Here’s my setup for pouring plaster in the kitchen!

Because of the ease of 3D printing case molds at home I can now pour plaster in them also. Of course, I am not in production; this is about creating prototype molds. This technique makes it possible to be precise in the amount of plaster used, so there is almost no waste. My tools are simply a good propeller mixer, and a scale and a 3-D printer (and a cooperative wife). Here is my procedure:
-Counterbalance a plastic container.
-Fill the mold with water and pour into the plastic container to get the weight in grams (and thus cc's).
-Plug that weight into https://plaster.glazy.org, set it to use centimenters and get the USG recommended weights for plastic and water.
-Put that amount of water in the flexible plastic container and tare it.
-Dump in the plaster needed (no need to sprinkle it, I have a good mixer).
-Set the timer for 4 minutes and let it soak.
-Put it under the mixer (at an angle as shown), set the speed to create a whirlpool just shy of pulling in any air (thus avoiding adding bubbles). Mix for 4 minutes and then pour it into the molds.
-Clean the mixer blade and shaft in a container of water (and throw that away outside). Let the plaster harden in the plastic container (it breaks away cleanly later).
-Let it set overnight and use a heat gun and pliers to carefully remove the PLA from the plaster.

Related Pictures

A high-quality inexpensive studio/lab mixer is here

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For many years we have searched for a credible alternative to our Lightnin lab mixer. We found this unit on Amazon but then bought it from FristadenLab in Nevada. These are made in China but packaged, documented, shipped and supported in Nevada. This cost about $300US (a programmable one costs a little more). The first impression is how heavy the unit is. The base is 1/4" solid steel. The rods are all solid stainless 5/8". The clamp is also solid metal. The shaft is 3/8" and is held in place by a good quality chuck which enables easy release. The propeller is about 2 1/2" in diameter and screws on, it would thus be easy to 3D print other propellers and mount them on a hex nut. The locking mechanism enables mounting at an angle (important when trying to achieve the highest speed without sucking air bubbles). It plugs in via a 24v DC adapter (it has a DC stepper motor so it responds gradually to speed changes selected on the dial). On this occasion, I mixed 3500g of plaster in this 2 IMP gallon bucket (2.5 US gallon) with no problem. It runs completely silent. A propeller mixer like this is a great start to DIY glazes.

A 0.1g electronic scale - a necessity for DIY lab/studio

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Weighing things is an essential part of DIY ceramics. Examples are the batching of glaze recipes, porcelain and stoneware clay bodies, engobes, underglazes, slips, casting slips. Weighing out the kaolin, ball clay, feldspar, silica, frit, etc requires a scale. Other examples include mixing slurries or plaster batches that require a specific water:powder ratio. For 3D printing a common need is weighing the amount of water a mold will hold as a way to measure its cc volume. Scales like this offer 0.1g accuracy and can handle 6000g (older ones could only handle 2000g). This enables counterbalancing stainless or even glass containers. These scales were very expensive in the past, but not anymore.

v6 Beer Bottle Drawing

Fits standard swing top stoppers.

Available on the Downloads page

3D printed case mold for making ceramic beer bottles

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3D print this, pour in plaster to make a slip casting mold! My previous work on this project assumed a smaller 3D printer (making it necessary to print flanged PLA mold sections that clip together). But larger 3D printers are now common, making the CAD work much easier. This drawing is parametric for height, body diameter, wall and plaster thickness, and neck height (for the full bottle set body=160mm, neck=96). This uses my standard clips and embeds (upper right). Neck vertices are proportional to height, so resizing works well. The top end is filleted to permit the longest possible mold on the print bed (diagonally). The bottom inside perimeter is chamfered, strengthening the default 0.8mm side wall junction to the base (that being said, be careful when removing it from the print bed, flexing too much will cause failure here).

Doing this smaller size is for prototyping and testing. Note that casting plaster on a 3D print creates artifacts (which will appear as wood grain, lower right), later I will create a hybrid plaster/PLA or rubber case mold. This PLA mold prints quickly, it has a hollow back side, permitting easy removal with a heat gun. There is no spare, it employs a pour spout, making the mold shorter and producing a better lip.

Need a stoneware slip casting recipe? L4768E or L4768H are a good choice. A glaze recipe? How about GA6-B (or similar)? Go full DIY with this, you will never turn back.

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