Document 2jN8Dw7zv0128aQ91Q2ey0N3p

I ALLIED RESEARCH BULLETIN NUMBER RC-57 SUBJECT: ACICULAR BASIC LEAD SULPFATE - BEHAVIOR IN 77HITE PAINTS C. H. Adams May 22, 1940 ALLIED RESEARCH LABORATORIES CHICAGO, ILLINOIS 0007-SWP-000006707 'Acicular Basic Lead Sulphate Behavior in White Paints ~ ' general Statement ^ Same years ago the National Lead Company developed an acicular type of Basic Lead Sulphate v according to report by a precipitation process. Claims having been made for increased durability of those types of sino oxide 1% which had an acicular structure, the National Lead technicians were inclined to claim superior durability for their new product as compared with the standard type of Basic Lead Sulphate, on the same basis of reasoning, i.e., that a long needle shaped crystal afforded greater durability than the ad mixture of very short rods and rounded particles of co-fumed Leaded Zinc* Test Procedure An exposure sorios was begun in 1938. Three coats self-primed on White Pino* vortical southern exposure - Chicago paint farm* Tho stand ard formula of SWP White was used as tho base formula and as the guide coat on each panol* The pignent composition was represented by: 46$ Leadod Zinc 412 dry or substitutod pignent. 34$ Quiok Process Lead (S-W Carter type) 1C$ Titanium Oxido 1(#S Asbestine. The pigmonts on idiioh this exposuro sorios were basod are: 1* Oslo 412 Block B production. 2. Oslo 412 Block D production. 3. Moohanical mix 35$ Standard B. Ld. Sulph. 65$ Now Jorsoy XX Zinc Oxido. 0007-SWP-000006708 -2 .4* Mochanical mix 35# Acicuiar B. Ld. Sulph. 65?$ Now Jersey- XJC Zino Oxide. 6, Mechanical Mix 35# Standard B* L. S. 65# American Zinc Acicuiar Zinc Oxide. 6, Mechanical mix 35# Acicuiar B. L. S. 65# American Zinc Acicuiar Zinc Oxide. This exposure series brackets Ozlo 412 against mechanical mix tures on ono hand and against tho effectiveness of acicuiar Basic Load Sulphate soparatoly or in conjunction with acicuiar zinc oxide on tho other hand. -Exposure Rosults Aftor 21 months* exposure sufficient film breakdowns havo occurred' to indicate definitely tho durability characteristics of Acioular Basic Load Sulphate. 1. Tho 6o-fumod 412 Loaded Zinc oxposurcs show no signs of failure. 2. The oquivalont mix of sto.ndard grados of Basic Load Sulphate and American Process Non-Acicular Zinc Oxide is badly chocked and cracked, confirming previous similar exposuros. 3. The oquivalont mixturo of Acicuiar Basic Load Sulphate and standard Non-Acicular Zino Oxide badly checked and cracked. 4. Tho equivalent mixture of standard Basic Load Sulphato and Acicuiar Zinc Oxide show no signs of failuro. 5. Tho oquivalont mixturo of both Acicuiar Basic Load Sulphato and Acicuiar Zinc Oxide show slight but dofinito chocking. In tho above exposures tho Basic Load Sulphato roprosents 16# of tho total pigmontation and the Zino Oxide 30#. 0007-SWP-000006709 -3- Even in the small percentage presont, the Acicular Basic Load Sulphate* has shown a distinctly dotrimontal offoct. Tho prosenco of the Acicular Zinc Oxido with standard Basic Lead Sulphate shows improvod durability over ordinary Zinc Oxide and to dato equal to co-fumed Loaded Zinc Oslo 412* Tho situation can bo sunmarizod as follows: Wheroae former mochanical mixtures of Basic Lead Sulphato and Zinc Oxido have shown marked inferiority as to durability compared with cofumod Loadod Zinc, mochanical mixturos in which Acicular Zinc Oxido is usod /is*.' 7*8.7 show a markod improvomont in durability* Aciculcx Load, unlike Acicular #5 Zinc, is a detrimont* CHA:MF 3&X - 0007-SWP-000006710