Zn based type metal?

I was alloying some soft lead with type metal (letters) I've had for a long time. As I'm impatient, I use a small propane torch to supliment the 4000 watts of heat from the bottom of the pot. Some of the type metal melted as I would expect, and some of it "boiled" and popped. The result was a foamy layer on top of the melt which I quickly removed. I then grabbed a few letters and melted them. One bubbled and spit as a few in the pot had. The image below is the solidified bubbles.

Has anyone ever heard of zinc based type metal??? If no, has anyone ever seen this behavior in "good" metal?https://uploads.tapatalk-cdn.com/201...be1ecaa84e.jpg

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Do you suppose that the oil based printers ink just needed time to get to temp and off gas? Perhaps the tinsel fairy was just blowing you kisses. Type metal has a high antimony content and you probably just skimmed off a lot of good antimony that would have gone into solution if you had taken your time and not been impatient. Did you use anything to reduce the oxides? Probably not, if you were in such a big hurry. Try it again without the torch.

Seen something like that when the metal going in the pot was cold....think of a "sweating" cold can of soda on a hot day.

yep, throw the " oatmeal" back in, along with a good amount of sawdust, and some wax will help too, but watch out! it will burst into flames! I just let it burn out, that usually works good, you may have to do it twice, since you are re-introducing it to the mix, I am just guessing. good luck! ( and be a bit more patient!)

All else fails do the acid test!

My melt was at casting temp (665) and the sponge remained. I flux with beeswax but have recently had a "free lead" source turn out to be highly zinc contaminated, like mostly zinc with a lead impurity, and it showed the same type of behavior which made me more sensitive...

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I have not seen Zinc in type metal. Not saying it can't happen, just have never seen nor heard of it. The ink burning out may be a culprit. Maybe try the letters only in a cold pot and then turn the pot on. High Antimony can have that oatmeal appearance sometimes.

When you are blending in the type metal or any high antimony alloy you probably will need to bump up the heat and after blending it well, along with the reduce and flux, you can turn it down to a casting temp. I cast about 725 unless I am casting large and heavy bullets.

Is your “type” individual letters or linotype “lines-o’type”?

Rarely if never was mono and handset type pieces cast in Zn.

But someone somewhere could have tried making lino setting strips out of Zn. Never seen it, but Zn casts very well!!!!!! Zn is used to cast a ton of stuff today.

The metal is in the form of letters, so I had assumed a type metal of some sort. I'll try bumping the temperature up to see if it incorporates better.

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I have found Zn single letters that did not melt at 700 deg F and reacted to the acid test. These letters had one square notch on the side, not like the round notch as found on Mono and Foundry type. There was about 2 lb of these in a 50 lb box of Mono type metal I bought on flea bay.

I've never seen zinc in type before. Like BNE said, don't mean it can't happen. I guess nothing is sacred anymore! Like Mary said, do a quick acid test on the suspecting lead before you throw it out or mix it with something else.

Zinc will make an oatmeal like slush but I never saw bubbles like that.
I think you just did not get it hot enough. What are you using for a thermometer and can you really trust it?

Quote:

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Originally Posted by lwknight

Zinc will make an oatmeal like slush but I never saw bubbles like that.
I think you just did not get it hot enough. What are you using for a thermometer and can you really trust it?

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Pretty sure i can trust it, type J thermocouple to my electronic controller. IR temp gun is within a few degrees when I remember to adjust the emissivity properly.

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I've had 'oatmeal sludge' forming on a melt that should not have any zinc in - twice. I scooped it all off and the remainder was fine.

On fluxes, the best flux I have found is stearic acid. One can use it as a solder flux too which I do when alloying copper into the pot. I tin the copper with tin then hold it under while the copper dissolves. Stearic acid is a wax by the way.