I'm a commercial painter and the building I'm working has several hollow metal door jambs that have some really, REALLY tough stains on them. It definitely looks like some type of liquid caused them by the pattern of the stains; splattering and runs.
There was/is no residue from the liquid, however I tried wiping the areas down with several cleaners and plain water; vinegar, ammonia, dish soap, baking soda, simple green, etc. I haven't tried any heavy duty chemicals however I did use my normal routine of ; mineral spirits, denatured alcohol, acetone, laquer thinner, toluene/xylene etc. I've also sanded into the metal a bit so as to remove a thin layer but not so much as to have to use bondo to repair a low spot.
I've hit the areas several times with shellac, oil based primers, and even epoxy and they keep coming through everything I've thrown at them.
I have encountered some tough stains in my 25 years as a painter and have never had this problem.
One or possibly more of the aforementioned methods has always taken care of anything I've had to deal with.
I've asked several paint store reps and have asked around the construction community as well as other fellow painters and am coming up with nothing more.
In researching, the only thing I can really figure it to be would be a deep etching of some sort, I guess meaning that some type of acid got spilled and splashed around somewhere along the line before I got to them. I talked to all the superintendents on this job site and nobody has any idea of how it could have happened here so I'm left to assume that it happened somewhere between the factory and here.
I don't know a whole lot about steel door jamb manufacturing so I wouldn't really be able to tell what types of acids might be splashing around at them nor where they might be kept along the way from there to here.
If anyone has any insight into what I might be able to do to eliminate these stains, I would greatly appreciate it.
This hospital is getting ready to open for business and all the contractors can come up with for a solution is to replace the jambs. There's probably between 15 and 20 of them and I'd rather not have to come back here to repaint them all while this is a fully functioning medical facility. Anybody who works on these buildings will understand why! Thanks in advance for any info.