So, how much Zn is too much?

[HammerMTB]

I sorted all me weights. I stay by the smelting pot, watching for the occasional one I missed.
Today, 'bout the 4th pot I smelted down, appeared a lone "non-melter" As I scooped it up, one end liquified and left the rest. To my horror, it was a zincer-stinker. It was about a 4 oz weight, and a little less than 1/2 of it melted into the pot. I quarantined the pot full.
So, is 1.5-2 oz in 30-40 lbs enough to be concerned about?
That'd be 3-4% or so, if I did my figgerin' right.

[Ronbo256]

if you melted 1.5 oz of zinc in 30 lbs of WW, that's .3125 percent if I do the math right. I wouldn't worry about it, but I would keep that 30 lbs separate for to cast for hard stuff. You could try the sulfur trick to remove the zinc.

[fecmech]

Try and cast with it. I screwed up a melt worse than that and it works fine. I just grabbed a ladle and a lee mold and cast some out of the smelt pot to try. They turned out fine so I used the rest of the 40+ lbs for casting. A little zinc IMO is not the end of the world.

[HammerMTB]

Excellent!
I may try it all alone in a pot, and see if it casts OK.
Or, I may throw a single lb in the pot now and then and consider the quantity too small to concern me.
Thanks for the replys!

[sqlbullet]

Somebody (not me) oughta take one for the team and work up some numbers on when it becomes too much zinc. You know cast, add zinc, cast, repeat until the bullets won't fill out and report their results.

I also think it may matter some what you are casting. I suspect smaller boolits don't tolerate zinc as well.

[DLCTEX]

Lyman's Cast Bullet Handbook says up to 2% zinc can be alloyed in. Any more will separate out. I have cast many boolits with it and find they work OK. Some have said that they get more brittle with age, but when first cast they are very malleable, hammering flat without breaking.

[williamwaco]

I have a 20 pound Lee Pot.
It really contains about 16 pounds of wheel weights leaving room to stir without sloshing metal out of the pot.

I don't know the weight, but ONE, ( 1 ) zinc wheel weight the size of your index finger will contaminate the entire pot. If you add 16 pounds of good weel weights to that, you will get 32 pounds of contaminated metal. DO NOT ADD GOOD METAL TO TRY TO DILUTE IT. IT WILL NOT WORK.

Now the good news. Keep that contaminated metal segregated but use it. It will cast good bullets. It is more trouble to flux and keep clean but you can make good bullets with it.

If you want to read more, there are several lengthy threads on this site about zinc contamination.

Search for zinc contamination and also for "oatmeal" ( not in the same search. The search function is not that smart.)