3d printing slip mold question

[KID-IN-CLAY]

So i wanted to give a shot to 3d printing a key to make a slip casting mold. its been a wild ride learning everything and while its been really fun and interesting one question has been wrapping around my mind without any real answer too. what is an appropriate thickness a plaster mold must be to work properly? in this particualr case ive been using a unique ceramic mug i sculpted via blender.  the idea was to make a unique shape that is a particualr size that i would be able to cast multiple mugs that is also not very detailed but also unique enoghe to make it very difficult to make with the wheel. any advice or suggetions is appreached

[High Bridge Pottery]

I go with 2-3cm, I feel like anything thicker than that is too much but I can't remember if I read that somewhere or made it up.

[PeterH]

5 hours ago, KID-IN-CLAY said:

what is an appropriate thickness a plaster mold must be to work properly? i

I suspect that the wall thickness of the intended casting is-- more or less -- the absolute minimal thickness of the mould walls. (In order to absorb the water from the slip to form the walls.)

The mould also needs to be strong enough handle the weight of the slip needed to fill it, and the handling involved during casting -- perhaps requiring thicker walls  Sometimes some extra plaster makes the mould tidier/easier to cast, handle or store.

@High Bridge Pottery's 2-3cm sounds typical for few moulds I have made.

You may find this thread of interest.

Note the concerns about the texture 3D printing can produce.

[Min]

2-3 cm is pretty thin, I’ld go more like 4-5cm. (1.5 - 2”)

[Chilly]

I'm with @Min on this .  I read the question and 25mm popped into my head, then read the answers above.

But, looking at some commercial moulds, the larger the piece, the thicker the walls are.

Page 33 of "The Clay Lover's Guide to Making Molds" says:

"For most small and medium sized molds............. tocover the model by 1" (25mm)."

 

Without re-reading the whole book, I can't find any reference to thickness for large moulds, but, relatively speaking plaster is cheap, so I'd say  maximum of 50mm.

 

[PeterH]

On 8/17/2024 at 7:56 AM, KID-IN-CLAY said:

what is an appropriate thickness a plaster mold must be to work properly?

Should have said that a very thin mould will definitely need to be dried out before making another casting. A thicker mould may allow you to make multiple castings before having to dry it out.

[PeterH]

Looked up my favorite book on casting. The only thickness reference that I could find quickly was that cottle-boards should 1.5" from the nearest point of the master.

The book's cover reminded me that you need to have room for any natches.

Nice book, but not cheap.
https://www.bookfinder.com/search/?full=on&ac=sl&st=sl&ref=bf_s2_a1_t1_1&qi=xMl.V.Jx,EhL0xQKd7,WfD3S9,E_1723980007_1:7148:15334

[Pres]

You have to remember that the thickness of the mold has two purposes, Stability/strength  of the mold and absorption of water to firm up the slip.

 

 

best,

Pres

[Mark C.]

There is a new mold book out now thru ceramic arts network on mold makeing by Johnathan Kaplan. Its called Mold -Making manual

[PeterH]

58 minutes ago, Mark C. said:

There is a new mold book out now thru ceramic arts network on mold makeing by Johnathan Kaplan. Its called Mold -Making manual

Flier and sample pages at
https://mycan.ceramicartsnetwork.org/s/product-details?id=a1BUe0000004qxhMAA

[Jeff Longtin]

In my early days of mold making there were only a few books about the process. (And they were written by guys who referred to molds as "moulds". ) They tended to have a commercial orientation. I may have found the book Peter references because 1.5" has been my standard thickness since that time. 

Of late I have found 1.25" to work well, as well.  Any thinner than 1.25" and the mold can saturate quickly. Thicker than 1.5" tends to be overkill in my experience. (Unless you plan on casting twice a day, five days a week, 1.5 is sufficient.)

Jonathan Kaplan and I used to discuss mold making process on Clayart. If he's written a book about mold making I'm sure it's a good one. For many years he was the technical advisor for Ceramics Monthly. Pierce Clayton, a former mold maker in Minneapolis, also wrote a book about mold making that lots of people like.