SLS Nylon Masters for Platinum RTV Molds | RUUIPON

An SLS or MJF nylon print can be a dimensionally useful RTV master after you de-powder it, close the porosity, and slug-test platinum on a hidden land. Straight from the bake it is a dusty, open-cell object: powder packed in a serif becomes a bubble nest in the cavity, and unsealed nylon drinks A/B and can leave a tacky or pitted face. This is not the SLA oligomer essay and not the FDM layer-line essay. Nylon is usually chemically calmer than a raw photopolymer, and geometrically calmer than FDM stairs, but it is the porosity champion. If the SKU is a food logo, we would not pour against raw grey nylon and hope the dust "just blows off."

RUUIPON pours around sealed sintered masters in Bao'an, Xinhe Blvd, Shajing, since 2018. Prototype is 3–7 business days after CAD lock — lock includes "this nylon is sealed and quiet." Production is MOQ 20 pieces per design. Simple 3D is USD $50 when that CAD scope applies. Mix 1:1 or 10:1; platinum shrink typically about 0.1–0.3%. Steel/LSR *parts*: wydsilicone.com. SLA protocol: SLA wash/UV/seal.

Does not apply when the print is FDM or SLA, when the nylon part is a mold *box* you already sealed as a flask, or when you wanted dyed MJF color to copy as a food tint. We would not spec the dye as a 177.2600 argument. Photos-only without a print still go through from photos.

Powder in a serif is a bubble nest

Media blast and compressed air get the easy dust. Counters, undercuts, and 0.3 mm gaps keep powder that vacuum then lifts into the platinum. You will see a crater field that maps the type, not random cup bubbles.

Seal has to *close* the surface, not just tint it. A thin CA wipe can crust and still leave pinholes. A high-build compatible coating, fully cured, then a 20 g platinum slug on a hidden land, is the gate. If the slug pits, the seal soaked in — another coat, or remodel a non-porous master for $50 when that CAD scope applies.

Dimensional: sintered nylon can be the most accurate plastic print in the building and still grow a seal-film that moves a logo depth. Measure after seal, not after the bake. Scale stacks with platinum 0.1–0.3%. ISO 3302-1 M2 is a rubber class, not an SLS tolerance.

The photo that would prove an SLS master: raking light into a letter counter *after* de-powder and *after* seal, millimetre scale, slug puck beside the print. A grey sintered mascot on a table does not prove the counters are empty.

flowchart TD
  A[SLS / MJF part] --> B[De-powder counters]
  B --> C[Seal until porosity closes]
  C --> D[Measure after seal]
  D --> E[20 g platinum slug on hidden land]
  E --> F{Pits or tack?}
  F -->|yes| G[Recoat or $50 remodel]
  F -->|no| H[CAD lock, flask, 1:1 or 10:1, vacuum]
  G --> E

Dye, vapor smooth, and food

MJF dye sits in the porous skin. It can transfer onto a craft dump and it is not a food colorant. Vapor smoothing (where used) can close porosity and leave a chemistry you must slug-test — some smoothers are platinum-unfriendly until fully flashed. Name the post-process.

Food wells: we would rather CNC or a sealed SLA for fine type. SLS is a strong pick for a rugged craft master, a jacket plug, or a large form that would warp in FDM. Structure Decision still runs on the shape: flat back → open-back. Deep hooks → split. Nylon toughness does not make a one-piece peel safe.

Hollow SLS with escape holes still holds powder. Plug or print solid for a master that will see vacuum.

Failure: pitted type after a "clean" blast

Symptom: logo wells are a crater map; sprues are fine.

Cause: powder or open cells in the counters; seal too thin.

Confirm: raking light on the master after blast; slug pits against the print, cup rubber is fine.

Fix: more seal, or remodel. Do not torch the rubber face. Do not "just vacuum longer" — vacuum lifts more dust into the mix if the master is still dirty.

Typical shop values

Caption: typical shop values, not a named PO.

Jacket plugs and flask walls are a different nylon job

Sintered nylon is often the right *jacket plug* or *flask wall* even when it is the wrong *cavity master*. A plug you will bolt into a mother mold can live with a slightly dusty land if that land never sees the dump face. A cavity master cannot. Say which job the print is doing on the RFQ. We have watched buyers send one MJF part and write "use this for the face and the box." The face wants a closed, slug-tested skin. The box wants leak-tight joints and a clay-coil dam — porosity in a flask wall drinks platinum the same way a serif does, and you find out when the cup runs short.

If the nylon is only a flask, seal the inside corners and water-test before A/B. If the nylon is only a plug, we still do not want loose powder in the shop vacuum. Keep those prints in a craft tote, not on the food bench.

SLS habits we would not recommend

We would not recommend raw, freshly de-powdered nylon as a food-logo master.

We would not recommend dyeing the print and calling that a food tint test.

We would not recommend vapor-smoothing without a slug.

We would not recommend blasting so hard you round the type you needed.

We would not recommend a new sintered print every reorder; keep the sealed one.

Worked example: MJF badge, powder in the counters

PU badge, 70 mm, MJF nylon, buyer said "already bead-blasted." First platinum slug pitted on the wordmark land. We sealed, slug passed, poured 1:1 into a two-part flask with keys. Prototype 3–7 business days after CAD lock of the sealed millimetres. $50 CAD applied because the STEP still needed a shut face. Production MOQ 20 of that design.

Mix-up: SLS is "production plastic so it must be pour-ready"

Sintered nylon is a good engineering print. It is still porous. Related: master model options, CNC master to pour.

What to ask when you're buying an SLS path

• SLS or MJF, dyed or natural, vapor-smoothed?
• Photos of letter counters after de-powder?
• Seal system and a slug result?
• Food type vs craft form?
• After lock, 3–7 business days, then MOQ 20 / design?

RFQ copy-pack — SLS nylon master

Paste into [email protected]:

Object: RTV mold from sintered nylon, not an LSR/HCR part Process: SLS / MJF, dye, vapor smooth Dump: food or craft Seal done? Slug result? File: STL + raking-light photos of counters + millimetre scale CAD: pour-ready OR USD $50 3D if we must remodel Prototype 3–7 business days after CAD lock, then MOQ 20 per design Who keeps the sealed master

Send counter photos, not "it's nylon so it's fine." We seal or remodel — not a blank quote request. Phone +86 135 3006 2969. Xinhe Blvd, Shajing, Bao'an. Shop since 2018.

FAQ

Can SLS nylon be a silicone mold master? Yes, after de-powder, a porosity-closing seal, and a 20 g platinum slug. Raw grey nylon is a dust source.

Why are there bubbles only in the letters? Powder or open cells in the counters. Vacuum will not save a dirty serif. Seal or remodel.

Is MJF dye safe for chocolate molds? We would not treat dye as a food-contact argument. Food wells want a clean, sealed, quiet master — often CNC or sealed SLA for type.

Do you charge $50 if I already sintered the part? USD $50 when we still have to model. A sealed, measured print with a locked shut can skip that scope.

Should I order a new SLS part for the reorder? Keep the sealed master. A new bake will not match millimetres. Tooling charge ≠ unrestricted ownership. Clock is 3–7 business days after lock; MOQ 20 per design.