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topic 0380

Pickling Paste for stainless steel

A discussion started in 1996 and continuing through 2003.
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What is the fastest way to get rid of the discoloration that occur from the welding of stainless steel.



I use a 70/30 mixture of concentrated nitric/fluorhidric acids for a few minutes.

Miguel Flesia
- Argentina


Beside the corrosive nature of the acid, the use of hydrofluoric acid in a hand operation to clean weld oxide is extremely hazardous as it is insidiously absorbed through the lungs and skin, causing permanent damage and death to internal organs.

pooky tom pullizi signature
Tom Pullizzi
Falls Township, Pennsylvania


From a poor mans standpoint, 50/50 hydrochloric acid is probably the quickest semi safe way to fix the problem. rinse well with warm water or it will rust later and or stain. Rubber protective gloves [linked by editor to product info at Amazon] swab and rub.

Fluoride is not that unsafe when you use ammonium bifluoride to get the fluoride content. By then it is so dilute that it is no more dangerous than the nitric acid is. 70% hydrofluoric is extremely dangerous until diluted and absolutely should not be used without extreme caution and by QUALIFIED TRAINED people only.

Polishing with a 410 SS wire rotary brush is a guaranteed way to have the area rust when exposed to high humidity.

James Watts
- Navarre, Florida


The best known way to remove heat generated discoloration off of stainless steel (any welded, laser or plasma or other heat generated method that causes it) is to use an electronic weld cleaner. Good luck and steer clear of those pastes, they are very very hazardous.

Glenn Mahon
stainless steel fabricator - Los Angeles, California

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