Thank you very much
I'll give you the closer look.
Tin or pewter is a more complicate material than soapstone to work with. It is more expensive, more toxic, more dangerous (liquid metal is hot), but it also holds it's own fascination. Moreover creating moulds for tin figures has the great advantage that once you have a mould ready (creating the moulds is the difficult part) you can relatively easily create several copies of one figure. With a good mould you can easily create hundreds of figures. Of course I don't need hundreds of identical land before time figures, but it is nice to be able to create more than one. Also they make great presents for fellow LBT fans.
To create a tin figure mould the first thing you need is a "positive" that is a figure of which you want to create copies of tin. The positive can be made of almost any material. I am working with a project of a tin figure of Cera using wax as a material, but so far I have only finished her head and body, while the legs are very tricky. For those projects I have finished so far I used positives which I didn't create myself. In case of the first two figures I used two brooches of Littlefoot and Ducky which were produced in 1988 (it was a very lucky catch at ebay. I'm very sure that there must be more figures of Cera, Spike, and possibly Petrie. If any one of you ever gets hold of one of those brooches I offer you the following deal. If you borrow me the brooch so I can make a mould of it you will get not only the brooch but also a tin figure back in return).
The material the moulds are made of is a heat resistant silikone caoutchouc. The stuff is liquid until you mix it with a vulcanizer which causes the caoutchouc to harden within a few minutes. The vulcanizer is very toxic and you must make sure that you put exactly the right amount 3.5% of vulcanizer with the amount of caoutchouc which you calculate by multiplying the specific weight of the caoutchouc with the volume of the mould you want to create. If you put in too much vulcanizer the caoutchouc will harden too quickly to make an accurate mould (even if you put in the right amount you really have to hurry. It would be much better if the hardening took a few hours rather than minutes) if you put in too little vulcanizer parts of the mould will never harden at all rendering the mould useless. The damage cannot be fixed and is very annoying as the caoutchouc is expensive. It is also rather messy to work with, you really need some good soap to get it of your skin and you should put on old cloth, for if it gets on cloth it will stay there. I hope the toxic nature of the volcanizer will serve as an excuse for that ridiculous protection I'm wearing on the following picture taken in January or February 2004 when I was crating my first moulds:
These first moulds were very easy if compared to more complex figures. The reason is that those brooches only had a front side to be used. In this case it was possible to make a form of just one piece (while any figure with front and backside will require at least two parts) by just puting some modelling clay on the back of the brooches, but tooth pricks in and let them dangle in a box with the liquid caoutchouc as shown on the following picture (Littlefoot on the left, Ducky on the right):
As I mentioned before the caoutchouc begins to harden within a few minutes, but one should wait for an hour or two before you remove the positives from the mould. The mould should be put into an oven then and heated from 175 to 250 degrees celsius within two hours, gradually increasing the heat. This step is not absolutely necessary, but it will prolong the livespan of the mould, increase its heat resistance and increase the drying process. Even though the mould is hard after one or two hours one should let it rest for about two days before using it. There is the risk of the form growing unstable if used before it completely dried.
The next picture shows the two molds and the brooches which served as positives:
Before casting the tin the mold should again be heated in the oven. This will improve the fluidity of the liquid metal when cast into the mold. For the same reason the mold is powdered with talcum powder. As for the metal, what I’m using is a mixture of pewter and lead usually in a ratio of 60% to 40%, but the ratio can be varied. Pewter is harder than lead and thus prevents the figure from becoming too soft (so it would be scratched easily). It also has a higher melting temperature than lead which is one of the main reasons to add the lead. Lead is rather soft, and has a lower melting temperature which lessens the strain of the mold when the hot metal is cast in. A drawback of the lead is that it is toxic. Therefore it is important to wash your fingers every time after you touched the metal and to lacquer all the finished figures.
Back then I was still melting the metal over an open flame. Meanwhile I have a tin ladle which can be heated by electricity. Apart from avoiding the risk of fire the electrical ladle is also much cleaner to work with as the open flame produces lots of sooth as you can see on this picture:
At long last the liquid metal is cast into the molds:
and left there for a few minutes to harden. One should wait for some minutes for even if the figure is already hard on the outside it may still remain very crumbly if the core of the figure is still liquid or soft. Not to mention the fact that it’s “smart” not to touch the figure while it is still extremely hot:
It doesn’t take a long time for the figure to cool down enough so it can be taken from the mould. You know this picture already, it is the first LBT tin figure I ever made:
