Letter 5041.

Precleaning of cold rolled steel problems. 

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I am gold plating some cold rolled steel that has an oily film on it. After I electroclean in a hot alkaline solution for several minutes the oily film is gone and the parts look great. When I soak them in the acid activator ( non electrolytic) for a minute or so, a greasy residue builds up on the edges of the parts. The residue is only on the edges. I have to scrub the residue off them with a brush. Is this actually grease or is something else happening? Any suggestions from someone familiar with this problem would be appreciated. Do I need a better degreaser? The electrocleaner seems to get them clean.

Terry Collins
- Cleveland OH

There is nothing wrong with brushing the parts if the production volume is low--it can eliminate the need for more noxious chemicals.

But if you need to do it chemically, the first thing I'd try is a double cleaning cycle: clean, acid dip, clean again lightly to remove the smut, acid dip very lightly--just enough to remove the alkaline film.

This may not remove a carbon smut; if it doesn't, then a strong dichromate dip may.

Ted Mooney, P.E.  finishing.com Brick, NJ

WE MANUFACTURE THREE ACID CLEANERS, WHICH HAVE THE PROPERTIES OF REMOVING (1) THIN WET FILMS OF OIL, GREASE AND RUST FROM THE STEEL SURFACE. WHERE THE OIL FILM IS ONLY THIN, AND WET, ONE OF THESE CHEMICALS WILL DO FOR YOU.

S. M. SUBRAMANIAM Guardian Anti-Corrosives Private Ltd. CHENNAI, TAMIL NADU, INDIA

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