what zinc in melt look like.

[arcticbreeze]

I was casting some boolits this afternoon and my normal procedure is to run a lee 20lb bottom pour and a Lyman 10lb mini-mag to refill from. I always refill the bottom pour pot as soon as two of my gravy type ladles (probably 2lbs per ladle)will fit as to minimize temp variation. Well this procedure has always worked perfect for me. As soon as I went into a new and unknown batch of ingots (supposedly WWs acquired from a guy at the range I go to) I started to get fill out problems and they just don't look right. Partly frosted and partly shiny on the same boolit. I don't believe it is temp because I have been doing it this way for the last year with no problems. I don't believe it is contamination of the cavity because didn't lube or anything between the good boolits and the bad ones.

[docone31]

I get that sometimes.
I believe it needs to be blended more, or stirred more.
Alloy is thicker than water.

[Down South]

The zinc contamination that I’ve dealt with causes the melt to look like oatmeal on top. It did cause frosty spots on the boolits and the boolits had poor fill out in the frosty areas. I’d try fluxing and a lot of stirring and see if it helps. Maybe it ain’t zinc.

[JIMinPHX]

There was a post that showed pictures of pots that had been contaminated with zinc. If you do a search, you might find it.

[armyrat1970]

Frosted bullets is not a product of zinc contamination. It maybe that your temps were a little high but frosted bullets will shoot just fine. If your mold is not filling properly it could be some zinc contamination. You may get rounded edges where they should be sharp. Smelt in a different source and not in your furnace. Keep your temps around 680 to 700. Zinc does not melt at these temps and any can or should be able to be removed with the rest of the dross and clips. Pour you ingots and then use your ingots in your furnace to cast. If you don't have a thermometer for smelting Wheelweights get one.
Had a problem with wheelweights awhile back containing zinc and it was a PITA to get my furnace cleaned. You cannot cast good bullets with any zinc contamination.
Read some of the stickys concerning zinc. A lot of good info there.

[Alloy]

Historically I have melted + 600 lbs WWs (wood fire), removed clips, oiled sawdust fluxed molten WW alloy, blended back pre determined amounts of type metal (lino, foundry) with 95/5 solder, fluxed again creating a bulk, lot of a prescribed alloy. This method has served me well for over 15 yrs. providing uniform quality bulk alloy.

Unfortunately with the ever increasing amount of zinc (Zn) WWs and my poor temperature control I have recently experienced what I believe to be Zn contamination for the first time using this bulk alloying technique.

I have discovered partially melted WWs in the clips I skim from the WW melt. In some cases these partially melted WW's are composed of a very silver / bluish tint metal. I assume some of the metal (I suspect Zn) has melted into the Pb / Sb / Sn alloy.

I ladle from a Lyman Mag Dipper 20 and have done so for + 20 yrs running tons of alloy blended in the above described manner without symptoms of contamination.

Symptoms of what I believe is contaminated alloy are:

Cool (room temperature) metal appears more mallable less brittle than non contaminated alloy of similar composition.

I see more rapid solidification of metal atop of sprue plate (almost instantaneous) no matter what the casting temperature is as opposed to slower solidification with non contaminated metal.

Incomplete fill out of bullet lube groves at any furnace temperature. This condition does not go away with higher casting temperature.

Alloy has very high luster (more silver than non contaminated metal) with bullets showing spots of frosting at higher temperatures as opposed to complete frosting at high temperatures with non contaminated alloys.

It appears my only recourse is to melt much smaller lots under controlled temperature and skim off all Iron (Fe) and Zn WWs before the Zn reaches its melting point. The last 100 lbs of WW's I received had over 20 lbs of identifiable Zn WWs.

My WW sources tell me the era of Pb / Sb / Sn WWs is comming to a close with the substitution of Zn and Fe becomming more common daily.

[armyrat1970]

Historically I have melted + 600 lbs WWs (wood fire), removed clips, oiled sawdust fluxed molten WW alloy, blended back pre determined amounts of type metal (lino, foundry) with 95/5 solder, fluxed again creating a bulk, lot of a prescribed alloy. This method has served me well for over 15 yrs. providing uniform quality bulk alloy.

Unfortunately with the ever increasing amount of zinc (Zn) WWs and my poor temperature control I have recently experienced what I believe to be Zn contamination for the first time using this bulk alloying technique.

I have discovered partially melted WWs in the clips I skim from the WW melt. In some cases these partially melted WW's are composed of a very silver / bluish tint metal. I assume some of the metal (I suspect Zn) has melted into the Pb / Sb / Sn alloy.

I ladle from a Lyman Mag Dipper 20 and have done so for + 20 yrs running tons of alloy blended in the above described manner without symptoms of contamination.

Symptoms of what I believe is contaminated alloy are:

Cool (room temperature) metal appears more mallable less brittle than non contaminated alloy of similar composition.

I see more rapid solidification of metal atop of sprue plate (almost instantaneous) no matter what the casting temperature is as opposed to slower solidification with non contaminated metal.

Incomplete fill out of bullet lube groves at any furnace temperature. This condition does not go away with higher casting temperature.

Alloy has very high luster (more silver than non contaminated metal) with bullets showing spots of frosting at higher temperatures as opposed to complete frosting at high temperatures with non contaminated alloys.

It appears my only recourse is to melt much smaller lots under controlled temperature and skim off all Iron (Fe) and Zn WWs before the Zn reaches its melting point. The last 100 lbs of WW's I received had over 20 lbs of identifiable Zn WWs.

My WW sources tell me the era of Pb / Sb / Sn WWs is comming to a close with the substitution of Zn and Fe becomming more common daily.

It is sad. Don't know if it is an evironmentalist thing but some of the newer weights are containing zinc mix instead of pure lead. Keep your temps between 680 and 700 and you should be able to skim the zinc off of the top of the melt. Iron, Zinc and steel will not melt below 700F.