A silicone mould may be less suitable for dimensionally stable products. In addition, poor quality silicones (often cheap) with a high fat content can give off, which is sometimes visible on the A1 object.
Moulds made of sheet material such as epoxy plywood forms or polyester moulds work well in practice if provided with a suitable release agent. During hardening, A1 expands slightly. This can cause A1 to get stuck in the mould, especially when it is not self-discharging. Moulds made of gypsum or other porous materials are not recommended unless they have a fully sealing coating or washing system that prevents moisture from the A1 from penetrating into the mould. There is a risk of a (strong) bond between the mould and the A1 and a weakening of the A1 object.
When using a release agent, (limited) release agent may remain on the A1 object after release. Often these release agents are based on fat/oil. This can affect the adhesion of even finishing coats such as A1 Sealer PLUS, paint system or an extra layer A1.
Therefore, we advise to limit the use of release agents as much as possible or to work with mould materials that do not bond with A1.