Spare Jacket Cost for RTV Molds vs Skins | RUUIPON

A spare jacket is a priced rigid shell that still keys to the living RTV skin. It is not a free extra, and it is not "throw in four more floppy trays." Jacket cost follows size, split count, material (plaster, resin, fiberglass, printed shell), and whether the keys are CNC bosses or clay pips that will not survive a second pour. Buy the spare jacket on the same revision letter as the production skin. An unmatched shell is scrap. Recasting a torn face against an unsanded master is a different line from buying a second mother mold so you can run while the first jacket is repaired.

RUUIPON builds the skin + jacket stack in Bao'an since 2018. Prototype is 3–7 business days after CAD lock. Production is MOQ 20 pieces per design. Simple 3D is USD $50 when that CAD scope applies. Rotation of *complete* tools (skin + matching jacket) is a related but larger buy — that spare-quantity logic lives on a different page. Steel cavity inserts and LSR cold-runner drops are wydsilicone.com. Jacket anatomy: mother-mold support shell.

Does not apply when you have not locked a master yet (you need a sample, not a spare jacket), when the dump is a small dry soap that never needed a jacket, or when you want us to keep an unlabelled leftover plaster from another job as your buffer. We will not do that. Tooling charge is not unrestricted ownership of every shell in the shop.

Why the jacket is its own cost line

The RTV skin copies detail and peels. The jacket carries hydrostatic load so a Shore 10A–20A face does not balloon. Loaded-tray edge sag of about 0.5–1.5 mm, and outer-row pieces running 3–6% heavy, are jacket failures even when the rubber is new. Pouring a thicker skin to "save the jacket cost" usually spends more rubber and still bananas at the edge.

Cost drivers we actually quote:

• Envelope. A 400 × 400 mm countertop edge form is not a 120 mm coaster jacket.
• Split. A two-part mother mold with keys on both halves is more shop time than a one-piece open-back board.
• Material. Plaster is cheap and chips. Resin and fiberglass survive wet concrete vibration better. A printed jacket is fast for a proto and may not be the production spare you warehouse.
• Keys. CNC bosses that match the skin cost more to mill once and then save recast time. Clay-pip keys that were "free" on the first pour often will not register a spare skin.
• Finish and vents. A jacket that also locates a pour gate and a clamp pattern is a fixture, not a bucket.

Paying for a first jacket on the prototype does not automatically mint a warehouse spare. Write "spare jacket, same revision, matching keys" on the PI.

The photo that would prove a spare-jacket program is two shells with the same key paint and revision letter, sitting beside one unsanded master. A tote of extra 10A skins is not that photo.

Typical shop values

Caption: Typical shop values. Not a named invoice.

Common mix-up: spare jacket equals rotation quantity equals leftover plaster

Buyers add "+1 jacket" and expect a complete second tool. A jacket without a second skin does not double output; it only lets you keep running if the *shell* chips. Rotation quantity is extra *complete* tools so you can rest a tray — that is skins + jackets, and it is how you survive recast transit from Bao'an. Leftover plaster from the first pour, unkeyed, is not a spare. Archive duration for the master is a PO term; if the master is gone, a spare jacket cannot recast a torn face.

Worked example (anonymized)

A 300 × 300 × 30 mm plaster plaque, Shore ~15A skin, resin jacket with four corner keys. First year they ordered MOQ 20 skins and one jacket. The jacket chipped on a clamp. They had twenty floppy skins and no spare shell — sag showed up as 0.5–1.5 mm dish and thick outer plaques. Reorder: same revision, one spare jacket on the PI, keys copied from the CAD bosses, master archived. Rubber recast stayed a separate line. CAD was not recharged because the STEP was locked; a new clamp pattern would have been a jacket revision and another 3–7 day proto if the keys moved. This was a craft plaque, not a food cavity.

We would not recommend

We would not recommend stocking loose 10A skins without a keyed jacket "because silicone is cheap."

We would not recommend a plaster spare for a vibrating concrete dump if the production jacket is fiberglass — they will not wear the same.

We would not recommend raising Shore A to avoid paying for a spare jacket.

We would not recommend treating a tooling charge as perpetual free recast of jackets we did not archive.

flowchart TD
  A[Jacket failed or you fear downtime] --> B{Master unsanded and keys in CAD?}
  B -->|no| C[You cannot mint a matching spare — rebuild, then archive]
  B -->|yes| D{What do you actually need?}
  D -->|Shell chipped / lost| E[Spare jacket, same revision]
  D -->|Skin torn, jacket OK| F[Recast skin — different line]
  D -->|SKU cannot stop| G[Rotation: complete tools, not jacket-only]
  E --> H[Price the rigid half on the PI]

What to ask when you're buying a spare jacket

• Is the spare the same revision letter and the same key CAD as production?
• Plaster, resin, fiberglass, or print — and does it match the duty (dry soap vs wet concrete)?
• Does a spare jacket include clamp holes and gate location, or only the cavity backer?
• If I later recast skins, will they still register on both jackets?
• Who stores the master, and for how long?

Related: replacement / reorder, tooling archive, contact.

RFQ copy-pack — spare jacket as a line

Paste into [email protected]:

Existing revision letter Duty: food tray / resin / plaster / concrete (concrete is not food) Need: spare jacket only / recast skin / complete rotation tools Jacket material to match production Keys: CNC bosses copied / do not invent new pips Master: we keep / you archive / not sure If jacket CAD is new: USD $50 if modeling applies, then 3–7 business days after lock Production skins still MOQ 20 per design

Send the revision letter and whether the *shell* or the *skin* is what fails. We will price a matching jacket, not a tote of extra rubber. Phone +86 135 3006 2969. Xinhe Blvd, Shajing, Bao'an, since 2018.

FAQ

Is a spare jacket cheaper than another full mold? Usually yes, if the skin CAD and keys already exist. A new split or a bigger envelope is a new jacket tool, not a discount spare.

Do spare jackets count toward MOQ 20? MOQ 20 is pieces of the locked *design* — typically the skins. A jacket is a support shell. Ask us to line-item it so twenty skins do not get confused with twenty plaster shells.

Can I buy the spare jacket a year later? Only if the key CAD and the master still exist under archive terms. A tooling charge is not a forever warehouse promise.

Should the spare jacket be a 3D print because prints are fast? A print can be a proto shell. For wet concrete or a clamped food tray we would not assume a printed spare matches a fiberglass production jacket. Name the duty.

If the jacket is fine and the lip tore, do I still buy a spare jacket? No. That is a recast of the skin against the unsanded master. Buy the jacket when the *rigid half* is the failure you are insuring.