Putting the Shine Back on the Gloss Problem

Article From: Products Finishing, ,

Posted on: 4/1/2002

Question: This may be of interest regarding (NH4)2CO3, which is ammonium carbonate.

Question:

This may be of interest regarding (NH4)2CO3, which is ammonium carbonate. When trichlor or perchlor or any other halogenated solvent gets into a direct-fired oven, the solvent breaks down in the flame to produce hydrogen chloride, also known as hydrochloric acid. This acid can greatly affect gloss and even the texture of wet paints. To destroy acidic residues in a fouled oven, ammonium carbonate is placed inside on shallow pans. Contrary to Random House, it is NOT a mixture but a single compound. Ammonium carbonate breaks down thermally to produce water, carbon dioxide and ammonia gas. The ammonia is basic and therefore will neutralize any acid materials that may be present and corrects the gloss variation problem. N.R.

Answer:

Thank you, N.R., for putting the shine back on the gloss problem. You have cleared up the mystery about how to use ammonium carbonate to neutralize acidly fouled ovens. This is a further addition to the store of knowledge about paint and painting for my readers and me.

As for the background of this question, T.B. wrote in the October 2001 clinic that he had a fluctuating gloss problem. He thought it was related to varying the amount of catalyst used in two-component paints. He essentially wanted a table showing ounces of catalyst vs. gloss. I told him not to change the mixing ratio for the well-known reasons. Instead, I listed common causes of gloss variations in cured paint films.

In the December 2001 clinic, S.B. wrote helpful comments about how he solved gloss problems in ovens fouled by halogenated solvents. He used ammonium carbonate. I wasn’t sure how the ammonium carbonate was used and said so. N.R. came to my rescue and that brings us up-to-date with this column. Thanks again N.R. When I need a consultant again, I’ll know who to call.

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