab* Dr Paul Robinson, Lab* Mr, ff. 7/, niff, Lab, .Mr, .Stuart Grates, Lab* Mr* &* 0. fitKgsraldj, Lab* Mr. 'John i.arshall, Es? rat mi last 5^ 5w c. i Philadelphia Labors yfll a October 5, 1949 inm 10 MARSHALL liiaiORAKXfUH REPORT HO, M-316 muss s bq bh p igc* vt pangs mw . IMs is to record the initial properties of house paint made with a sample of 325 mesh whits water ground mica obtained from the English Mica Company, Stamford, Conn, The code of the sample is 0318928* The advantage claimed for mica in house paint is "greater resistance to cracking and longer life* The paints described in this report have been placed on exposure "in Series ^9998. Mo action is contemplated until result's are obtained from the exposure tests, l Camples of mios from two other suppliers have been exposed previously in house paint; (l) Mineral!te, a dry Ground grads; (2) Aratone, a wet ground grads. Thev are a little more durable than magnesium silicate* The flakes are so large that they make the film glitter after it has weathered; they have not been used in house paint white 6r tints'for-<thia reason, SUMietryi According to the recommendations of the supplier., mica has been used at .10# by weight of the tots! pigment in three compositions; (!) 301-867 Lead-free Atlanta White (2) 301-868 Lsad-frae Cream Ileus Taint (3) 374-817 House Primer la the Primer the mica has also been tested as the entire extender portion. s In general, xnioa lower 3 the soli la content and the gloss cf the paints, increases the "slip" of the paint under the brush and has somewhat poorer color than cur present extenders. The improvement in durability would have to be large to offset the disadvantage of low gloss* Solids Content; In the V/hite and Cream topcoats 10$ of mice lowers the volume solids about 5$. This la not necessarily a disadvantage if the durability is satisfactory at the lower solids content. In the 1 rimer, 10$ of mica has no effect on solids content. This product is already heavily bodied by aluminum stearate, so that the additional bodying action of a small amount of mica is negligible* However, when mica is used as the sole extender, the solids by volume are lowered from 60 to 50$. Gloss! In the <?Iiito and Cream topcoats, the gloss is lowered from high to medium. This results in slight flashing. Since we have put much effort into the elimination of flashing in our .house paint, the effect of mica would be a serious draw-back to its use, Since the primer is flat, mica has no effect.on its appearance. The uniformity and hold-out of the primer' are equally good with and without mica. Hone of the topcoats or primer showed a micaceous glitter, in the fresh film. However, this appearance may de velop on weathering, and the exposure, series will be reviewed critically for appearance. Color: In the white, the color with 10$ mica is very slight ly worse than the control. The difference is not large enough to rule out consideration of this pigment. In the primer, the color with 10$ mica is perceptibly grayer, and the color where mica is used as the sole extender is very poor. However, since the color of the primer is less im portant. than that of the topcoat, small amounts of mica could undoubtedly be tolerated. Brushing; In this particular test, 10$ of mica improved the 'brushing of the white topcoat. The white control showed a definite drag, and the increased ''slip55 of the paint containing mica constituted, a definite advantage. However, the control was not charactoristi.c of the brushing of 301-66? "it is probable that .10$ of mica would be acceptable for brushing but would not ordinarily .produce a worthwhile advantage. DUP030003095 3 x< . la tHe primer* 10> of mica has ao effect on the brush ing Vihsa mica is the sole extender* the product has excessive slip and the brushing is unsatisfactory, Notebook Reference: Notebook 5075, pages ,58-74. XIFS :hfm PHILAhiSU'HIJi LABOkA'fOf'Y WILLxm P, 3IWGL3T0N DUP030003096