In today’s video, we will make a press mould using raw clay.
First, we made a design using some firm paper and then moulded the soft clay to our desired design. Once it has dried enough to hold its shape, we then fill the design with rice to help maintain its form when under pressure from the plaster (thanks to @alison.skate.pots for the idea)
We then attach a back to hold the rice in place (remember to score and slip), then attach a larger piece of clay to that backing we just added to press it onto the inside of the container we will pour the plaster into.
We then measure out our materials In a 70% water-to-plaster ratio. We then mix the material by sifting the plaster through our hands and letting it sit for a few minutes (I usually leave it for 1-2 min) until the water has soaked into the plaster; then we mix with a high-speed drill.
Once thoroughly mixed, we pour the plaster into another bucket and mix again. We then spray the container and design with a Windex solution to fight air bubbles (1:3 Windex to water). You now pour the plaster slowly into the container. Be sure to let the plaster flow over the design as opposed to pouring straight on the piece.
This is part 2 of this video on making a new press mould; in part 2, we will make a silicone mould of the plaster mould.
The first step is to make a mould box using some wood to make a box shape and hot glue it to some stiff masonite to create an area for the silicone to pour into (and not pour out everywhere).
Once that is done, you prepare the mould and the box with three coats of mould soap. You can then hot glue a small amount In each corner of the mould and attach it to the mould box base to stop it possibly floating away when you pour the silicone into the mould box. As and extra precaution I also put some masking tape around all the joints of the mould box to make sure that the silicone cannot get out.
Next, you weigh out your materials; for me, it was a 2 part cure. From memory, it was 5kg of silicone and 500 grams of catalyst.
Once you have weighed out your materials, you can begin mixing them with a drill while avoiding adding additional bubbles. (Mind you, I have silicone that has a pot life of 120 minutes, so if you like not to rush when you are working, then get a longer pot life; however, it will increase its hardening time).
Once you thoroughly mix the two substances, you will need to get a tall ladder to stand on over the mould. (Or anywhere where you can create a long stream from your bucket to the mould box)
Place the ladder next to the mould box, get on the ladder and have someone hand you the bucket and pour your silicone into the mould box slowly and in a small stream to help burst the air bubbles trapped in the silicone.
Once it is filled to the top, you are nearly finished. All you need to do is keep an eye on the mould box to ensure there are no leaks.
Thanks for watching hope you enjoy this video and check out page for more helpful pottery tips and have a Merry Christmas
