Zinc Zinc

[shotman]

Well guys have found a sure way to find your zinc and to check and see if your alloy has zinc in it.
When you order your next Kroil get a pint of their EXRUST its good for many uses on molds too will take the rust out of the cavs. They have a special on the silikroil 2 for one. works as good as reg but takes longer to season the mold
Anyway if you put a drop on a wheel weight that you are not sure of I will foam
Kroil number is 1 866 598 1202

[lwknight]

Who can you order Kriol from?
My local auto supplies don't carry it anymore.

[The Double D]

what will foam, lead or zinc?

[Wayne Smith]

what will foam, lead or zinc?

Exactly. The original post is very unclear.

[mikeystew]

the acid reacts with the zinc causing a vigorous fizzling action. however...

i did a bit of testing today with muriatic acid, the veritable litmus test for zinc because i feared i may have melted a zinc WW and i got some interesting results.

i first tested the ingot i thought might be contaminated by placing a drop of pure acid on it. after about one minuite it started to bubble very faintly and darken the ingot under the puddle. i feared the worst.

next i tested an ingot made from very well sorted WW's melted in a small batch that i knew wasn't contaminated with Zn. same results, slight bubbling after a minuite or so and darkening. interesting...

i then tested a clip on lead WW and a zinc WW. the lead one had the same results as above with slight bubbling and darkening. the Zn weight on the other hand began to fizz intensely and and turned the pool of acid a snot green color.

until i can test a truely contaminated ingot im not convinced as to what the results would be, but i know that for me at least the acid gave me the impression of a false positive when i tested the suspected ingot. i believe the acid may have been reacting to other impurities in the alloy, but im now very curious to compare these results to the reaction i would get from an ingot tainted with 3-5% ZN.???

[sagacious]

i believe the acid may have been reacting to other impurities in the alloy, but im now very curious to compare these results to the reaction i would get from an ingot tainted with 3-5% ZN.???

Exactly. Acid on pure zinc = furious bubbling. Even dilute citric acid will produce small, silvery bubbles on pure zinc.

However, I have not seen anything definitive on what the acid test does to a lead alloy with a small percent zinc. When metals are combined, the resulting alloy will not necessarily have the chemical properties of the constituent metals.

Whether the 'acid test' on zinc-poisoned ww alloy actually works in any kind of definitive way remains to be proven. At this point, the results appear ambiguous.

[mikeystew]

im going to try it monday. melt a small bit of zinc into a mini muffin of WW and give it the acid test.

[jr81452]

I'm interested in reading your results stew. keep us posted.

[mold maker]

I get the same results when testing suspect pewter. after a few minutes there is a slight darkening and a very slight foaming. The area wipes clean and looks as if oxides have been removed.
However with zinc pieces it immediately froths and gives off a gas that darkens the area. The dark stain doesn't wipe off.
If testing a nice piece, be sure to test in an obscure place and use as little acid as possible. I use a very small hypodermic needle to put the acid in a precise place.