When you say contamination of the scrap is there someway of
decontaminating the scrap before heating or would the
contamination be integral to the material.
The simple answer is not to contaminate in the first place. If you
want to reuse your own scrap here are some basic rules:
Clean your bench first thing in the morning, and every time you
There should be no food, coffee, and etc., on your bench. Maintain
clean hands throughout the day.
Throw away all fancy abrasive wheels. When wheel is used up, most of
it winds up in you fillings, and it is impossible to predict what
effect it would have on your metal.
Learn to do you work with files, scrapers, gravers, burnishers.
Rubber wheels, preferably pumice, should be your last resort and
very limited one.
Provided all of the above is followed:
Separate fillings from scrap pieces.
Boil out pieces in strong detergent, calcium carbonate is the best.
Using iron pan burn out organics from fillings.
When cool, spread on piece of cardboard and work over with strong
magnet to remove everything magnetic.
Mix fillings with fair amount of smelting flux.
Many recipes exists. Try one part of borax, one part of boric acid,
and one part of powdered charcoal. There are recipes of limestone,
ground glass, and etc. The simpler, the better. Do not complicate the
recipe unless you have a reason for doing so.
Wrap the mixture of fillings and flux in paper napkin making a neat
package. Slowly pour water on your package until it stop absorbing
it, and let it alone overnight. Water will dissolve borax and will
form binding to hold fillings together while melting.
Melt your fillings package separately and cast it in water. It is
more difficult to melt fillings than pieces. You would need to use
neutral flame. That is the reason for using a lot of flux to protect
the metal. After casting, collect all the pieces and melt it together
with other scrap pieces. Use only a little flux and reducing flame.
It may sounds like a lot of trouble, but it isn’t. It quickly
becomes a second nature. Besides, once the discipline is imposed, the
quality of you work will improve by itself.