FDA vs LFGB on Custom RTV Molds: Two Flask Methods

If you're putting a custom RTV food mold into US grocery, a German account, or both, FDA 21 CFR 177.2600 and LFGB aren't two names for the same flask. 177.2600 extracts the finished platinum RTV cavity — after post-cure and wash — in distilled water and n-hexane at reflux, against milligram-per-square-inch ceilings. LFGB is Germany's food law; labs methodize silicone largely through BfR Recommendation XV under Regulation (EC) 1935/2004.

A pass on one isn't a pass on the other. Dual-market programs run both on the same jacketed SKU after the same production post-cure. Platinum addition-cure RTV is the usual chemistry. Don't treat LFGB as “FDA plus 20 percent.” If the PDF is full of cold-runners, you're looking at a molded-part RFQ, not this mold.

Common mix-up: LFGB includes 177.2600, or the other way around

A lot of RFQs treat the two as nested — “do the stricter one and we're done.” In the shop that usually means one PDF gets printed on both cartons, and the first retailer quality team that actually reads the method list sends it back.

The solvents differ. The units differ (mg/in² reflux vs simulant migration and volatiles). The sensory panel has no US counterpart in 177.2600. Nested would be convenient, but that's not how the methods work. Write the market on the RFQ: US, DE-EU, or both, and name the object as a custom RTV mold (master, box, cavity, jacket), not as an LSR *part*.

What to ask when you're buying for US, EU, or both

• Which markets does this SKU actually ship into, and which methods are on the first-article plan: 177.2600, BfR XV / LFGB, or both?
• Which food types are you claiming (aqueous, acidic, fatty, alcoholic, dry), and will the lab flasks match that list?
• Is the specimen this platinum RTV recast, this color, this post-cure, or a sister spatula / plaque?
• For Germany, are volatiles and sensory in scope, and are simulants water / 3% acetic acid / 95% ethanol timed to real use (chocolate ambient vs oven batter)?
• Confirm current BfR XV text with the lab, because recommendations move.
• If someone wrote “FDA/LFGB included,” is that two method lines with two reports, or a blur?

What 21 CFR 177.2600 actually measures on the RTV face

The section isn't a sticker and isn't a product approval. FDA doesn't register a muffin or praline mold. You formulate inside the section, pour the platinum RTV against the master, post-cure and clean the cavity, and extract the food-contact surface.

Aqueous food: distilled water at reflux. First 7 hours, total extractives not to exceed 20 milligrams per square inch. Succeeding 2 hours, not to exceed 1 milligram per square inch. Fatty food: n-hexane at reflux. First 7 hours, not to exceed 175 milligrams per square inch. Succeeding 2 hours, not to exceed 4 milligrams per square inch.

Surface area as used matters. A thick jacketed baking mold and a thin gummy skin are different specimens even in the same compound if post-cure and surface-to-volume differ. Dry-food use is framed as suitability under GMP rather than those flasks. The section also expects a thoroughly cleansed article before food contact, so release left on the master and dust from the mother mold belong on the traveler. Composition lists still matter — you can't pass extraction on unlisted ingredients and call it good.

What LFGB plus BfR XV actually measures

Regulation (EC) 1935/2004 is the EU umbrella: food-contact materials shall not transfer constituents in amounts that endanger health or change the food. LFGB is how Germany polices that. BfR Recommendation XV is the silicone-specific recommendation.

A typical kitchenware stack for an RTV food mold includes composition / positive-list thinking, volatile organic matter (under-baked recasts fail here), migration against simulants matched to use, and an organoleptic check so no smell or taste is imparted. Acetic acid catches things n-hexane reflux doesn't, and ethanol does too. Sensory is why an under-post-cured platinum RTV cavity that smells like catalyst on the first chocolate pull can still fail Germany after a quiet US hexane column.

PAHs, specific metals, or other add-on screens appear when the lab or the buyer writes them. Put the use-case on the quote or you'll buy the widest, slowest scope.

Worked example: 24-cavity gummy bear, two retail doors

A brand wants a 24-cavity bear, about 18 mm tall, platinum RTV with registration keys and a rigid jacket, 1,000–2,000 dumps a month, shipping into US grocery and a German specialty account.

The US door wants 177.2600 on that finished sheet, food types named (gummies are often aqueous and acidic; write it). The German door wants LFGB/BfR XV on the same recast recipe: volatiles, simulants, sensory. Dual-market here means two reports on one master, one jacket, one pigment freeze — not a US hexane PDF with a German stamp, and not a factory spatula file. If the supplier instead quotes LSR injection steel for a molded gummy *toy*, that quote won't dump pectin.

Failing a flask is usually formulation, short post-cure, or testing the wrong specimen. It isn't fixed by switching Shore A on the jacket, and it isn't fixed by printing the other region's acronym on the carton.

When this article is the wrong quote

If you only sell freezer ice trays in the US and nobody asked for a German quality bar, a full kitchenware LFGB suite is the wrong spend. If the mold never touches food, both flasks are the wrong spend. If you actually need molded LSR *parts* for retail spatulas, you're on a parts OEM quote with a cold-runner, not this RTV cavity file. Geometry can override quantity: a 2 mm gummy skin and a 15 mm muffin wall don't share post-cure or surface-to-volume, even in the same compound.

Related reading: what food-grade means on an RTV mold, LFGB benefits on this cavity, certification guide, food-grade molds.

What to send for a dual-market (or single-market) lab plan

Copy this. “FDA/LFGB included” without these lines isn't comparable.

• Markets: US only, DE-EU only, or both
• Food types: aqueous, acidic, fatty, alcoholic, dry — and real contact time/temperature
• Specimen identity: SKU, color, platinum RTV, post-cure, master revision, jacket as shipped
• 177.2600 flasks: water, n-hexane, or both
• BfR XV scope: volatiles, listed simulants, sensory; PAHs/metals only if the buyer template asks
• Who pays the lab, and the retest trigger when pigment or the master changes

Send the production recast (not a plaque) plus the market list. We'll map flasks to food types and tell you if someone nested the two methods on the carton.

We would not recommend nesting the two methods on one carton

We would not recommend printing LFGB as "stricter FDA," or skipping 177.2600 because Germany already passed. We would not send a spatula plaque to stand in for this jacketed RTV recast. We would not buy an oven kitchenware LFGB suite for a US-only freezer ice sphere unless a buyer asked for that quality bar.

flowchart TD
  M[Markets on the RFQ] -->|US only| U[177.2600 water and/or n-hexane on this cavity]
  M -->|DE-EU only| G[BfR XV volatiles + simulants + sensory]
  M -->|both| D[Same platinum RTV, master, pigment, post-cure]
  D --> U
  D --> G
  U -.->|do not nest| G

Typical shop values: dual-market RTV food mold

| Item | Typical shop value | | --- | --- | | US aqueous flask | 20 mg/in² / 1 mg/in² water reflux (7 h + 2 h) | | US fatty flask | 175 mg/in² / 4 mg/in² n-hexane reflux (7 h + 2 h) | | BfR XV simulants | Water, 3% acetic acid, 95% ethanol, timed to real use | | Sensory | Organoleptic: no smell or taste imparted | | Specimen | Production recast, this color, this post-cure — not a 2 mm plaque for a 12 mm wall | | Chemistry | Platinum RTV 1:1 or 10:1; Shore 10A–20A + jacket |

Caption these as typical shop values. Confirm current BfR XV text with the lab.

FAQ

Does an LFGB report replace 21 CFR 177.2600 for a US-sold RTV gummy sheet? The solvents, units, and sensory requirement are different, so dual-market SKUs need both reports on the same cavity after the same production post-cure. Nested would be convenient, but that's not how the methods work.

Why does BfR XV use acetic acid and ethanol instead of n-hexane? Those are simulants matched to aqueous, acidic, and alcoholic use under the German/EU silicone stack. 177.2600 uses distilled water and n-hexane at reflux for aqueous and fatty repeated-use rubber. Each flask finds different migrants on the RTV face.

Can an under-baked platinum RTV recast pass the US hexane flask and still fail LFGB? Yes. Sensory (odor and taste) and volatile organic matter are common German failure modes that a hexane column doesn't score. Platinum addition-cure with a thickness-scaled post-cure is the usual dual-market start.

Is “FDA” on a German carton proof of 177.2600 on this mold? The word isn't a method. Ask for the regulation section, the food type, the specimen (this RTV SKU, not a sister spatula), and the lab report, and don't accept a fake certificate number in place of that file.

Do I need both tests for a freezer-only ice-sphere mold sold only in the US? If the market is US-only, 177.2600 on the finished two-piece RTV cavity is the rubber rule most buyers cite. LFGB is the wrong spend unless a buyer uses it as a quality bar. Write the actual market and food type; don't default to the widest scope.