I am going to make silicon hands for my foam latex puppet. I am wondering which material I should use to make the hands sculpture, which I need more details and smooth skin. I guess it may have two choices:
1. Firm Plasticine (NSP)
2. Super Sculpey
I saw some youtube videos (maybe Claykids) on how to make mold for hands. Their hands are very detailed but the color is more like Super Sculpey.
Does anyone have experience with this?
Monster Clay is good for sculpting fine detail, and is sulphur free. It seems to have more wax in it than most clays. Chavant NSP is also good.
Super Sculpy is a bit different to sculpt with. I find it hard to work with, if you scrape the surface it tends to drag a big piece of the clay along and lose shape, unlike plasticine clays. So I always have to work in two stages. First I make an under-layer and bake it, so it is hard and holds its shape, then I add a small layer of new Sculpy on to the surface to finish the sculpting and get the detail. But many artists do fantastic work with Sculpey and other polymer clays, and get really good surface detail. Maybe with the fingers modelled over wire, you could get a good finish and not have to bake it. I don't know, I have not made small puppet hands with Sculpey, only puppet heads. I am thinking that you want a hard mould of plaster or resin to cast silicone hands in, so you probably want the Sculpey to still be soft when you make the mould, to get it out easily.
Work backwards from the end product. You want silicone (soft) hands. That means a hard mold. If you make a hard mold, it should be against a soft sculpture material. So you would NOT want baked Sculpey.
I recommend plasticine or monster clay. You can use scraping tools and heat gun to melt the sculpture to remove it from the hard mold.
Don't use plasticine, as it contains sulphur and will inhibit the silicone. But Chavant is good, and Monster clay too.
Thank you for these great suggestions!
I will try both: NSP (firm) and Super Sculpey. Luckily I can get both in Toronto.
The reason to try Sculpey is I never worked on it. I watched a lot of 'how to' videos on Youtube. The way to work with it is totally different from plasticine. It is good to have a try. As for hard mold, I think silicon mold with silicon cast works (I remember saw some topics before).
Sculpey firm might be better to work with than super Sculpey.
If you are making a silicon mould for silicon pieces, then use a harder silicone for the mould and make sure to use release agent. But why not use plaster for the mould? Hard plaster or dental stone e.g. Crystal R are good for mould making.
Thank you Simon.
I made some plaster molds before, but I always worry about the details and air bubbles on the surface. While I really saw someone made very detailed plaster molds for silicone. I need more practice I think.
Well, practise on a simple mould first. Here's what you need to do, assuming it is a hand or similar that requires a two part mould.
First you surround the sculpt with soft clay up to the level of halfway. I like to use water clay (which does not seem to cause inhibition problems, but then it does not go near where the silicone goes. The soft clay needs to be flattish, and have some indents in it for keys to make the final mould fit closely together. The other great thing about water clay is that I can brush it away where it meets the sculpt. Take a lot of care so that you do not make marks in the sculpt - this is why I like using hard Chavant, because it is so much harder than water clay. I have also put sculpts in the freezer sometimes to harden the clay!
At this stage, or before, you need to think about the final plaster mould and how you are going to fill it. The way I do arms, there is a piece of square K&S at the forearm position. I use this as a position guide for the armature to sit in the mould. So the water clay comes halfway up this as well.
I use Lego bricks to make walls, but you can use clay if it is thick and fairly solid. If using Lego, make sure to Vaseline the walls generously so the plaster does not go into the bricks. Once you are happy that the mould is ready for the first pour, spray it with some release agent (although this is optional.) Do NOT smeasr Vaseline all over your lovely sculpture!
Many people think that mixing plaster is easy, but it is easy to get it wrong. Assuming you are using the correct plaster, which should be Crystacal R or equivalent, remember that the ratio is about 1 water to 2 1/2 plaster, so never fill your mixing tub more than about a quarter full with water. Water goes in first, then sprikle on the plaster. You will need to sprinkle far more than you think you need. Make a little hill in the middle with it, then watch as the water gets absorbed. Don't start mixing straight away as this entrains air bubbles. You should get it to a thick yoghurt or custard consistency. Now take a soft brush and brush plaster into the deep cracks and folds and joins, anywhere that it will not easily pour. Pour a bit of plaster, then brush more quickly over the general details. If you have strong lungs, you can also blow on the plaster, and knock the mould several times to get those air bubbles out. Then pour about half the rest of the plaster in. Add some glass fibres or some burlap (hessian), then pour the rest or up to the top of the mould. It is always good to get a nice flat top, as you may need to rest the mould when open.
Make sure you wash that brush before the plaster sets! And don't pour any plaster down the sink. Just let it set in a bowl, pour off the water and crack out the set plaster into the bin.
When the first half is set and cool and really solid, take off the walls, turn the mould upside down and remove the water clay carefully, not disturbing the sculpt. You should end up with a hand half embedded in plaster. Now you need to add some pry spaces - just some little flat lumps of clay at a couple of places around the edges wher you will get a flat screwdriver in to pry open the mould when filled with silicone. And mix some water clay with water to make a slip, a very thin clay that you can brush on as release agent. Any plaster that does not get this coating will stick to the other half and cause problems. But you can check for this by making sure there is nowhere that remains brilliant white. I also like to spray some release agent at this stage too.
Build up the walls again, this time putting some sausages of water clay around the edges to seal them against the LEGO bricks. Don't forget the vertical inside corners. Then pour the second half of the mould as per the first.
You will soon become an expert, learn from the mistakes. You will also save money as a big bag of plaster lasts for ages. Good luck!