Wednesday 25 February 2015

Calcium Silicate for Moulds

I have recently discovered calcium silicate board. It is light weight, with no fibrous material. It is workable with wood carving tools and can be smoothed with sanding papers. It is manufactured in 25 mm thick boards, and so is suitable for shallow forms.



It requires no hardeners, but it does require kiln wash to ensure clean separation of the fired glass. It also is durable, but needs careful storage and handling.  It does not appear to warp with repeated heating.

High performance calcium silicate board will withstand temperatures of 870C for limited periods, according to the manufacturers.  It is best to support the shelf well and consider it a mould or shelf for temperatures at or below full fusing where it is known to perform very well.

An additonal factor in its favour is that it is significantly cheaper than either ceramic fibre board or vermiculite board.

2 comments:

  1. Do you have a recommended firing schedule to pre fire or fire with this product. Is it likely to crack at thicknesses of 52mm. And do you know from experience how many times it can be reused in the kiln for fusing temperatures?

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    1. I find that calcium silicate is useable at fusing temperatures for a few times. It is not a permanent mould material. It does need to have a separator, although it does not need to be fired before use. I have no experience of the 52mm board, although it is likely to perform as the 25mm board does.

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