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Tin Alloy casting. I think the movie says it all, well almost. It is a bit dark in some moments but I hope that those undecided can judge that it is not that hard in the end.
Few words of explanation. Tin alloy I placed in old camping pot and put it on fire in the kitchen. The pot will increase its size as the temperature rises so most probably you will hear some funny noises. After about 5 minutes the tin will start to melt. I switched on the camera at that point so you can see me already stirring it. Final step is simply to delicately pour into the mould.
First few castings will not be good for sure and most probably they will end up back in the pot. The form has to warm itself up I noticed. When it is warmer poured metal does not get cold so fast and has more time to better fit the form.
When the metal settles and becomes solid I open the form. Be careful, it is still quite hot and I using pliers I cut out extras from air channels.
So this is it. In the end I painted one barrel with Revell’s number 9 – matt anthracite colour. Looks quite nice.
Polyester Resin Casting.
In parallel I prepared the form for resin casting. This time I used Symsil M rubber which is extremely elastic for a change.
I took one life boat, bollard, anchor and ventilator - all self built of course.
I used slightly different method for mould building and later casting itself. This time I filled half of the volume with plasticine and squeezed the parts into it. As seen on the picture. Further few steps are exactly the same as with red silicone T-type. You mix correctly with catalyst, mix, de-air and pour. So no point saying anything more. On the following day I remove plasticine part and fill again the silicone after spraying the surface with silicone oil.
When both halves have cured we are ready to cast!
I take 40 grams of polyester resin and mix it with 1g or catalyst. The ratios can be different depending on resin type you use and the make, so always read it the instructions. With polyester resin if you add to much catalyst instead of speeding up the process you will prolong and for days casted part will be ‘sweating’ out the extra catalyst. So try to be precise. One more comment, polyester resins do smell. Make sure you have proper ventilation in your workshop or try to avoid doing it in your room before going to sleep…
Upon mixing the solution I also added 2 drops of black enamel to have some colour of the resin. It can be any enamel as long as it is oil based paint (not acrylic!). Addition of paint makes resin also a bit less fragile. I wait 1-2 minutes so some bigger air bubbles reach the surface and then delicately using wooden stick I start pouring into the moulds. With resin you have about 10 minutes before it will start to gel. It is liquid, liquid and then all of a sudden it becomes a jelly type structure. At this point of time it can become very hot, especially epoxy resins. Never leave extra mixed resin in plastic cup - it will melt!
Few words about the method I used with new mould. Note that, there are no inlets! There are none. I am pouring resin into both halves and am waiting. When resin becomes a jelly I quickly put the mould together! I am sure you will find the moment when to close the mould.
So this is it. Now, I will wait few more hours and will clean the castings:
Just one more shot showing how flexible and elastic Symsil M is. Many items can be casted out of one part mould since it is so easy to take castings out of the rubber.
| RTV Soft Silicone Rubber SYMSIL B |
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| RTV Elastic Silicone Rubber SYMSIL M |
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| RTV Heat Resistant Silicone Rubber SYMSIL T |
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