Need Help -- new brass mold

I just received a new .715 brass mold from Tanner, and decided to try it out.

I cooked some pure lead, heated the mold and went at it. I managed to cast a half-dozen balls that were useable and then a rolling fustercluck started. A small bit of allow got into the mold and solidified in the bottom of the seal between the two halves. Soon, I had wing forming on the bullets from lack of a good seal, and nothing I did could get it to stop-- just make it worse. Pretty soon, I couldn't keep a seal on the mold and I was leaking.

I figured somebody here would know what to do, so I poured out the rest of the alloy into ingots and came in.

What do I do to get the alloy cleaned off the mold?

While it's hot, take a lead pencil and work it off.

Cool. Thanks for the quick comeback.

Alloy, or lead? If it's pure lead (and I guess it was), it's much softer than brass. You can scrape it off with a popsicle stick, toothpick, bamboo skewer, or other wooden stick. If you have vent lines to clean, use a sharpened stick. Wood won't hurt brass. It will also be easier if you get the mold to casting temp first (either by casting a while, or using a mold oven/hot plate), but it does make it trickier to hold, as you have to use thick gloves as you work on it.


If it was some alloy and you have tinning on the mold, use a bit of beeswax melted over the spot while it's casting-temp hot and rub with a stick and/or heavy denim or burlap. Beeswax won't help pure lead.

I took out a carpenter's pencil, a normal #2 pencil and a bamboo skewer. The mold cleaned right up. Thanks all!

I'm back in the house with a big handful of big shiny balls and a feeling like I've accomplished something.

Make sure you don't run that brass mold too hot or you can "Tin" the mold with the molten lead.
I did this with the first brass mold I ever bought on the first time I used it. :(

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Originally Posted by lar45

Make sure you don't run that brass mold too hot or you can "Tin" the mold with the molten lead.
I did this with the first brass mold I ever bought on the first time I used it. :(

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Hmmm....That's never crossed my mind. I've ended up with wings on a few boolits from a couple of my moulds that once in a while don't like to close unless I'm careful, but never noticed any tinning.
Do you have any idea how hot that would be? Any warning signs? Does the alloy make a little bit of difference? I start with my mould too cold (of course), when it's up to temperature I can kinda guage it by the frost/no frost/heavy frost on the bootlits. I usually aim for no hotter than just a gray color, a little hotter if that's what it takes to get the boolits to fall out. Just a little past the too cold/wrinkles/bright and shiny that you get when you first start. As soon as the wrinkles are gone and I've got sharp edges, that's where I like to stay. If the sprue takes longer to freeze, I'll also slow down. I don't have a thermometer, I just run things by "feel".

I think I was just running it too fast and way too hot. I had lead smeared on the top of the blocks. I tried a razor blade, sand paper on a granite block...
It was an expensive lesson, lol
I get along with brass molds just fine now, and always lube the top of the molds.

If you use a lot of tin in your alloy, tinning can be a bigger problem.

After I got the smear of tinsel off the mold things started to work much better. I got 2 dozen cast fairly fast.

I have to say that there is something quite satisfying in casting large .70-something round balls. It goes rather slowly in that it takes a while to cool off enough to pop the ball out. However, when I opened the mold, I was invariably met with my own reflection in a shiny perfect orb.

In this modern , computerized , PID controlled day and age ... it's important to keep a few simple things around like a Carpenters Pencil , #2 writing Pencil and a small stick .

There ain't no Smart Phone App to get a mould clean is there .

Shaman ... ATTABOY ! Keep On Keeping On my Man .
Gary :drinks:

I generally use a 1x2" stick as a mallet. The flat edge will scrape off any excess lead and I've used it many times.