Silvercreek Farmer
01-11-2017, 11:45 AM
Ended up with a batch of wheel weights that had be previously picked over by someone else, leaving tons of small clips. Not wanting to pick through for Zn, I tossed them all in the pot and cooked them slowly hoping to prevent contamination. After they melted, I started fishing out the bazillion clips, but while doing so, I noticed more of the alloy stuck to the clips than usual (usually blast with a weed burner, too, but didn't this time). I proceeded to flux with pine shavings in an attempt to clean up the clips and preserve more of my alloy, but it didn't seem to help much. I went ahead and finished skimming to be left with a grainy, slushy alloy that made poor ingots despite being hot.
Fearing Zn contamination, I put some toilet bowl cleaner (20% HCl) on on a particularly grainy sample. Other than some darkening, I didn't see any bubbles, certainly nothing like putting the acid on a known zinc weight.
This morning I remelted the worst ingots, fluxed with pine shavings and skimmed the metallic foam off until I got down to good alloy. Pleased it was not ruined, I repoured the ingots. Then, just out of curiosity, I put the foamy dross in the pot and blasted it with the weed burner until it glowed which did separate the remaining metal from the powdery dross.
So what did I do here? My guess is that the long melt time produced a lot of oxidation, which took a lot of heat to separate from the alloy. Any other thoughts?
Fearing Zn contamination, I put some toilet bowl cleaner (20% HCl) on on a particularly grainy sample. Other than some darkening, I didn't see any bubbles, certainly nothing like putting the acid on a known zinc weight.
This morning I remelted the worst ingots, fluxed with pine shavings and skimmed the metallic foam off until I got down to good alloy. Pleased it was not ruined, I repoured the ingots. Then, just out of curiosity, I put the foamy dross in the pot and blasted it with the weed burner until it glowed which did separate the remaining metal from the powdery dross.
So what did I do here? My guess is that the long melt time produced a lot of oxidation, which took a lot of heat to separate from the alloy. Any other thoughts?