[TheForge] Phosphoric Acid

[Cindy and James]

All this about phosphoric acid, I have a question.

Have any of you used it and then painted over it?  Exactly what was the 
procedure and what was the long term result?

I have some 200' of 8" and 12" I beams in my shop supported by 15' long 
5.5" pipe columns,  and all were significantly rusted when delivered 
from the steel yard.  After installation, I wanted to paint and looked 
for something to get rid of the rust, etc., and came up with phos acid.  
Bought at local TSC store.  I painted it on w/ a 4 " brush and waited a 
couple of days.  It turned black if I recall correctly.  Then I painted 
with a coating of high gloss black equipment enamel.  That was about 4 
years or more ago and it still looks great.  It is inside.

Recently I built a balcony railing for a client and recalling my 
experience with the I beams, etc., thought I would try that.  Well, that 
was less than a year ago and the paint has started chipping off and rust 
bleeding through on some parts of the railing, scrolls, bars, etc.  
Also, a very obnoxious white powdery substance is leeching out from 
under/through the paint and running down.  You can wipe it off with your 
finger.  I went back the last 2 days and wire brushed, scotch-bright, 
sandpapered the thing, and repainted with flat black rustoleoum.  Took 
me 8 hours, 1/2 of which was hanging on a ladder 30 ft up on the side of 
the house!

If I had had an inkling this would happen, I would have had it powder 
coated or at the very least, hired a good painter.  And that is what I 
will do if my repaint job fails (hire the best painter in the area).

This is my deal and I feel responsible.  If it were 5 years, that would 
be something else, but not 7 months!  I did all the ironwork in this 
client's new $1.5+ home and everything else is great but this.

Any ideas welcome.


James Allcorn
Bois D'Arc Forge Blacksmith Shop
Paris, TX