Plaster of paris & flexible moulds

After seeing pro’s making sand castles and learning about the Pound-up process. I thought it would be good to use the same process to cast my concrete product. I stumbled across a picture of a guy using a vinyl sheet to build sand up vertically. I have never found that image again. And I cant find anything else on the net where they use this vinyl sheet. Although you can’t make any undercuts… I think it’s still the best way to achieve complex curves with concrete. Because it’s a liquid, you’re normally limited to the shape of your mould because of gravity. So why not turn the mould on its side and pour it in from the top. The rebar can still be placed in the centre of the mould. Once the concrete dries you can remove the mould and flip the finished product on its feet.

I had some plaster of paris and some aluminium left over from my previous models. I couldn’t help myself. I had to try it out.

This shape comes from a clay model I made a few weeks ago- the shape was modified by a skater (see skate participant #1 blog post).

Aluminium mould

Aluminium mould- mock up

clay was used to seal the bottom of the mould

clay was used to seal the bottom of the mould

Note to self…Clay will not seal the bottom of the mould! Next time use gladwrap and sitcky tape.

Pouring Plaster of paris in to the mould

Pouring Plaster of paris in to the mould

Here is a clip I found on youtube that uses a flexible mould. Its interesting to see what is possible with a liquid material. Notice the foam-like flexilbe mould being used on a horizontal surface. Non-stick!


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One Response to “Plaster of paris & flexible moulds”

  1. Haley Says:

    Is it still drying? I hoped it worked somewhat, can you sand plaster afterward to shape it if the plaster came out of the bottom slightly where the clay was?

    It’s good to see what you have been up to all the other blogs in the class have been very quiet and I love checking how every one is going as you get inspired, and full of ideas hope you don’t mind me leaving comments, but I find it helpful in my process to get feedback. 🙂

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