Silicone vs Plastic Gummy Molds on Deposit Lines

If you're choosing silicone versus plastic gummy molds, you're choosing dump and hygiene, not a brand war.

Rigid plastic (often polycarbonate) owns simple, drafted cups on invert-and-knock lines. Platinum RTV — poured on a master, usually jacketed — owns flex dump, peelable undercuts, reverse logos, and rooms that won't run starch. Hybrids exist because depositors like stiffness and cavities like rubber. Food-contact files differ: rubber 21 CFR 177.2600 extractives / LFGB versus plastic declarations. Starch is the third path, not a plastic.

What PC still owns

PC plates are stiff. Nozzles hit them. Knock dump is a known station. Simple vitamin cups and jelly cups that are drafted bowls still belong here if the plastic food-contact file matches the market. PC won't flex an undercut out. Deep mascots and closed loops trap. Fine reverse logos can mold in PC and lock the gel. Scratches don't heal. If the plant already runs PC chocolate plates, a geometrically similar gummy cup can share racks and operators — that's a real cost advantage, not a reason to force a cartoon undercut into PC. Other plastics appear in catalogs; you own the food-contact file and washer temperature.

Where platinum RTV earns the tray

RTV earns the PO when dump needs flex, undercuts or mascot ears a knock will tear, logo relief that must leave a gel (not contracted chocolate), hybrid faces in a frame, or no starch and PC can't do the shape. Mid Shore or a dual-pour plus jacket so the tray doesn't flop. Tin-cure isn't the silicone in this comparison. Kitchen one-ups aren't production trays.

RTV can cup after a hot stack, miss pitch if too soft, and pick up knife cuts (knives mean dump failed). Those are design problems, not a reason to return to PC if PC can't dump the shape. Piece-weight works on both: volume is geometry. RTV's extra job is holding that volume after wash (ovaling). PC's extra job is not cracking at knock and not scratching the show face.

Common mix-up: silicone is always better for vitamin gummies

A lot of RFQs treat "premium silicone" as the vitamin default. In the shop that usually means you've skipped a simple cup that would knock out of PC. Piece-weight is milliliters on either. Silicone shows up for shapes, flex dump, and hygiene versus starch. Operators will scratch PC with a dump assist and cut RTV with a knife; both are process failures. A GMP hall that forbids knives will punish an undercut that still needs a peel. A candy hall that knocks PC all day will punish a floppy RTV sheet that needs two hands.

Hybrids: PC or aluminum carrier with RTV cavities; dual-pour firmer back; PC for SKU A and RTV for SKU B on the same envelope. They fail on seals (crevices, tin-cure beads) and walking inserts. Cost of ownership is master plus jackets plus lost trays from bad seals — not a printed dump life. Don't use a blog number for dumps. Compare mother-pattern cost, spare fleet, washer fit, scrap from tears vs scratches, lab scope, changeover.

Climate: RTV stacked hot on a dock will take a set. PC will crack if cold-knocked. A warped RTV tray isn't "silicone losing"; it's logistics PC might have survived.

What to ask when you're buying the vs

• Is starch allowed? If yes and it prints, mogul first.
• Is the cavity a drafted cup with knock dump? PC first.
• Flex, undercut, or reverse logo that gels lock? Platinum RTV.
• Does the depositor demand a stiff envelope anyway? Jacketed hybrid.
• Food-contact method matched to the material — don't paste 177.2600 onto PC.

Then Shore (if RTV), pitch, volume, one-up, master. The vs is over before you pick a color. When geometry is borderline, run both one-ups on the same slurry, same dump temperature, same weigh.

Example

Borderline mascot: PC 24-cup knock tray missed ears; 32-cavity platinum RTV, 14 mm dump depth, Shore 25A, aluminum jacket, flex dump, hit 2.2 ml. Same nozzle pitch. We didn't pick RTV because it felt premium; the piece voted.

When the vs is the wrong argument

If starch is still on the table, it's a three-way. If you're comparing kitchen silicone trays to production PC, kitchen trays lose on pitch before material science starts. LSR injection of silicone *parts* isn't this comparison. Polish will not make PC take an undercut.

Related reading: material selection, how to choose, gummy trays.

Decision RFQ

• Dump motion, starch allowed?, undercut yes/no
• Target grams, nozzle pitch, tray size
• PC file vs 177.2600 extractives / LFGB if RTV
• One-up of *each* on the real gel if you're on the fence
• Jacket / hybrid seal design if the head wants stiffness

Send grams, formula, nozzle pitch, tray envelope, and dump method. We'll recommend PC, jacketed platinum RTV, or a hybrid from that trial — not from a catalog Shore.

We would not recommend RTV as a vitamin default

We would not recommend "premium silicone" when a drafted cup already knocks out of PC. We would not paste 177.2600 onto a plastic plate. We would not polish PC harder hoping an undercut leaves. Kitchen silicone trays lose this vs on pitch before material science starts.

flowchart TD
  ST{Starch allowed and it prints?} -->|yes| M[Mogul first]
  ST -->|no| K{Knock cup, no undercut?}
  K -->|yes| P[PC + plastic food-contact file]
  K -->|flex / undercut / reverse logo| R[Jacketed platinum RTV]
  P --> T[Borderline: one-up of EACH on the same gel]
  R --> T

Typical shop values: borderline mascot after the piece voted

| Item | Typical shop value | | --- | --- | | Piece-weight target | 4.0 g (cavity volume × measured slurry density; fill-to-brim or fill-to-line stated) | | Outer-row vs center | 3–6% heavy if the loaded tray sags under the nozzles | | Loaded-tray edge sag | 0.5–1.5 mm without a flat jacket | | Cavity Shore | 10A–20A platinum RTV skin + rigid jacket | | Platinum linear shrink | 0.1–0.3% (cut the master so poured pitch lands) | | Mix | Platinum 1:1 or 10:1 if RTV wins the dump trial | | PC extra job | Not cracking at knock; not scratching the show face |

Caption these as typical shop values, not a measurement on your PO.

FAQ

Is RTV always better for vitamin gummies? No. A simple cup on a knock line can stay PC. RTV shows up for shapes, flex dump, and some hygiene preferences versus starch. Piece-weight is volume on either.

Can I use the same 21 CFR 177.2600 report for a PC plate? No. That section is rubber articles. PC needs its own plastic food-contact documentation. LFGB sensory thinking doesn't copy-paste between families.

Why do RTV trays miss nozzles when PC didn't? The RTV tray flexed or cupped. Raise stiffness, add a jacket, or dual-pour the back. Don't blame the depositor until the tray is flat.

Will PC take an undercut if we polish it harder? Polish isn't flex. The gel has to climb out. Undercuts want RTV or a change of shape. A harder knock breaks the piece.

Are kitchen silicone trays the silicone side of this vs? No. Production RTV is a registered, jacketed tray. Kitchen trays lose the vs on pitch before material science starts.