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Hi everyone,
i gained some experience casting miniatures with resin.
I now turned to tin, which i mix up with antimony. So far, so good: The problem is, that many details of the miniature get lost. I made lots of experiments, varying the percentages of the single metals in the alloy, but though i didnt get satisfying results.
Have you succeeded casting really good miniatures? Which alloy did you use? So far i would say, the tin is no comparison to resin concering the results. I would like someone with experience to exchange them.
So long..

If you're going to cast in metal, you'll need access to the professional equipment used by ring makers. This includes the ubiquitous centrifuge, which spins metal into molds at a high velocity while drawing out any trapped air.

Games Workshop uses centrifuges to cast about 20 models (more or less depending on model size) at a time in large circular silicone molds. Formerly they used rubber molds (which look and smell like automobile tires), but these are more easily ruined than silicone if the castings are taken out before the metal alloy has time to cool. The problem here is to get the temperature of the metal just right. If the metal is too hot, it will melt the silicone. If the metal is too cold, the castings will be malformed.

Deatil can be affected when using metals.

What are you using to create your moulds?

What kind of tin/metal is it that you are using?

White metal comes in different grades, each with slightly different properties.
Check out how you have sculpted your miniature and look at how it os positioned within the mould. Undercuts can hamper your ability to get high detail and any awkwardly positioned items may make it difficult to get metal into any gaps.

I have had acceptable results handcasting at home using metal, so don't give up.

using fields metal may help. Its very low melting temp will allow you to heat a higher percentage above melting point to allow more time to cool in the mold.

Heat your molds in the oven before casting.

It is possible to MAKE a centrifuge, but I would be remiss in giving you advise for doing it over the internet, and I would extensively test it with water and/or resin before putting molten metal inside.

Thanks for your replies.
My moulds are made of RTV heatresistent silicone (the red stuff).
My alloy consits of:
Tin (99,95%)
Antimony (99,95%)
I mixed up the tin with about 10% antimony and about 2-3% in another alloy.
I didnt know GW was using centrifuges. So is there a chance to ever create miniatures with a similar detailedness?
I assume my problem comes from the alloy, the undercuts are no problem so far. I also heat up the moulds before casting.

is the other element bismuth by chance? or perhaps copper?
If memory serves me Antimony melts at over 1100 F, Tin at about 450

A common casting alloy of 92%tin 7% antimony and 1% Copper melts at 500-550 F thats pretty friggin hot!

Even old Britannic pewter 92% tin 7.75% antimony and .25% copper melts just under 480 F

60% tin and 40% bismuth will get you under 350F

An alloy prince august sells is 94.5% Tin / 3% Zinc / 2.5% Antimony it still melts at 450F but at least its suggested by a tin soldiers company.

I genuinely suggest looking to move your melting point down for the reason stated in my previous post.

Perhaps making a gate with a very large area for excess metal so you can over pour and use the weight of the material to push the metal into the detial.


Automatically Appended Next Post:
Sorry I forgot to say it sound like your alloy would melt real close to 600F or more.
If you bought a lot of tin I would say reduce the antimony, introduce bismuth in increasing percentages.
If your investment is still low I recommend trying a small quantity of fields metal which is bismuth and indium primarily and melts under 150 F

I cant use Copper for its melting point is so high, i cant reach it with my simple equipment.
I also considered mixing bismut into the alloy. I thought, maybe the high amount of antiomony of 10% in the alloy would cause the metal to expand while cooling down, thereby pushing against the mould and deform it, so the details get lost.
I just thought, GW would only use tin and antimony, too. But their miniatures are much more detailled than my own creations.

There may be alternatives in your area.

but.
http://www.tiranti.co.uk/subdivision_product_list.asp?Content=LF+No+3+Low+Melt+Alloy+%2D+White+Metal+%2F+Tin+Alloys+%2D+Casting&Subcategory=63&Subdivision=248

A very low melting lead free tin alloy. It is used for castings that have thin flat surfaces, and having very good flow properties reproduces the finest detail. It has similar uses to our NO 3 alloy, but being lead free it is also good for jewellery and jewellery components. Contains Tin / Bismuth.
MP = 138ºC
SOT = 150ºC to 180ºC

Could be what you are looking for. GW uses similar.

I have tried different alloys now, that also contain bismuth. The results are not satisfying, though.
Does anyone know a good composition of the different metals?
Maybe someone even tried mass spectrometry to analyze the miniatures?

I used to use a 60/30/10 mix of tin, antimony and bismuth from a local casting shop (ingots were available for sale) and it gave pretty good results for a gravity cast (non-spincast) in a two-part (red) head resistant RTV silicone mould.

Haven't cast in a metal that isn't bronze in over 10 years though.

I had exactly the same problem when casting tin in red RTV silicone. I was using lead-free solder, which is >99% pure tin.

After a LOT of experimentation the solution turned out to be to use 20% bismuth / 80% tin, turn my pot up to max temp, and pour it as fast as possible. Just FYI.

As its been 11 years I think they may have fixed their issue by now.