Document bB3G0n6RXMdGJRVbQKY36KGBk

j#S Cross Index; - OCs Sis?, ar, B. Bullitt, Lab. Me, J. W. Illff, tab . 301 Line Mr. C,, R. Bo Merkle, Lab. Sore on Staining of Hons Paints Me. Stuart Graves, Lab. trade Sales - General Mr. W. F, Singleton, Lab. "INDEXED'' I cm W lv Tt O P19.Q ** | @| cftcaiiyicji ' . fewgawgaj!fcjhg BETURN TB MARSHALL LABBRAIOBY LIBRARY INSPECTION OB SCREEN STAIN SERIES AT TEST BENCE OF THE NATIONAL PAINT. VAS!Mm AND LACftBER ASSN,. INC. On July 6th Mr. Stuart Graves and the writer visited the offices of Mr, John C, Moore, Director of the Solentiflo section of the National Paint, Tarnish, and Laoquer Asn, Ino. The primary purpose of the trip was to discuss and inspect a screen staining series which had been exposed by Mr, W. Lawall at the associations test fence in Lanham, Maryland. Discussions After briefly discussing house paints in general with Mr, Moore we were conducted on a tour of their exposure fences by Mr. Lawallp The scope of the associations work on screen staining is condensed in a single series of 52 panels whloh can be broken down as followsj 1. A screen enamel test over bronze and galvanized iron screen using on the frames a lithopone paint, a white commercial wnonstalaiag" paint of unrevealed com position,, and a titanium dioxide/lead/zinc linseed oil paint. a. The enamels used Included a maleic modified linseed oil resin, a black air-dry alkyd resin, a black oven-baked alkyd resin, a clear phenolio resin, and a clear spar varnish. 2. a test of uncoated soraens composed of various materials inoluding bronze, lead-coated iron, monel, plastic wLuraiteM, alclad, and stainless steel. The frames were painted with the same three paints mentioned above plus a white lead-in-oil paint. The screens were taoked to frames 2 x 1-1/2 x 1". A 6" ifide board was mounted directly beneath the screens to simulate the window sill or clapboards of a house. All exposures were north vertical only and the length of exposure in most oases was two years. *> 2 : Results & Conclusions: Detailed results are given in the attaohed set of tables. Unfortunately, there were several disappointing factors noted on this inspection Among these was the fact that the data for all panels was given only at nine months, and two years, Since most of the panels had started to chalk at 9 months, the significant period of staining between 1 and 9 months was evidently not covered. Also the composition of the paints and enamels were, in general, not revealed so that it was difficult to make any comparison be tween degree of screen stain versus composition of pigment and vehicle. Results were confused in several plaoes by the use of poorly protected iron nails and by drip from stained panels above. And, finally, it was agreed upon by Mr. Graves and myself that the conditions favoring screen staining in this particular looality was not as severe as is usually encountered. There is the added factor that only new screens were used and the position of exposure was north vertical only. In general, as far as the screen enamel series was con cerned, only one enamel did the Job - namely, the black alkyd resin applied to the screen by spray and baked at 250 degrees for one hour. All the other enamels failed between 9 months and 2 years. As far as the different types of metals are concerned, lead ooated iron and monel metal stained in several oases whereas plastic ''Lumite", alolad, and stainless steal were relatively free from staining over all paints tested. The house paint which Mr, Lawall claimed to be free from staining throughout the two year exposure was chalking very heavily compared with the other titanium linseed oil paint. We are of the opinion that this is an alkyd vehicle heavily loaded with free chalking titanium dioxide since several of the panels were already flaking and errodlug at two years north exposure. The white lead paints were relatively free from staining but this is not surprising since the panels were out only 1-1/2 years using new metal screens. Our own exposure results show that white lead in oil is usually slower to stain than a titanium-linseed oil paint but passes it in the degree of staining somewhere after 18 months. During the latter part of the day we were given an inter esting resume of work done on a method for testing fire retardant paints by Dr. Westlake, The work will probably be published in the near future, PHILADELPHIA LABORATORY HMKspp Att, R, M, KIRKPATRICK DUP030003137 REPORT HQ* M-259 DUP030003138