Sandstone Mold Question

Discussion in 'Finishing Techniques' started by knurlDesign, Dec 6, 2012.

  1. knurlDesign
    knurlDesign New Member

    Pre-pologies if this is an old question. I did my best to search. I've got a large part I'd like to eventually cast in rubber/silicone.

    Because it's so big, I'm thinking of the following technique:

    1.)Print master "positive" in sandstone (for economic reasons)

    2.)Create mold of positive using traditional RTV molding techniques

    3.)Cast part in silicone.

    I fully expected destruction of the sandstone master upon de-molding which would be fine, assuming the mold is successful. I'm imagining a pretty much total disintegration at that point...just so long as it holds up until the mold cures!

    My question here is mostly whether anyone would caution against sandstone as a "positive" material for reasons other than its fragility.

    Texture-wise, I'm actually hoping for a somewhat rough surface in the casting, so to me sandstone offers that built in :)

    Any advice? Thanks in advance,


    P.S. I'm also hoping to take advantage of the 15% off deal ending tonight, so fast answers will be much appreciated.

  2. bartv
    bartv New Member
    Hi jrogers04,

    I know some artists who actually did this with FSC, although in their case they sanded and painted the positive first (it was for a bronze casting and required a smooth finish). They actually re-used the original afterwards, so if you're careful enough it may survive!