Alloy content and frosted Bullets

[waco]

Does the Sn and Sb content of the alloy contributed to getting frosted Bullets or is it strictly a temperature thing regardless of alloy? Sometimes it seems I can’t run stuff hot/fast enough to get them frosted. Usually mystery alloy too(wheel weightish?..)

 

[fiver]

yes.....

 

[USSR]

no..... (have no idea as to what I'm saying no to)

Don

 

[462]

Good thing you asked only two questions -- who knows what kind of answer you would've got.

 

[Cherokee]

In my experience, the closer you are to pure lead, the less chance of frosting. That should get the discussion going.

 

[S Mac]

I agree with that, and would add that ambient temp also seems to play a part, colder temps= more frosting. At least that's my theory.

 

[Winelover]

When I had access to tool & die lead, I use to get frosting, quite a bit. I use to cut it with pure, 50-50. Don't know the composition of it. Was moderately hard and didn't shrink much...........a quality the die sinkers need. They used it to test finished moulds for engine/ piston connecting rods.

 

[RicinYakima]

IMO, frosting is from two things; slow cooling bullets and more antimony than tin in the alloy. At less than 5% tin and antimony, as the bullet cools first the antimony solidifies, then the bi-metal tin/antimony and lastly the lead. If the iron mould is hot, the antimony forms the dendrite trees larger before the tin/antimony crystals form around it. Then any remaining tin/lead encloses the bullet.

I have few aluminum moulds, so don't have much experience with them. Brass and bronze mould have less frosting appearances.

I like frosty handgun bullets, as there is less chances of leading if you go to heavy on the powder.

 

[Ian]

Questions too fuzzy.

Answer: antimony in excess of tin as Ric explained. Only happens when mould blocks exceed a certain temperature which slows bullet cooling rate to a certain point. The temperature of the alloy in the pot has nothing to do with it.

 

[Mitty38]

I am very inexperienced . But just to put my 2 cents in, the only time I ever got frosting was with a steel 2 cavity and COWW's. But started swiping on a damp rag every 3rd and it stopped. Antimony in excess of tin, and also temp, both might explain that.
I think the mould may have something to do with it too.

 

[CWLONGSHOT]

Whats wrong with frosty bullets???

 

[waco]

Whats wrong with frosty bullets???

Nothing. I was trying to get them that way and was unsuccessful that casting session.

 

[CWLONGSHOT]

These where aweful frosty... Can ya tell? ME EITHER!

 

[johnc]

IMO, frosting is from two things; slow cooling bullets and more antimony than tin in the alloy. At less than 5% tin and antimony, as the bullet cools first the antimony solidifies, then the bi-metal tin/antimony and lastly the lead. If the iron mould is hot, the antimony forms the dendrite trees larger before the tin/antimony crystals form around it. Then any remaining tin/lead encloses the bullet.

I have few aluminum moulds, so don't have much experience with them. Brass and bronze mould have less frosting appearances.

I like frosty handgun bullets, as there is less chances of leading if you go to heavy on the powder.

are those trees anything like oak and mesquite and pine?

 

[DHD]

Nothing. I was trying to get them that way and was unsuccessful that casting session.

That's my luck too. Not that I try to get frosty but I'll go a couple sessions without seeing any, then I start seeing them every cast. In my case this is when using an Accurate Mold in aluminum. The frosty bullets are about as perfect as I can cast and the alloy would be COWW and pure with some tin added. This particular batch of COWW was a 500 lb batch and was hard as woodpecker lips so I suspect it contains quite a bit of antimony.

 

[RicinYakima]

are those trees anything like oak and mesquite and pine?

After you slice, polish and acid etch, they look most like pine trees under the microscope. FWIW

 

[Joshua]

Mold temp is the only thing that I have noticed that gives me frosty bullets. I still try to cast pretty fast. I was casting with only one mold at a time and tying to control mold temp with a wet rag. I was still getting frosty bullets. I wasn’t cooling enough.

Now I’m casting with two molds. Most of the bullets will just start to frost, but not excessively.

Almost all of my lead is mystery lead that I hardness test with pencils. So, I really have no idea about the alloy vs mold temp?

 

[Mitty38]

These where aweful frosty... Can ya tell? ME EITHER!

View attachment 19512

HA HA
Looks like you have more problems then just frosting. Some serious copper oxide forming on the outside of those bullets.

 

[Mitty38]

FYI:
Dendrite trees is a biological term, originally. It refers to the branching out of human nerves and creating a structure that is intertwined with other tissue.
It has a very distinctive pattern like a tree. As opposed to a snow flake or spider web, scale, so forth.
This Word actually means tree, if you trace it back to its roots. (Tree, Roots, Ha I kill myself)
It also has often been used informally, in metallurgical fields to describe a certain appearance of some crystalline structures, in metal.

 

[Ian]

My dendrites grew a schwannoma.