Metal Casting Zone

Hello, I am a hobby jewelry maker and have recently decided to take my jewelry making to the next level by creating unique pewter pieces as pendants and charms.
Except I really need help b/c I think I'm doing it all wrong!

I first make the piece out of polymer clay then I have used a silicone pour mold (specifically for low melting point metals) to create a mold for pewter casting. I purchased pewter from rotometals and melted it in a melting pot, then poured the pewter into the silicone mold. The problem?
It came out all pitted and rough like, not shiny or smooth at all. What did I do wrong?
Is it possibly the quality of the pewter? I bought the 92 pewter recommended from their sales rep. Or do you think it could be the mold? Did I miss a step? I'm boggled.
Please help!

Here is the polymer original, the silicone mold, and the messy pewter finished product:

I've only done lead like this and it looks like it may be a cold pour. Do you have a thermometer and did you get it to casting temp? Casting temp is higher than the melting point. You should have gotten a chart from the metal supplier, too hot can cause trouble, also. Other than that, you may try to preheat the mold with a blow dryer or cast several pieces, one right after the other. That's how I do my fishing sinkers and, by the third set, they look pretty good.

I like the piece, keep us posted.

Welcome to the forum!

Hi! Thanks for replying, I was worried I wouldn't hear from anyone, I appreciate it very very much. I am going to try what you said and pour it a hotter. I don't have a thermometer, but the dial on my melting pot is supposed to melt it to about a certain degree according to each number (1-9) , although it doesn't have exact temperature settings either.

I had a suggestion from someone to try a flux paste in the mold. The appearance of the cooled pewter may be from a gassing effect and apparently the flux is supposed to eliminate this? I bought some from Home Depot and I'm gonna try that too. I'm really clueless on this, but I'm learning, and I guess that's what it's all about.

Thanks for the welcome, and also the compliment on my piece, although I don't believe it looks anything like it's supposed to right now, LOL

Any other suggestions would be greatly appreciated. I will keep you updated on the results.

Keep your fingers crossed!

I was referring to the Polymer one.

haha, I figured :o) Thanks, hopefully I will get it cast in pewter just how I imagined it, and you will like it even better then!

Hi Wilczynn


Welcome to the forum. Jammer is quite right Get the mould hot. Try dusting the mould with talc powder before you pour the metal too. Continue to pour the mould 10 to 15 times at the same temp setting on the pot if after 10 to 15 pours the metal is still pitted, up the temp to the next setting and do more pours eventually the surface of the casting should improve. JOHNCAST

Hi Wilczynn

Don't use flux, it looks as though you may have some trapped air.

Is that an open mould (single sided?), if so it's not ideal for pewter casting but there is a trick you can do to improve things. Get something flat that can be heated to above the mould temperature, warm the mould slightly and talc as suggested, it doesn't look like a difficult item to fill so shouldn't require a high temperature. Slightly over fill, give it a quick tap to release any trapped air then press the flat heated item down onto the overfilled metal and keep it there as it solidifies. The extra heat in the flat object should mean that is the last bit to solidify and that will be where all the imperfections are. A 2 part mould should work much better but gravity casting pewter into rubber isn't the easiest of tasks.

Geoff T