INDUSTRIAL AND ENGINEERING
a46
CHEMISTRY
Vol. 25, No. 8
TABLEIV. EFFECTOF VARYINGPOWDERFINENESSAND CONTENTON MOISTURE IMPEDANCE OF ALUMINUM PAINT
nonvolatile matter. The paints made with aluminum paste pigments used 2 pounds of paste per gallon of vehicle. (One-coat films of aluminum paint made with varnish D) The Standard Varnish grade is the one most commonly used in aluminum paint; Standard Lining is a somewhat finer POWDER CONTENT PER LITER(GALLON) MOISTURE IMPEDANCE grade making a much smoother paint film, while Extra Fine OF VEHICLE Obsvd. Interpolated PIQMENT Lining powder is even finer (this grade is commonly used Gams (Pounds) in printing inks). The paste pigments 1 and 2 representing two different manufacturers' products are shown here because of the apparently growing interest in alun+um paste. The results reported have shown the relatively high Standard Lining powder 60 3.2 6.2 120 7.2 4.6 moisture-proofing efficiency of aluminum paint as initially 180 9.1 6.9 240 11.9 10.0 applied. However, of even greater importance is the ability 360 19.4 19.4 of a paint to maintain a high moisture-proofing efficiency Varnish D' alone, without powder 0 2.9 4.0 over a long period. Most of the coatings which have been Varnish D: 80-gal. varnish with 49 per cent nonvolatile content. investigated are now under exposure, and determinations have already been made (4,5 ) which indicate that aluminum OF ALUMINUM PAINTMADE TABLEV. MOISTUREIMPEDANCE paint does retain a high moisture-proofing efficiency. Other WITH VARIOUSGRADESOF POWDER IN VARNISH D results will be reported a t a later date. (80-gallon varnish with 49 per cent nonvolatile content) MOISTURE PIQMENT CONTENTIMPEDANCE InterCOATS % by wt. ?r?Obsvd. polated
PAINTCOATINQB Standard Varnish grade Standard Lining grade Extra Fine Lining grade Aluminum paste pigment 1 Aluminum paste pigment 2 Aluminum primer (Standard Varnish) 2 coats leadiinc in oil Aluminum primer (Standard Lining) 2 aoate leadzinc in oil Aluminum primer (paste) 2 coats lead-zinc in oil
+ +
+
1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
21.5 21.5 21.5 21.5 21.5 21.5 21.5 21.5 21.5 13 13 13 14 14 14 21 5 { Primer Topcoat 66:O
Primer {Topcoat Primer {Topcoat
8.7 8.7 8.7 8.7 8.7 8.7 8.7 8.7 8.7 4.9 4.9 4.9 5.3 5.3 5.3
8.5 18 28 10 19 26 9.6 19 26 5.0 9.3 14 4.4 9.5 13
8 7 2 4 : 4 ] l4
21 5 8 7 66:O 2 4 : 4 } 13 6 6 . 0 2:::) l2
9.2 22 34 12 25 36 13 27 36 7.8 17 24 7.9 18 25
9.7
'' ''.' 8.3
LITERATURE CITED (1) Browne, F. L., IND. ENG. CHBM..19, 982 (1927). ( 2 ) Dunlap, M. E., Ib
