How much Zinc is too much?

Twas melting wheel weights, the first batch came out oatmeal and had only the tiniest bit of a zinc wheel weight not melted.

The second batch was OK but had the tip of a zinc melted in.

If I try to add more good lead to the first batch, can I get under the magic percentage?

Spotys

You "tip" of a weight is nothing! Don't take this Zn thing that seriously!

I have tested lead up to 5% Zn with virtually no problems except boolits are a bit lighter and you need to add more Sn to lower the surface tension to get fill-out in your boolit molds.

5% is a LOT of WW's! You would have to intensionally miss a bunch in your sorting to get to that level.

Don't let the big bad zinc monster scare you!

banger

Try fluxing the poop out of it, I use sawdust. if you can get most of the sludge out, the rest of the alloy should be salvageable. It takes more than a single ww to corrupt an entire 25-30# batch IME.

IMO, a difficult question to answer. Difficult, since I don't know how much zinc, either by weight, or percentage of the total weight is in a pot.

I do know that on the two occasion that zinc has snuck into a pot, it completely screwed up that pot for casting. Since I'm not a metallurgist, and don't play one on TV, I had no cure. Both pots were a loss.

Now I carefully scrutinize any wheel weight that goes into my "keep" bucket. I mention wheel weight, as I only have the problem when casting WW alloy.

Based on the above, any zinc is too much.

MichiganMike

Seeing how copper is twice as hard as zinc, IMHO zinc can't be that bad for your guns. But zinc will require more tin to help with fill out in the mold.

I think small amount of zinc in alloy will change the temperature that yields a good liquid melt. I have had "sludge" on top that was not due to zinc but just the melt was a little cool. Don't know how much zinc it would take to change the temperature required to have melt in a good liquid state for casting.

Perhaps those that have done more with zinc would have an idea of what temperature would work best. You might be fine if you crank up the heat a bit.

2% zinc will alloy with lead. Any more will cause oatmeal slush.

It is a problem when it is. Why sweat it if your bullets are casting well.

Some work has been done with casting bullets out of zinc and the bullets were very hard. In one experiment the same bullet was recovered a number of times from a wooden log and reloaded and fired several times. If you are not into that then the concern centers around how much zinc can be present before it interferes with the alloy and casting good bullets. I personally don't know so can't pin down a percentage. From my own experience, zinc which seems to come from WW metal is a pain in the butt and if it has contaminated the alloy to a nuisance amount will prevent bullets from filling out properly and cause frosted spots until you can get its level down. One recommendation is too try and dilute it by adding "good metal" to the alloy. A lot of repeated fluxing may also work. It is not bad for your gun(s), but it (in an objectionable amount) definitely is not fun to try and cast decent bullets out of. You can salvage contaminated alloy, but it takes a bit of work. LLS