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Loss of grain

We currently electrochemical grain aluminum. In normal cases the grain is very white and even. We are experiencing problems with losing grain starting from the center and moving toward the edges. All baths are in specification and we have tested for copper in the aluminum web. We use 1052 alloy.

Jim Terry
lithographic plates - Jacksonville, Texas, United States
2004

You gave us very little information about your processing and chemistry. When you say "losing grain" do you mean little or no attack or is it some masking pattern that is lifting up?

Guillermo Marrufo
Monterrey, NL, Mexico
2004

We use caustic for degrease and nitric to grain (we replenish both). It looks like masking. Something either insulating the metal or we could be possibly burning the metal, but it always starts in the middle and works to the edges. We have checked our solutions for impurities and our aluminum before and after(during loss of grain) for differences and have found nothing. This does not happen all of the time and we have found no correlation to any metal suppliers or chemical suppliers.

Jim Terry
lithographic plates - Jacksonville, texas U.S.
2004

Let me tell you that nitric seems strange to me for aluminum engraving. Also caustic for degreasing it. You say you suspect the metal is getting burnt. Are you applying electric current and how much (Amps/sq. in)? How's your acid concentration in the nitric? Could it be a problem with temperatures?

Guillermo Marrufo
Monterrey, NL, Mexico
2004