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Slip Casting Large Forms


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I'm in the process of planning a very large slip cast mold. The dimensions of the final piece is aprox 16-20" in one direction. I'm also estimating the mold will hold 5-7 gallons of slip...But there's a twist...


This is not a traditional slip cast I'm attempting. It's a much larger version of the "series of two part molds" in this video:


The reason I'm doing this is because I want each casting to be slightly different (rotate the layers, move them around, put them in different orders, etc.)


My questions before I attempt this are:


Do you think this can be done? Is the weight of the slip too much to hold in?

Do you have any suggestions for attempting this?

Have you done something similar before? What were your challenges?


Please help! I've already invested time in a small scale model and it works perfectly... but, I need all the help I can get on this one because it HAS to work one way or another or I'm in deep do-do (time-wise). Any input would be GREATLY appreciated! Thanks!


I've also attached pictures of the test mold I made and the first casting. You can see that the casting is very rough... this was because the slip was very thick for a small mold and I opened it up too soon because I was so damn excited to see if it worked or not. Once the mold dried I poured another one and it came out perfect.


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Yes it most likely can be done-The biggest issue will be the joints or seems leaking in the stack of plaster forms-

you could as mentioned in the video you posted mix the slip thicker which will help

You will have trouble flipping this mess keeping it all together to drain so i suggest siphoning or pumping the slip back out-which may help

You can plug any leaks on those forms with clay when you are pouring it.

It can be done-this is how you will learn how by trying


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I think the design is possible and rather simple to construct with 'a little' precision. I see a few things in the YouTube video that may pose a few problems with this multi-piece mold. There were no vertical bands to hold the molds together and there was no spare for pouring the slip out. But first (if you haven't done so already) is to sketch out the entire design then deconstruct it, considering the mold designs and the necessary components.


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I, like Lucille, had noticed no vertical bands which I would consider equally as important as your horizontal.


An easy binding tool one could make (illustrated below) from 1/2" (minimum---thicker would probably be better)

plywood would be as illustrated. Since you are working with the same forms (in thickness- relatively even thickened

pieces I would assume), it would be easy to measure the thickest total height and cut these interior dimensions of

the plywood with a little extra play or 'wiggle' room. A number of thin wood (not plywood) shims, some flat, some

possibly with a little wedging angle would suffice to bind the form solidly together. I would imagine three or four of

these around the exterior of your form should suffice, dependent upon how and where the horizontal parts are

positioned with their 'rubber bands'.

Just a thought.... wink.gif I like the potential in your project. Thumbs up!





P.S.... Yeah bellonart, the massive sized pictures you have linked were a bit hard to see at one time without manually moving the picture around the monitor. If you use unedited pictures straight from a camera (millions of MB) it generally looks this way. If you use a program like Photoshop, or the free Open Source software GIMP to edit the size down to 600 x 800 or thereabouts it always reads much better.



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