I wrote to the Picklex people and posed the issue about cast iron and Picklex 20. I am not sure it adds anything to what has been given before and I probably could have asked it more clearly to get a better response. But, here is what I asked (with their response following):"I have a tractor in the restoration process. I am strongly considering using Picklex 20 to treat the rusty cast iron under the paint (after chemical and mechanical wire brush paint removal). A restorer has said that acid (picklex) on cast iron is not a good idea (apparently some concern about remaining acid in the "pores" that could later affect the paint). What is your response? Will it work? And can I prime (epoxy primer) directly on the dried treated area or must I remove some of the black "phosphate?" residue. Thank you... Jim"
Their response was:
"... I don't think there will be any problem. Picklex 20 has been in use by lot of companies for last 7 to 8 years with no problem (when used properly). For rusted surface, make sure to remove all loose rust up to the metal surface. Then apply Picklex 20 which will convert the rust 100% to a protective coating. Wipe off all excess chemical from the surface after a minute or so. The coating should be thinnest possible coating. That will provide a good bonding with the primer. Use epoxy primer. Make sure you do not use any self etching primer. If you like to test, perform the above procedure up to priming, on a very small area (about 6" x 6" area). Then after curing of the primer, perform a bonding test (cross hatch test by scribing thru the primer down to the metal, few 1/4" parallel lines. Then scribe 1/4" perpendicular lines over the previous lines. Then stick a tacky tape on the cross hatch and pill [sic] slowly upward. If the paint did not bond, it will come off). If the bonding comes out good, use the same way for all the area you want to do. Best regards, ..." He probably means "through priming" not "to priming"... JIm
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