plating, anodizing, & finishing Q&As since 1989
Restoration of corroded hot dip galvanized parts
August 11, 2010
I am attempting to inexpensively restore weathered galvanized mild steel housings that have deteriorated to the point that several areas are mildly corroded/rusted.
My first thought is to remove the rust and topcoat with zinc spray galvanizing (cold galvanize). The new coating must be heat resistant. (up 10 800 degrees F) and retain the original appearance.
1). Is this process viable?
2). If so, what would be the preferred rust removal method that would not affect the existing zinc coating? (Would electrolysis remove the zinc coating? If so before or after the rust?)
3). Would a prep coating be required to assure topcoat adhesion with this method?
Hobbyist - Milwaukee, Wisconsin, USA
August 14, 2010
Remove rust with ammonium citrate 5%,pH 3,5(1 lit water/50 gm citric acid/+add some ammonia -pH must be 3,5).Then you can pretreat cleaned surfaces with tannic acid based rust converter(20 gm tannic acid/15 gm phosphoric acid/1 lit water).After that you can use cold galvanize or zinc dust mixed with waterglass(thick paste).Hope it helps and good luck!Goran Budija
- Cerovski vrh Croatia