BumpMesh textures in a mold: keep the detail
This guide was drafted with AI assistance.
BumpMesh adds a real, printable texture to any model in your browser. Two things can undo it on the way into a mold. Mesh reduction: mold tools simplify heavy files, and a fine texture is what gets smoothed first, so in Meshcast set Model detail to Maximum. Undercuts: a texture on a side wall locks rigid two-part molds, so cast textured walls in silicone. We measured both below.
Texture the master, not the mold
BumpMesh, the free texturing tool from CNC Kitchen, turns a grayscale image into real geometry on your model: knurling, wood grain, stone, Japandi flutes and 50-odd others, or your own image. It was built for printed parts, but it is even more useful for molds. Texture a candle, soap bar or planter once, make one mold, and every cast carries the texture, hundreds of times, without another hour of printing.
A silicone mold also copies detail finer than your printer's layer lines, so a crisp texture on the master comes out crisp in the cast. What it cannot do is bring back detail that was lost before the mold was made, and that is where most textured molds go wrong.
Set up the texture in BumpMesh
Keep the base and the pour face flat
Use BumpMesh's angle masking to leave the top and bottom faces untextured, or turn on Smooth Bottom. A candle has to stand, a soap bar has to sit flat, and the face you pour through should be clean: a textured pour face gives you a bumpy base on every cast.
Pick a depth that survives casting
0.4 to 1 mm reads well in wax, soap, resin and concrete. Deeper textures trap more air in the pour and make the mold harder to release. BumpMesh warns that a texture deeper than 10% of the model's smallest dimension can make the surface overlap itself, which a mold tool then has to repair.
Keep the resolution fine, then export 3MF
BumpMesh warns that a resolution coarser than 1/100 of the model's diagonal loses fine detail. Fine resolution means a big file: our 60 mm test cylinder came out at 755,000 triangles, a 38 MB STL. Export 3MF if you can; Meshcast reads STL, OBJ and 3MF up to 100 MB.
The upload setting that decides how sharp it stays
A mold generator does not need 755,000 triangles to cut a cavity, and pushing them through makes every step slower. So Meshcast's mold tools simplify big uploads, and in the Model detail setting you choose how far: Faster (50,000 triangles), Balanced (the default, 100,000) or Maximum (keeps up to 700,000 untouched). For a smooth model all three look the same. For a texture they do not, so we measured it.
| Texture (0.6 mm deep) | Faster | Balanced | Maximum | Not reduced |
|---|---|---|---|---|
| Fine: 1.5 mm pattern | 0.23 mm off | 0.11 mm off | 0.06 mm off | 0.05 mm |
| Coarse: 4 mm pattern | 0.02 mm off | 0.02 mm off | 0.02 mm off | 0.01 mm |
Two things stand out. It is the fineness that matters, not the depth. The coarse texture came through every setting almost untouched. The fine one came out up to 0.11 mm off on Balanced, about a fifth of its 0.6 mm depth, and up to 0.23 mm off on Faster, more than a third: its ridges round over and its valleys fill in. On Maximum it was as sharp as the file we started with.
Then upload the file again. The reduction happens once, when the file loads, and the Advanced settings only appear once a model is in. So: upload, open Advanced settings, set Model detail to Maximum, and upload the same file a second time. Meshcast remembers the choice, so from then on every upload in every mold tool keeps its detail.
Textures lock rigid molds
A rigid mold, like a 3D-printed two-part mold, opens by pulling its halves straight apart. A texture on a side wall runs across that direction, and every bump is a tiny undercut the rigid halves hook behind. We ran the same cylinder through Meshcast's mold advisor, which scores how well each mold type suits a model, out of 100:
| Cylinder, 60 mm | Surface that locks a rigid mold | Rigid two-part mold | Silicone shell |
|---|---|---|---|
| Smooth | 0% | 95 | 98 |
| Coarse knurl, 4 mm, 0.6 mm deep | 3.1% | 85 | 98 |
| Fine knurl, 1.5 mm, 0.6 mm deep | 8.0% | 40 | 98 |
A smooth pillar is a textbook rigid-mold shape. Knurl its sides and it becomes a silicone-only shape. Silicone stretches over the bumps and peels off; rigid plastic cannot. The rule of thumb:
- Texture on side walls (candle pillars, planters, vases): silicone mold.
- Texture only on a face the mold pulls straight away from (the top of a coaster, a tray, a soap bar's face): a rigid printed mold works.
- Vertical flutes and ribs sit in between: they run the right way on two sides of a two-part mold and the wrong way on the other two. Draft angles and undercuts explains why.
Pouring into a textured mold
- Brush a first coat. When you make the silicone mold, brush a thin layer of mixed silicone into the texture before you pour the rest. Air sits in every groove, and a brushed coat pushes it out.
- Degas if you can, pour slowly if you cannot. Pour a thin stream into one corner and let the silicone flow across the texture instead of landing on it.
- Release for resin and concrete. A texture multiplies the surface the cast grips. Use a release agent every time, and give concrete a vibration or a few firm taps so it fills the grooves.
- Wax fills textures well. Pour a little hotter than for a smooth mold so the wax does not skin over in the grooves before they are full.
Which Meshcast tool to use
- Silicone mold maker, box mode: the best fit for a textured master with fine detail. It prints a box around your model, you pour silicone into it, and Model detail sits at the top of its Advanced settings.
- Hugging-shell mode: a shell that follows the model's shape and uses far less silicone. It has no Model detail control of its own: it follows the choice you last made in box mode, and Balanced if you never changed it. With Balanced it suits coarse textures (a pattern of 3 to 4 mm or more) best.
- Two-part rigid mold: for texture only on a face the mold pulls away from. Its seam check shows in red where a texture would lock the halves before you print anything.
Common questions
Is BumpMesh free?
Yes. BumpMesh is a free, open-source browser tool by Stefan Hermann of CNC Kitchen. It runs locally in your browser, with no login to create, and its terms allow commercial use of what you make with it.
Why does my texture look softer after I upload it to a mold generator?
Most mold tools simplify a heavy mesh before they build the mold, and a fine texture is the first thing that simplification smooths. In Meshcast, set Model detail to Maximum in Advanced settings and upload the file again: in our test that kept a fine 1.5 mm texture as sharp as the unreduced file.
Can I put a textured model in a rigid 3D-printed mold?
Only if the texture sits on faces the mold pulls straight away from, like the top of a coaster. A texture on a side wall runs across the direction the mold opens, and every bump is a small undercut that locks rigid halves. Use a silicone mold for textured side walls.
How deep should a texture be for a mold?
Deep enough to read after casting and shallow enough not to trap air: 0.4 to 1 mm works for most candles, soap and concrete. BumpMesh itself warns that a texture deeper than 10% of the model's smallest dimension can make the surface overlap itself.
Made by meshcast.app. BumpMesh is made by CNC Kitchen; we are not affiliated, we just like it. Texture not coming through? Email us the file and we will take a look.