Designing Complex Textures and Logos Inside Custom Silicone Tool Cavities

A logo that fills and a texture that tears are opposite cavity problems. Treat them as two drawings.

Complex consumer and industrial silicone loves grain, icons, and raised type. LSR will copy a fingerprint. That is not the same as surviving demold, holding a serif through tool life, or filling a 0.2 mm valley at the end of a flow path. RTV will copy an SLA print’s voxels and call them texture. Steel will chip a standing serif and call it wear.

This is cavity-side design for LSR/HCR steel first, then what changes in RTV.

Raised vs recessed on the part (the mapping people flip)

Decide on the part, then translate.

LSR’s low viscosity makes fill of fine female detail easier than in HCR. It does not make strip of a deep male grain free. Texture draft is not optional because the rubber is soft. Light grain often wants about 3°; medium grain 5°+ (same order as common plastic texture DFM, and for the same drag reason). Smooth LSR walls can live at 0.5-1°. Do not mix those on one face without a boundary.

If you ignore this: a leather grain at 0° on a 40 mm-deep grip scores on every shot. You then “polish the texture off” in maintenance and the parts go glossy in patches.

Logos: depth, stroke, and draft

Write numbers on the art, not “crisp.”

• Stroke width vs depth. A deep, skinny trench (raised on the part = female in steel) does not pack, especially in HCR and at the end of flow. A standing hairline (recessed on the part) chips.
• Sidewall draft on letters: 1-3° is a working band in steel; more if the letter is deep. 0° letters are EDM jewelry, not production.
• Fillets at the floor and crest. True sharp is a wear spec. A 0.05-0.1 mm crest radius on standing type is often invisible in silicone and doubles tool life.
• Serifs and micro holes (e, a, 8). These are the first to fill with flash or to break. Simplify the typeface for molding, or go larger, or recut inserts as a planned spare.
• Location vs gate. Fine female logos opposite a late-fill zone come out rounded. Put critical art near fill, or accept a flow study.
• Parting line through letters is how you get a step in the brand. Park the split on a border or outside the island.

RTV logos copy the master. Finish the master (SLA article in this cluster). Do not expect a poured 10A mold to hold a 0.15 mm serif for a production year. Recut art in steel if the logo is the product.

Textures that lock the part

Grain depth is extra undercut, thousands of times.

Rules that belong on the texture callout:

• Name a standard (VDI, Mold-Tech, SPI, a plaque ID). “Soft leather” is not a cavity.
• Add draft for that depth.
• Keep grain off shut-offs and seal lands unless you want a leak path or a crushed grain.
• Fade or border the grain so it does not run off a parting line and flash into a fuzzy edge.
• For grippy consumer parts, a shallower grain you can actually strip beats a deep grain you tear and then polish away.
• In RTV, FDM or voxel noise is a texture whether you specified one or not. Sand or you own it.

If you ignore this: the first 200 shots look rich. Shot 201 shows a dull stripe where the operator started using more force, then more release, then a scraper.

Artwork files the toolroom can use

Send:

• Vector logos (AI/SVG/DXF) at 1:1, outlined fonts, revision in the filename
• Depth, draft, raised vs recessed on the part
• Position on the 2D with a datum that exists on rubber
• Texture plaque or standard + area plot
• Which faces are polish, which are grain, which are “no texture within X mm of seal”

Do not send:

• A PNG from marketing
• A screenshot of a Blender displacement
• “Match this competitor photo”
• CAD with a bitmap wrapped on a surface and no depth

CAM will need a real surface or a chemical/laser/EDM texture process. You do not need to name a software button. You need a surface the process can hit. Undercut grain in a pocket the cutter or the etch cannot see will come back as “simplified.”

Laser and chemical textures on steel are production methods. Etching an RTV mold with a kitchen acid is not. For RTV, texture the master (printed, engraved, or a textured sheet) and copy it.

First-article coupon, not a philosophical grain

Cut or pour a texture/logo coupon in the real compound: the actual depth, draft, and hardness, stripped the way production will strip. Photograph it next to the plaque. Check fill at the serifs, drag marks parallel to pull, and whether the grain still reads after the planned post-cure (some shrink slightly muddies fine pits).

Pass that coupon before you texture eight cavities. Recutting one insert is DFM. Recutting eight because the screenshot lied is a second tool.

RFQ line: *Logo [raised/recessed on part], depth, draft, vector file rev; texture [standard], depth, draft, keep-out on seals; process LSR/HCR/RTV.* If that line is “add some grip,” the cavity will get whatever was on the last job.

FAQ

Should a logo be raised or recessed on the silicone part?

Decide on the part, then translate. Recessed art is standing type in steel and chips; raised art is a female sink that can short or trap gas. LSR fills fine female detail better than HCR; it does not make a deep male grain free to strip.

Why extra draft on grain if LSR is soft?

Texture depth is extra undercut, thousands of times. Light grain often wants about 3 degrees, medium grain more, for the same drag reason as plastic texture DFM. Smooth LSR walls can live at a fraction of a degree. Leather grain at zero draft on a deep grip scores every shot until someone polishes the texture off.

Can the toolroom mill from a marketing PNG?

No. Send vector art at 1:1 with outlined fonts, depth, draft, raised versus recessed on the part, and a datum that exists on rubber. Bitmaps, competitor photos, and wrapped displacements come back as simplified or as whatever was on the last job.

Will a poured 10A RTV mold hold a hairline serif for a production year?

Do not count on it. RTV copies the master, including voxels if you printed one. Recut brand-critical art in steel, or finish the master and accept that a soft mold is a short-run copy.

Why cut a texture coupon before texturing eight cavities?

You need the real depth, draft, hardness, and strip path, photographed next to the plaque, including after post-cure that can muddy fine pits. Recutting one insert is DFM. Recutting eight because a screenshot lied is a second tool.