What’s a good mold wall thickness?

[Mitzuuu89]

My molds are round shaped, with a wall thickness of about 3-4 cm.

it’s ok for smaller molds, but for large ones they’re quite heavy.

i’ve noticed after slip casting that water builds a round layer of about 1-1.5cm

 

what’s a recommended wall thickness for slip casting molds?

[Chilly]

I think most books I've read on the subject say 2 inches.

Yes, as they get bigger they get heavier.  Also as they get bigger, the water to plaster ratio increases, so the moulds need to be even thicker.

[Mitzuuu89]

Just now, Chilly said:

I think most books I've read on the subject say 2 inches.

Yes, as they get bigger they get heavier.  Also as they get bigger, the water to plaster ratio increases, so the moulds need to be even thicker.

hmm that's interesting, I would expect the wall thickness to depend on the desired ceramic wall thickness, no matter the size of the mold

[Mark C.]

The bigger the form the thicker the walls need to be to absorb the water.so what size  of the form are we talking about???

I used to slip thousands of 5 inch tall aroma therapy lamps the molds where about1.5 inches  to 2 thick in all directions.

[Mitzuuu89]

2 hours ago, Mark C. said:

The bigger the form the thicker the walls need to be to absorb the water.so what size  of the form are we talking about???

I used to slip thousands of 5 inch tall aroma therapy lamps the molds where about1.5 inches  to 2 thick in all directions.

Forms are about 18 cm x 14 cm. And the walls need to be 1cm width

[Chilly]

I've never cast anything that thick.  My head says, the thicker the cast, the thicker the mould need to be, in order to absorb even more water from the slip.  But, my head also says, will the water travel through that much "drying" slip?

[Terrance]

I have been told the best thickness for casting is one inch, all around.  The mold dries faster when the thickness is one inch.  1.5 to two inches takes longer.   When I use my silicon rubber bat maker I can go to 2 inches.