Liquid Mold Silicone

Which type to get

The difference between mold silicone hard S40, medium S30 and soft S15 is the hardness. S40, S30 and S15 refer to the shore scale, which tells about the hardness of the silicone. The higher the shore value, the harder, down-shape-stable silicone mold you get. The silicones are just as liquid when they are mixed up, and it is only with the hardened silicone that you can feel the difference in the hardness. When choosing which mold silicone is best for you, look at the item you want to cast. If you want to cast a figure with many negative slips, choose the softest silicone, Soft S15. An example of negative slip could be a casting of a head where the neck itself is narrower than the head. Here, the hole (neck) your casting has to go through will have to be smaller than the head, and it would therefore be best to choose a soft silicone with good flexibility, so that the shape can give way when the head has to be pulled through. A shape completely without negative release could e.g. be a pyramid.

Note that a cast of a head would most often be made by dividing the mold, thus avoiding the negative slip, but since you can´t divide all mold for all figures in order to avoid negative slip, it is still important to consider which hardness is best suits for the mold. If you want to cast softer items, e.g. stearin or soap, it is also an advantage with a softer silicone.

To get as stable molds as possible, however, always go for the hardest possible silicone that fits what you want to cast. Liquid Mold Silicone – Medium S30 is a good all-round silicone that could be used for most tasks, and Liquid Mold Silicone – Hard S40 is good for tasks where you have use for more dimensional stability. If making impressions from bark, trees and wood use the Liquid Mold Silicone – Hard S40.