I love making concrete art. The problem is, that in order to make my own moulds, I need to use liquid latex, which doesn’t smell to good ; )
I start with my original, and apply a layer of liquid latex using a paint brush. The latex takes approx. an hour to dry on a warm day. I keep repeating this painting of latex layers, until the colour has changed from a white colour to a yellow/brown colour – about 20 layers.
I lie the latexed gnome so he’s level, on a rolled towel and press a thick line of clay around the edge of the gnome, dividing him in half. I oil the layex so that the plaster of paris mother mould comes away from the latex once dry.
I sieve the plaster of paris with water, enough the make a slurry. I use a spatula to spread the plaster all over the first half of the gnome. I find it easier to use my hands, to pat it down, making sure it is in every nook.
Once the first side has dried, I flip the gnome, and remove the clay guide. I rub Vaseline along the plaster edge, so the next side of the mother mould will not join the first.
Repeat the application of plaster to form the second side to the mother mould.
When the two sides are dry they can be separated from the latex mould. I use a blunt knife to wedge between the two halves. If the mother mould happens to break don’t worry, because the pieces can be held together using a bandage ; )
I use towels to help stabilise the mould in a bucket, ready for the concrete pour.
I use a mixture of 1:2 Portland cement : Washed Builders Sand and enough water to make a nice slurry. I glove up and use my hands to mix the concrete, getting rid of any lumps. After pouring, I shake and jiggle the bucket, trying to get rid of the bubbles within the casting. Spraying the mould with oil prior to casting can help reduce bubbles, and aid in removing the cast from the mould once set.
I get my liquid latex from http://www.triginstruments.co.nz