Mold Making with Philip Robbins

can anyone tell me if I can use this process over a clay (unbaked) sculpture? I'm looking to build my sculpture with clay, cast it in a flexible material, and then create an ice sculpture out of it. If it doesn't work with clay I'll carve it out of wax instead. I'd appreciate some thoughts on this!

Hello Amy,

In regards to your question about the alginate over unbaked clay, I have a few ideas for you to consider, I have used alginate over a variety of materials with much success.

I would recommend a sculpt out of Van Aken or Chavant Plastilina, This is a type of sculpting material that you can sculpt like a clay; it remains soft but it does not have a wet surface to it.

I would feel reluctant to use alginate as a casting material over a sculpture if the clay you've used is water based because the water in the alginate may remove some of the details.

As for making the ice sculpture, once you have your original sculpture casted in alginate, you've cleaned your alginate mold and poured water into it to be frozen, you will probably only get one shot at making the cast work, as alginate is somewhat fragile and tends to break in the de-moulding process. I'm also not sure how the alginate would hold up in the freezer since it has so much water in it, you may find some distortion in your mold as it freezes. This process could be done, but there is a fair amount of risk in it.

If you wish to create a mold from your sculpture that is food safe, can be re-used and will hold up in the freezer without distorting, you may wish to look at some of the silicone moulding products, or even something along the lines of Amazing Mold Putty. If you are going to the work of sculpting, it might be nice to go the extra step and make a re-usable mold, unless you are really after a quick one off.