RTV Tray Warpage and Curl, Oven or Fridge | RUUIPON

A custom RTV tray that cups, potato-chips, or won't sit on the pan is usually a support problem that heat or cold made obvious. Oven batter on an unsupported sheet cooks the top face faster than the pan side, so the tray curls. Fridge or freezer storage stacked wet "sets" a curl that then dumps outer-row gummies heavy. A missing jacket, a sheet that is too thin for the span, or a bake hotter than the RFQ all look like "bad silicone" from the packing table. Sit the empty tray on a known-flat plate at room temperature before you ask for a harder Shore.

RUUIPON pours platinum food trays and craft skins in Bao'an since 2018. Compression-molded HCR bakeware *parts* or LSR kitchenware are wydsilicone.com — different shrink (HCR often ~1.5–2.5%, LSR ~2–3%), different tool.

Does not apply when the warp is a steel mold plate, when you baked a 20A gummy sheet as if it were a cake pan, or when ISO 3302-1 M2 on the drawing is being used as a flatness spec it isn't. Rubber class is not a tray-flatness callout.

Heat curl vs cold curl vs storage stack

Cups in the oven, sits flat cold on the bench. Cause: thermal gradient plus a floppy span. Edges lift; center stays on the pan. Confirm: empty tray on a granite plate at room temp vs after a documented bake. If it only cups hot, you need a jacket, a pan, or a firmer food tray Shore (often 35A–45A for baking sheets — don't copy that onto a gummy dump). Fix: spec a support pan or mother mold; don't chase Shore alone. Tell us peak oven temperature on the RFQ.

Potato-chip twist that stays after cool-down. Cause: baked far above what the RFQ assumed, uneven oven, or a tray pulled and racked while still floppy-hot. Confirm: oven setpoint vs a probe on the pan. A twist that will not relax at room temp may be a set deformation — recast with a jacket, and write a racking rule. Fix: we recast; we also write "cool on a flat pan." We would not recommend hanging a hot sheet on a round rack.

Curl only after fridge or freezer, cavities facing in, nested. Cause: cold set in a stacked banana shape, often with water in the nest. Confirm: one tray stored flat and dry vs the nested stack. Fix: store cavity-up, dry, unstacked or with a flat separator. Recast only if a hinge nick formed.

Outer row of a gummy dump is 3–6% heavy and the sheet looks "smiling." Cause: loaded-tray edge sag 0.5–1.5 mm — cousin of warp, same missing jacket. Confirm: weights on a supported pan vs on the bench. Fix: jacket or fewer cavities. See the gummy demold article for the tear version of this.

One corner up, always the same corner, even on a new unused spare. Cause: poured against a master or box that wasn't level, or a jacket that was pulled early. Confirm: spare from the same PO does the same corner. Fix: remake on a checked box. That's on us if we poured it. Send the spare photo on a granite plate with a feeler or a coin stack at the high corner.

Jacket keys that actually keep a sheet flat

A mother mold or a simple aluminum pan only helps if the RTV skin locates on it the same way every bake or dump. Keys that are too shallow let the sheet walk; a jacket pulled before the platinum has finished will lock a twist you then call warp. On a gummy dump, that twist is also the 0.5–1.5 mm edge sag that makes outer-row pieces 3–6% heavy.

We check the pour box is level, then we want your first cycle photo on a known-flat plate — empty, room temp — before you send a hot-from-oven shot. If the spare is already high-corner on granite, that is our box, not your oven. If the spare is flat and the worker cups only hot or only after a wet nest, we spec support and storage rather than a new Shore.

CAD lock (simple 3D USD $50 when that scope applies) → platinum pour 1:1 or 10:1, vacuum → jacket if the span needs it → prototype commonly 3–7 business days after CAD lock → you run one bake or one fridge rest → send the plate photo. Production stays MOQ 20 pieces per design after that photo, not before.

Typical shop values

Caption: Typical shop values.

The photo that would prove it: tray on a known-flat plate, backlit gap at the edge, tape measure on the span, "hot from oven" vs "room temp spare" labeled. No lifestyle bake shot.

Worked example (anonymized)

A seasonal cookie tray, platinum ~40A, 400 mm span, no pan spec. First bake at a shop oven that ran hotter than the home recipe. Corners lifted; brand logo browned on the high edge. We asked for a bake on an aluminum sheet. Cup dropped. Recast added a light jacket and a written "stay on pan until cool." Shore unchanged. CAD already locked.

One procurement mix-up

"Oven-safe silicone" copied from a consumer muffin cup is not a span, a Shore, or a pan rule. Write peak °C, tray envelope, and whether a sheet pan is allowed. Tooling charge ≠ unrestricted ownership of a recast after you hung hot trays over a sink.

We would not recommend

We would not recommend baking a gummy dump sheet.

We would not recommend freezer-stacking wet trays.

We would not recommend raising Shore to flatten a 400 mm span without a jacket or pan.

We would not recommend quoting HCR bakeware as an RTV tray.

flowchart LR
  A[Tray not flat] --> B{Room-temp on a granite plate?}
  B -->|Already high-corner| C[Pour/box/jacket — remake]
  B -->|Flat cold| D{Cups only in oven?}
  D -->|Yes| E[Pan + jacket; write peak °C]
  D -->|No| F{Curl after fridge nest?}
  F -->|Yes| G[Store dry, unstacked, cavity-up]
  F -->|Smiling under load| H[Jacket; outer-row 3–6% is sag]
  E --> I[Do not hang hot sheets]
  G --> J[Recast only if a nick set the curl]

What to ask when you're buying

• Peak oven or freezer temperature, not "kitchen use"?
• Tray L × W and whether a sheet pan is mandatory?
• Jacket / mother mold allowed on the line?
• Storage: nested wet or flat dry?
• Food path 177.2600 / LFGB as article tests.
• ISO 3302-1 class if any — still not a flatness spec.

RFQ copy-pack

[email protected] · +86 135 3006 2969

RUUIPON warp / curl RFQ Photo on a flat plate, backlit gap: When it cups: oven / fridge / always / under load Peak temp °C: Span mm: Jacket or pan allowed? Pour: batter / pectin / other Qty: prototype / MOQ 20 CAD: STEP / $50 3D if we add ribs Docs: 177.2600 / LFGB / none

Matched next step: send the granite-plate photo and the temperature. We add a jacket or recast the span. We will not start by selling 60A. Prototype 3–7 business days after CAD lock. MOQ 20 per design.

Related: custom silicone baking molds, custom silicone ice molds, custom silicone gummy molds, contact.

FAQ

Will a harder Shore stop oven curl? Sometimes on a small muffin cup. On a wide sheet, Shore without a pan or jacket still cups. Spec support first.

Can I freeze gummy trays nested to save space? You'll train a curl and a wet face. Store dry and flat. Nested wet storage is a common outer-row surprise.

Is platinum shrink why my tray warped in the oven? Unlikely. Platinum RTV linear shrink is about 0.1–0.3% at cure, not a bake potato-chip. Look at span and temperature.

Do you flatness-inspect every tray? We check the pour box and a sample on a plate. Your first bake or fridge cycle is still the real test — send that photo if it fails.

If you add a jacket, is that still MOQ 20? Yes, 20 pieces per design after you approve the jacketed witness. $50 3D only if we must remodel ribs or span in CAD.