Custom RTV Silicone Mold Timeline: What Uses the Weeks

If you're dating a custom RTV silicone mold, the timeline is a chain of gates with queues — not a CNC-hour estimate. Steel cutting often isn't even on this job. Master finishing (especially SLA wash, UV, barrier coat), texture-house calendars, jacket work, custom dump colors, food-contact testing, and first-dump review loops are. If your PO says "mold in two weeks" without naming those gates, you've written a wish.

Process family changes the chain. A platinum RTV mold off a finished CNC master can be fast. A 24-cavity depositing tray with chemical grain on the master and an article food test cannot. Unmix them before you compare two suppliers' calendars. An 8-cavity LSR tool with a cold-runner is a different quotation for a molded *part*, not this cavity.

What actually consumes weeks

Typical time sinks, as *kinds* of work, not fake lead times:

• Unfrozen CAD and late logos. Nothing else starts honestly.
• DFM: split, keys, shrink method for the dump, CAD-safe logos.
• Master: CNC or SLA, then finish. SPI A-range on a large chocolate face is labor.
• Chemical texture on the *master* and laser queues. Subcontractors with their own calendars.
• Jacket / mother mold (plaster, resin, fiberglass, printed shell).
• RTV drums: certified food lots (FDA 21 CFR 177.2600, LFGB) vs a generic 20 Shore A.
• First-dump pack, buyer review across a time zone, correction pour.
• Dump fixtures and incoming gauges, often forgotten on the Gantt.

A shop that quotes a single number without this breakdown is hiding the queues in hope.

You can overlap work if revision control is real: dump coupons and color plaques while CAD-safe masters are cut; incoming gauges while the jacket is in layup; certificate test planning while the first pour is scheduled. You cannot overlap two CAD revisions in the mill. RTV paths parallel master finishing and jacket work. LIM paths have no master — don't copy that row onto this Gantt.

Common mix-up: "rush" as skipped master finish

A lot of RFQs treat rush as a surcharge that still ships a production platinum skin. In the shop that usually means they skipped CAD-safe logos, skipped the chip, skipped a spare skin, and sampled on a tin glove. You get a date and a mold that needs a second life as a production recast. If you must rush, label it a bridge and budget the production jacket as a second line.

China cluster shops can compress master calendar because finishers and jacket shops are nearby. They cannot compress an unfrozen drawing or a pectin that hasn't been mixed. Use the cluster for the queues it actually shortens.

Buyer-side delays belong on the same chart: logo files, legal review of food-contact claims, dump-compound lead time. Assign each gate an owner at kickoff. Peak consumer seasons fill pour tables and texture houses. A reserved slot in writing is part of the timeline. A verbal "should be free" isn't. Holidays are calendar facts; plan first-dump packs to land when engineers are at a desk, including time-zone overlap.

What to ask when you're buying

• Gate list: freeze date, master buyoff, first-dump pack due, buyer review days?
• What's on the critical path — SLA finish, texture house, food lab, or pour table?
• Production RTV and dump compound at first dump, or a written substitute?
• What does "rush" skip (CAD-safe, spare skin, full-cavity pack)?
• Who owns buyer-side logo and cert delays?

"ASAP" and "we'll try" aren't dates.

When this calendar is the wrong clock

LSR/HCR steel tools have heater and cold-runner lead times this Gantt shouldn't pretend to include. A finished physical sample poured in tin the same week can be honest if you waive recast. Geometry can override the calendar: a dirty print that needs days of finishing makes the "fast rubber mold" a detour.

Related: project workflow, sampling, cost factors.

Worked example

A 6-cavity chocolate bar, 120 × 40 mm, CNC aluminum master, platinum RTV, resin jacket, first season ~800 dumps. The long pole wasn't the pour — it was logo freeze plus a food-contact plaque slot. They overlapped the coupon of cocoa-butter shrink with master polish, flew the first-dump pack, and put lab slot + buyer review days on the PO. A "tool in two weeks" quote from another shop had omitted the lab and the jacket.

Timeline gates to paste on the PO

• Design freeze (file revision)
• Master buyoff (finish, chip, barrier coat if printed)
• First-dump pack due (contents listed)
• Buyer review period in working days
• Correction pour due if recast/recut is in scope
• SOP ready = traveler, spare skin, packing — not "first pretty dumps"
• Food-lab slot if an article test is on the critical path

Send the freeze date you'll honor, dump compound, and whether a lab test sits on the launch. We'll return a gate calendar, not a single CNC number.

We would not recommend “mold in two weeks” without naming the gates

We would not recommend a rush surcharge that ships a tin glove labeled as production platinum, or overlapping two CAD revisions in the mill. We would not hide texture-house and food-lab queues inside one CNC number. We would not start article testing after SOP if the launch needs the plaque. If you must rush, label it a bridge and budget the production jacket as a second line.

RUUIPON Mold Structure Decision: platinum off a finished CNC master can be fast. A 24-cavity depositing tray with chemical grain and an article food test cannot. Dirty print that still needs wash, UV, and barrier? the “fast rubber mold” is a detour. Hollow mandrel? pull path is on the critical path.

flowchart TD
  A[Calendar] --> B{CAD frozen?}
  B -->|no| C[Clock has not started]
  B -->|yes| D[Master finish / texture / jacket in parallel if revision control is real]
  D --> E[Pour]
  E --> F[First-dump pack + buyer review days]
  F --> G{Lab on the launch?}
  G -->|yes| H[Book the slot at first dump]
  G -->|grade letter only| I[SOP traveler]

Typical shop values

Caption these as typical shop values, not a named lot.

| Item | Typical shop value | | --- | --- | | Mix | Platinum 1:1 or 10:1 by grade; vacuum degas until the foam collapses | | Cavity Shore | 10A–20A skin with a rigid jacket | | Platinum shrink after full cure | About 0.1–0.3% — run the dump coupon in parallel with master polish | | First food tray | 6–12 cavities is a common development band | | RTV skin wall | Often 8–15 mm; jacket layup is its own queue | | Loaded-tray edge sag if the jacket is omitted to “save a week” | About 0.5–1.5 mm | | Outer-row gummy vs center if the tray sags | Edge often 3–6% heavy |

FAQ

Why do two shops quote such different RTV lead times? They're quoting different gates. One included master finish, jacket, texture, and a real first-dump pack. One included a pour hour and a handshake sample. Align the gate list, then compare. Geography matters less than the hidden queues.

Can I cut the master before dump color is approved? Yes if you accept a delta pack when pigment lands, and if shrink-critical logos are CAD-safe. No if the color load is heavy and the fit is tight. Write the waiver. Color plaques can run in parallel either way.

Should certificate testing sit on the mold Gantt? If you need an article test before launch, yes. A generic compound letter can be gathered earlier. Labs have slots. Starting the test after SOP is how launches wait on a plaque that could have been dumped at first article.

What does "rush" usually skip? CAD-safe stock, spare skins, full-cavity first dumps, and sometimes production-intent platinum. You may still need those items; you'll buy them later at a worse date. If you rush, list the skips so they're conscious.

Is a platinum RTV mold always faster than LSR steel? Often, if the master is finished and the article is actually a casting. If the master is a dirty print that needs days of finishing, or if you needed LIM *parts* all along, the "fast rubber mold" becomes a detour. Match the process to the article, then time it.