Document JYe50vqGjrGQ479p8VLMw5w6

. V.-: IS MIBSiLl UmUIHI L11I CC: Isdexed J* B. Bullitt, Wilm, B, Russell Morgan, .Lab; P, B. Evans9 Lab, S* C Homing, Lab, Ho Jo Stuart, Lab, ^iie? ib x o Marshall Laboratory October 6, 1952 MEMOEAMPUM REPORT MO. MLTO*g ' ' . ' * rcL' Cr,:iy .^4? METALLIC GOLD COATIBG OH PIGMENTS Since colloidal gold suspended in an aqueous solution is known to give a range of colors depending on particle sis, interest- tng optical effects might b obtained by depositing a fine layer of gold on pigments, . It was found that certain experimental conditions gave a purple deposit on -28 which approximated the tint used in refriger ator enamels, Thus the purpose was reduced to an attempt to doterrain the amount of gold required to obtain this commercial tint and to find the best conditions for reducing the gold. S2agih8s Two methods were tried of reducing a gold salt' CAUCI3HC13HgQ)2 (a) evaporation onto a pigment in a vacuum, and. CbJ reduction in an organic medium. The evaporation technique was discarded largely because no method was found of spraying the pigment through the gold vapor -at a slow enough rate to allow satisfactory deposition of the gold .on the pigment. If the gold chloride was mixed thoroughly into -28 and if this was then ground into RG-905 (.50/50 normal-isobutyl methacrylate solution!, a purple gold was deposited on the pigment which gave a reflectance curve almost identical with the tinting color used for refrigerator enamels* Various other solvents were used, such as acetone, diacetone alcohol, formaldehyde, etc., in place of RC-905. but only .diacetone alcohol gave a purple color;which was not' as intense as was that obtained using R6-90J. The purple coated pigment in RC-905 was added to an untinted refrigerator enamel until the proper reflectance curve was.obtained. The cost of the gold chloride needed per gallon of enamel t give this curve was fl.04, Xliis is much too expensive and cannot approach the present cost or tinting*. 4 N35456 v-fciSi* v*^;v -2~ The program was dropped because of the prohibitive cost of the gold color. SBf:hm 9/30/52 LABORATORY mMtLJi .-ffilLHOLLAM) k DUP030003427