grumpy wrote:Thanks guy's, no sand blasting or steel wool needed. Thanks to advice from one of our friends here on the board I learned about Muriatic Acid. I use a 50/50 mix of acid and water, I put the parts in a tub and watch them boil, that's right boil. the acid eats away at the Iron oxide and whats left is the original casting. It is a bit nasty to work with and much caution should be used. It gives off gas, and a mist. Like death chamber gas. And if it gets in your eyes it can cause blindness. I wear my gas mask I had from my trip to Kuwait during the second gulf war. I found safety glasses were not enough. That gas is like a thick fog and if the wind blows the wrong way your at risk.
However it works great and does not scratch the parts. When there done put them in water and baking soda to neutralize the acid then rinse and dry. I use a blow dryer to dry fast before rust sets in,and it can very fast. You can get it at home depot for seven bucks a gallon.
I had heard of lye dips before but not the acid although it makes perfect sense. As a kid I worked in my Uncle's plating shop and we used "bright dip" before plating. That was also an acid bath and would heat it with a live steam hose! Talk about crazy! I remember the scrambling every time the OSHA guy came round. It would turn copper instantly bright!