Adding Thixo to Brush-On Platinum RTV Coats | RUUIPON

A thixotropic additive is how you keep platinum RTV on a vertical master instead of in a puddle at the base. You mix A/B 1:1 or 10:1 by weight first, then fold in the named thixo until a stipple holds on a test coupon — usually a small percent by weight, grade-dependent, never a "squeeze until it looks like frosting" cup mark. Too little and the detail coat slumps off serifs. Too much and the coat won't wet a 0.3 mm logo, traps brush air, and cures as a cratered orange peel. Thixo is a sequence tool for a glove, not a cheaper drum and not a food-cavity grease.

RUUIPON builds brush-on and pour-on platinum tools in Bao'an since 2018. Prototype 3–7 business days after CAD lock. MOQ 20 pieces per design. USD $50 when CAD scope applies. [email protected] · +86 135 3006 2969. LSR *parts*: wydsilicone.com.

Does not apply when the master already sits in a leak-tight flask and a vacuum pour will bury it — don't thixo a box pour "for luck." It also does not apply to caulk-tube acetoxy skins, to thickening food dump (pectin, chocolate), or to painting thixo onto a finished food well as release. Food cavities stay dry. Steel HCR/LSR tools are recut, not brushed.

Dose on a coupon before you touch the master

Thixo changes yield stress. The mix should hang on a vertical 50 mm coupon for the pot-life window without a drip bead at the bottom edge, and still wet a 0.5 mm engraved line on that coupon. We mix a 20–30 g slug, add thixo in small increments, and only then scale to the glove. Copying last month's "two squirts" fails when the room is hotter and pot life is shorter.

Typical failure modes:

• Slump on verticals, puddle at the flange. Under-dosed, or the first coat was applied after the mix started to gel. Recoat while the previous skin is still tacky enough to knit, or you'll delaminate.
• Starved serifs, white peaks, brush marks that print. Over-dosed, or you dry-brushed instead of stippling into the texture. Thin the next coat or switch that master to a pour-on box.
• Cratered face after cure. Air whipped in with the thixo. Fold, don't beat. A brush coat does not replace vacuum on the *unthixed* A/B if the grade allows a short vacuum before you add thixo — follow the TDS; some thixos hate vacuum.

We would not recommend adding household fumed silica from a hardware bag "as thixo." Unnamed filler can inhibit platinum, shift Shore, and void a food path.

When a pour-on box still wins

Brush-on plus thixo wins when the master is vertical, already wall-mounted, or so tall that a box would waste kilograms of gum. Pour-on wins on a tray, a bar, a small boxed figurine: uniform Shore, keys poured in, less labor. On a 40 mm resin badge, thixo plus three coats plus a jacket often costs more than a vacuum box pour of the same platinum.

Run the RUUIPON Mold Structure Decision before you open the thixo: flat back → open-back / tray pour. Else deep undercuts that will not peel → two-part / plug / core. Large wet dump → mother mold. Thixo does not replace a jacket. A 10A–20A hanging glove still balloons under wet plaster unless a mother sits behind it.

Coat thickness is a different spec (detail coat millimetres). This page is the additive that lets that coat hang. Don't conflate them on the RFQ.

flowchart TD
  A[Master on the bench] --> B{Will it sit in a leak-tight box?}
  B -->|yes| C[Pour-on after vacuum — skip thixo]
  B -->|no vertical or huge| D[Mix A/B, coupon-dose thixo]
  D --> E{Coupon hangs and wets 0.5 mm line?}
  E -->|no slump| F[Add thixo, retest]
  E -->|no won't wet| G[Reduce thixo or change sequence]
  E -->|yes| H[Stipple detail coat, then body coats]
  H --> I[Jacket the glove]
  C --> J[Witness dump]
  I --> J

The photo that would prove dose: a vertical coupon with a held stipple and a wet 0.5 mm line, next to a slumped coupon from the under-dose, coin for scale. A glossy catalog glove with no coat lines does not prove thixo was used.

Typical shop values

Caption: Typical shop values.

Worked example (anonymized)

Architectural panel, 600 mm tall relief, platinum ~15A glove. Buyer asked to "just pour it thicker so we don't need thixo." A box that tall would have wasted several kilograms around the void. We coupon-dosed thixo, stippled a detail coat into the lettering, two body coats, plaster-bandage mother in the shop (the panel does not ship wet). CAD already locked from a scan — no $50 3D. Witness peel, then MOQ 20 skins on a rotation. Food was never on this PO.

One procurement mix-up

"Brush-on kit" on a marketplace listing is not a production thixo spec. Some kits are tin, some are already thixed, some are pourable with a separate packet. Write platinum vs tin, whether we dose thixo here, and whether the dump is food. Tooling charge is not unrestricted ownership of a recast if you later switch to a pour-on and expect the same grams.

We would not recommend

We would not recommend thickening a food-cavity pour with thixo so you can skip a mold box.

We would not recommend hardware-store fumed silica as a platinum additive.

We would not recommend a single thixed coat as a production mold for weekly PU. Add body coats and a jacket.

We would not recommend brushing thixo onto a chocolate well as release. Food cavities: no grease, no tin.

What to ask when you're buying

• Pour-on box or brush-on glove for this master envelope?
• If brush-on, who doses thixo, and do we see a coupon before the master?
• Jacket material: plaster, FRP, or printed shell?
• Food or craft dump — cabinets stay split?
• Who keeps the master after the glove is approved?

RFQ copy-pack

Send to [email protected] · +86 135 3006 2969 · Xinhe Blvd, Shajing, Bao'an.

RUUIPON thixo / brush-on RFQ Master envelope mm; vertical? yes / no Can it sit in a leak-tight box? yes / no Dump: PU / epoxy / plaster / food (food = no thixo-as-release) Shore target band: 10A–20A glove / other Jacket: plaster bandage / FRP / printed / undecided Thixo: we dose here / buyer kit named Qty: coupon + witness / MOQ 20 CAD: locked / $50 3D if scan still open

Matched next step: send the master envelope and whether a box is even possible. We coupon-dose thixo on gloves. We will not thixo a chocolate pour. Prototype 3–7 business days after CAD lock. MOQ 20 per design.

Related: pour-on vs brush-on, glove vs block, when you need a mother mold, contact.

FAQ

Can I add thixo to a 1:1 mix by volume in a marked cup? No. Mix A/B by weight, then dose thixo by weight from a coupon. Cup marks on a thixed mix are how you starve a logo.

Does thixo make tin leftover smell less? No. Thixo is rheology. Tin odor is condensation chemistry. Food cavities we quote stay platinum and ungreased.

Will extra thixo let me skip the jacket on a wet plaster dump? No. Yield stress is not hydrostatic stiffness. A hanging 15A glove still wants a mother under wet kilograms.

Can thixo hide inhibition on an SLA master? No. Inhibition is chemistry. Seal or post-cure the print first. A thicker hanging coat still cures sticky against sulfur or uncured resin.

If the coupon slumps, do I still pay the $50 CAD? CAD fee applies when geometry is still open. A slump is a mix issue. We re-dose the coupon; we don't remodel the relief unless the peel still fails after the coat hangs.