Question About Solder-Casting

[a438980]

I have one of the plastic Pirates of the Caribbean mayan coins that looks like gold plastic and was thinking about using some kind of mould to make a copy of it out of solder that I could then paint with gold leaf paint for a more authentic look but I'm worried about losing the details and about how stable to coin would end up being. If it works well enough I may try to make a mould to recreate the copper bones key from The Goonies. Does anyone with experience casting with solder have any tips, hints, or suggestions for a first-timer?

 

[Nixon]

Cold casting in resin might be easier http://www.smooth-on.com/gallery.php?galleryid=312

 

[Darth Lars]

You don't cast in solder but in tin/pewter. Solder alloys are made for soldering, pewter casting alloys are made for casting. Pewter could also be melted on a hot stove (I would prefer to use a separate hot plate than the one in my kitchen..)
You can use heat-resistant RVT silicone for pewter. It must be a heat-resistant kind, or the mould will burn when you pour the metal. Real metal could be plated with real gold if you like.
Ladles and casting alloys are sometimes found in model building stores, stores for role playing games or even some toy stores

"Cold-casting" metal is safer and simpler, though. Dust the mould with powder. Shake off the excess. Pour resin. You could also mix up to 50% powder into the resin, but the more you have the more brittle it would be.

 

[bookface]

Yep, go with cold casting. Get yourself some steel wool and a decent metal polish and they will look way better than something with gold leaf paint. I would also echo what has been said about not trying to use solder to cast, it's not a casting material. Use the appropriate material for the job.

 

[a438980]

I really appreciate this, and the link from Nixon is definitely going to help. Cold casting is without a doubt sounding like the best way to go with the Goonies "Copper Bones" key since only one side needs to be very detailed. Since the Pirates of the Caribbean coin is two-sided and detailed without any large spots that can be left open to pour the liquid into does anyone have any techniques they can suggest to get a clean, bubble-free, seamless casting done of this?
Also, if for authenticity sake I was considering just making a "Copper Bones" mould and melting real copper from a hardware or craft store into it, are there any tips anyone would have for doing something like that?

 

[bookface]

If this is your first time casting anything (you don't say, but I'm assuming you're not super experienced), then my advice regarding casting copper, is not to. Copper has a melting point of something like 2000°F, which is about the same as gold and will need specialised equipment and can go badly wrong. You're trying to pole vault before you can walk here.

Regarding casting a coin, you need a two piece mould. Check out this video http://www.youtube.com/watch?v=FQ1A7ZjTsx8 which walks through the process and follows up with a casting one. The model they use is a sphere, but the principle is the same.

 

[a438980]

I've been too busy with school & work to focus on this for awhile but I'm going to try working on these sometime soon. I found the right powder to give the coin the right look, but I still want to figure out some way to make the copper bones key out of real copper. I know hardware stores have copper soldering wire. Would there be a downside to just making a mould and melting copper into it with a blowtorch?

 

[Darth Lars]

I doubt that you would be able to get that temperature with a simple blow torch.. and there is no silicone that would survive that temperature.

I think a more accurate material for the The Goonies key would be bronze, and the method "lost-wax casting". There are many artists around the world who sculpt statues of all sizes to be cast using that method. If you are serious you should find a professional to do it for you.

Yet another method would be to cut and engrave it in a block of aluminium and get that plated.