Your on-ramp to DIY glaze could be slip casting!

For any potter or hobbyist, making your own molds and slip casting presents amazing options. Making this melt fluidity tester will get you started in 3D printing, pouring plaster to make a mold and slip casting a melt fluidity tester. These will then help you understand glazes, including commercial ones, much better.

Consider how these melt flow tests demonstrate performance: Is a new brand-name material the same (e.g. tin oxide, feldspar, dolomite, Alberta slip)? Does a glaze recipe pass a sanity check? Is a batch of frit bad? Is a frit better for sourcing B₂O₃ than Gerstley Borate? Is a glaze matte because it is not melting enough? Is a glaze too reactive? Is a manufacturer's claim correct? Will a stain or metal oxide addition make my glaze melt more or less? Does a material substitute work as well as the original? How does a frit soften and melt over a range of temperatures? Do glazes of the same chemistry but different recipe really melt the same? Is this glaze prone to bubbling? Does a glaze melt have high surface tension?

Here is what you need: A geeky family member having a 3D printer, a blender, powdered slip casting clay, deflocculant, plaster and a 2000g 0.1g scale. This page is the "Next" button to get started. Everything you need to know is here.

Related Pictures

Downloadable 3D model for melt flow tester block mold

Available on the Downloads page

3D rendering of Fusion 360 drawing of glaze melt fluidity tester

This picture has its own page with more detail, click here to see it.

This is a 3D rendering of our melt fluidity tester. We have promoted this device for many years as an effective way to compare fired glaze properties (e.g. melt fluidity, surface tension, bubble retention, crystal growth, transparency, melting range, etc). Download the 3MF format file, open it in your slicer software and 3D print it. Then fill it will plaster and you have a working mold to slip cast these testers. With 0.8mm thick walls, it 3D prints quickly and is easy to remove from the plaster using a heat gun. The halves interlock using natches (requiring out embeds and related parts). The mold halves can also be lined up by the outer edges before clamping them together (thus not requiring natches).

The 3D model of a new melt flow tester mold

This picture has its own page with more detail, click here to see it.

The two pieces print as shown (top left). Since the walls are thin they may bulge a little when plaster is poured in, this is a trade-off for their light weight. The back section prints with no support, the front one needs support turned on. The file is in 3MF format, this enables including all pieces in one file (STL format does not permit that). All modern slicers can handle 3MF and they enable individually placing and orienting each piece (it is best to print them separately).

Plaster: Do not to forget to insert the clips and embeds into the holes before pouring the plaster. The mold volume is 1750cc. According to the https://plaster.glazy.org calculator, 1370g water and 1960g potters plaster are needed. You may like to mix 300:210g of plaster:water first (in a large paper cup) and pour that into the bottoms, this assures no leaking or deformation during the main pour.

Finish: Use a heat gun to peel off the PLA shell. Dry the mold and flatten the matting faces on sandpaper if needed. Then, insert the natches and spacers into the embeds. Strap the halves together, insert the pouring spout and pour in the casting slip (use a slip intended for the temperature you fire at).

Flow tester model you can 3D-print yourself

Available on the Downloads page

This picture has its own page with more detail, click here to see it.

This is not the mold, this is a model of what the mold enables you to make out of clay. Your printer should be able to make this with no support and no infill since there are no extreme overhangs (configure the slicer accordingly). This can be useful as a demonstration. It prints quickly and takes only 47g of PLA filament. It is 10% larger than fired testers will be.

Links

Articles	A Low Cost Tester of Glaze Melt Fluidity Use this novel device to compare the melt fluidity of glazes and materials. Simple physical observations of the results provide a better understanding of the fired properties of your glaze (and problems you did not see before).

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