Cottle boards

[kevinpleong]

I am new to mold making and purchased two pure and simple pottery plastic master molds. I would like to make some molds for slip casting and not just molds for handbuilding. I was wondering how to make cottles for slip casting. What sizes should I make too?

 

Thanks

[Min]

6 hours ago, kevinpleong said:

What sizes should I make too?

Depends how large the molds will be but they are adjustable to be smaller. I like using roofing flashing (for cylinder shaped molds) that comes in different lengths from a hardware store. I tape up the seam with duct tape and seal the bottom where it sits on the table with soft clay coils made from waste clay. If you cut a long piece it is also adjustable and reusable.

 

[Chilly]

On 7/4/2022 at 5:17 PM, kevinpleong said:

What sizes should I make

I have boards made as in that video above.

First you need a base board.  Then decide what the tallest size you will need.  Then make the length of the boards so you can clamp them and they still fit on your base board.

I've also used cardboard boxes, fruit boxes, tupperware containers, anything that will hold the weight of the plaster, or can be lined with bin bags and padded out with cardboard, foam, anything.  Usually I'm restricted by height more than any other dimension.

[PeterH]

Just to emphasise that the "height" of your final mould can more than the "height" of your cottle boards. Not least because it may be easier to create multi-part moulds this way.