Metal Casting Zone

I'm trying to cast small pewter medallians with detail similar to a state seal; an image with lettering around. I've tried rtv molds but they provide no detail, maybe a gas venting problem? Also tried sand mold which was a bit more successful but left a grainey texture and some detail loss.
I have no high temp facilities at this time so I'm limited to low temp alloys.
Any suggestions or comments on how to accomplish this project?
Thanks,

These low temp melters are cast commercialy in Silicon rubber molds using a centrifugal method. See Cast Tin for some of the supplies and equipment for this.

Good luck and happy melting

Hi Buddy you should be able to cast your medallians with all the detail you want in a quality RTV silicon dont buy a cheap one splash out on a good one ask the vendor and they should be able to put you onto something that will do the job.

Your medals should be easy to cast and get the detail your after I use silicon all the time and I have to be extremely careful with my masters to make sure there are no fingerprints on them or the silicon will pick it up.

Failing that mate I would suggest going to see a spincaster they will make them for you but you will have to pay a bit for them.

I have a spin casting machine myself so I can say it will cast your medals easily enough.

When using RTV silicons sit down and put some thought intohow you are going to make your mould if you are not confident ask for help from someone else.

or you can ask me I have a casting business and I use the stuff everyday.

Have you thought about why the RTV silicon you used could not give you the detail you were after simple buddy.

It was either the wrong product for the job or it was just to bloody thick viscosity plays a big part in how a silicon mould will pick up your detail I get amazing detail out of silicon moulds so there is no reason you cant as well.

for best results I tend to use a wax spray on my masters before I pour the silicon on them then I vibrate my moulds so they release any trapped air.

I believe Barnes Has some very good silicons that would do your medals no sweat if you are not after many medals a product called pinkysil would do and is very fast setting.

RTV silicon have changed and you can now find one for most low melt applications.

I have cast a few pieces similar to what it sounds your attempting with varying results as well. I have found that a good mold made from a decent silicone will easily produce the detail you are looking for. You may want to try brushing the silicone over the detail first to ensure it seeps in around the detail.

Also if it is air bubbles causing the detail issues you may want to look into a vacuum chamber for removing the air prior to the silicone pour. Or you can always pour the silicone from a decent height and vibrate the mold box to remove the air. I have also found that to be a good alternative to the vacuum chamber.