Downloadable 3D model for melt flow tester block mold

Available as a Product on the Downloads page

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). Open the 3MF file in your slicer, move all pieces off the print bed and unselect them all. Then, print each part by moving it onto the bed and using place-on-face to orient it right. Print the funnel wide-side down with brim. Insert the natch clips and embeds into the holes, pour in the plaster, let it set and finally remove the PLA with a heat gun. You now have a working mold to make slip cast testers. Glue the natches and spacers into the embeds, strap the mold together, glue in the pour spout with slip and finish by filling the mold with slip. If the mold is dry, 10-15 minutes should be enough to get adequate thickness (don't make them too heavy). With 0.8mm thick walls, this drawing 3D prints quickly and is easy to remove when the plaster has set (using a heat gun). The halves interlock using natches (requiring our embeds and related parts). The mold halves can also be lined up by the outer edges before clamping them together (thus not requiring natches).

Available as a Product on the Downloads page

Related Pictures

The 3D model of a new melt flow tester mold

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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).

There are so many things a meld flow tester can tell you

The amazing things that a glaze melt fluidity tester can show you

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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. These will 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.

CAD drawing for 3D-printing plaster mold natches, spacers, clips and embeds

Available on the Downloads page

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Plastic natches are cast into plaster molds to provide a durable and good-fitting interlock between pieces. The traditional self-interlocking 3/8" or 9.5 mm (nipple diameter) one has not proven suitable for mold making based on 3D printing. Our solution is a four-part system.
-13.5mm holes in 3D printed case molds are all that is needed to adapt to these.
-3D printing case and block molds necessitates pouring plaster and rubber into shells with planar mating surfaces downward (they must sit flat on the table). The thin flanges on the clips cause minimal issues.
-Casting an embed into a mold enables gluing (or friction fitting) a natch or a spacer inside.
-The use of embeds permits flat mating surfaces, these can be sanded (for better flatness and fit). They also allow replacing natches if they get broken (assuming friction fit).
-A set of four interlocks (4 embeds, 4 clips, 2 spacers, 2 natches) weighs 8.7g.
Our drawing shows the measurements we use. 3D printing is precise enough that the inside dimension of the embed is the same as the outside of the natch shoulder, yet the natch fits. The same good fit happens with the clip and embed and the natch nipple and spacer (although it is necessary to chamfer the bottom corners and bevel the top corners of the spacer for better insert).
Some dimension changes may be needed to fine-tune for printing in your circumstances.

Melt fluidity of Albany Slip vs. Alberta Slip at cone 10R

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This is a GLFL test, it employs a slipcast melt flow tester to show the flow patterns of two glazes (or materials), side-by-side. Albany Slip was a pure mined silty clay that, by itself, melted to a glossy dark brown glaze at cone 10R. By itself it was a Tenmoku glaze at high temperatures. Alberta Slip is a recipe of mined clays with added refined minerals that give it a similar chemistry, firing behavior and raw physical appearance. As you can see, the melt fluidity is very similar.

Flow tester model you can 3D-print yourself

Available on the Downloads page

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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.

Melt fluidity differences are not obvious by just comparing glazed ware

The glaze on two porcelain mugs looks the same, but the melt flow is very different

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These two Plainsman M370 test mugs were fired at cone 6, the left one with G2934 matte glaze, the right one with G2934Y4 matte. They look and feel identical in the hand. The two glazes have the same chemistry. But they employ different materials to source that chemistry. The secret of of the matteness is high MgO (magnesia content). In the glaze on the left MgO is sourced by dolomite, a lot of it. The glaze on the right sources it from a special frit, Ferro 3249. The impact of this difference is visible in the melt fluidity tester, the fritted one is melting and flowing much better. On other clays, especially stonewares, the G2934 can have a dry surface that cutlery marks. Thicker applications make it worse. But the Y version exhibits no such issues. Its mattness, durability, cleanability and hardness are so good that it is being used in floor tile.

Testing a new brand of dolomite

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Dolomite is a key material for glazes, especially mattes. We were forced to adopt a new brand and needed confidence it was equivalent. Three tests were done to compare the old long-time-use material (IMASCO Sirdar) with a new one (LHoist Dolowhite). The first melt flow tester compares them in a very high dolomite cone 6 recipe formulated for this purpose; the new material runs just slightly more. The second tester is uses the G2934 cone 6 MgO matte recipe with 5% black stain; the new material runs a little less here. The third test is the high dolomite glaze on a dark burning clay to see the translucency and compare the surface character. They are very close. These three gave us the confidence to proceed.

Links

URLs	https://sketchfab.com/models/999eaa40074c4447a90e92229b7b1857?utm_source=triggered-emails&utm_medium=email&utm_campaign=model-upload#share Melt Flow Tester 3D Scan STL file at SketchFab
URLs	https://insight-live.com/insight/recipes.php?OpenFile=q6csLckZWq Download melt flow tester CAD drawing Use this model to create a multi-piece mould to make flow testers. This link enters your Insight-live account so you need to be logged in.
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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