The Group I / Group II classifications cited above originate from Guideline 4, "Fungus-Inert Materials," Table 4-I (p. 4-2), reproduced verbatim below. Item names appear exactly as published. Parenthetical notes under select entries are KasperCalc annotations, added to map the specification's generic polymer-family terminology to the trade names used elsewhere on this page.

This same list is codified in MIL-STD-810. Section 4.4 of MIL-HDBK-454B directs Group II materials to the fungus test defined in Method 508, and MIL-STD-810H reproduces the identical list as Method 508.8, Annex B, Table 508.8B-I ("Fungi susceptibility of materials"), citing MIL-HDBK-454 as its source. The two documents present a single classification, not independent ones. MIL-STD-810H includes the following caution:

"Although the basic (documented) resistance of materials to fungal growth shown below is helpful in the design of new materiel, it is unreliable in determining the fungal susceptibility of complex materials, and the use of testing by analysis is discouraged. … The below Table is not a comprehensive list and does not necessarily reflect modern day formulations of materials."

This caution reflects the same principle underlying this page: a family classification establishes a baseline, not a per-compound guarantee. Compound-level test results follow in the next two sections.

^1/ Literature shows that under certain conditions polyamides may be attacked by selective micro-organisms. However, for military applications, they are considered group I. (Footnote reproduced verbatim from the source table.)

Parker's US O-Ring Handbook reports individual fungus ratings for forty-five compounds, tested per MIL-STD-810F, Method 508.5. Thirty are non-nutrient; fifteen support fungal growth.

A rating of 0 or 1 indicates the compound is non-nutrient to fungus growth. A rating above 1 indicates it supports growth.

Results vary within a single polymer family. Among fluorocarbons, VX065-75 and VM125-75 score 0, while V0747-75 and V0680-70 score 2 and support growth. Among nitriles, fifteen of nineteen compounds tested came back non-nutrient despite the family's reputation as a fungal food source. Family classification does not determine compound-level performance.

PASS rating ≤ 1, non-nutrient to fungus growth FAIL rating > 1, supports fungus growth

Compound numbers are reproduced exactly as printed, including the legacy nitrile designation "47-071," which predates Parker's current letter-prefix numbering. ^* V1289-75 carries an asterisk in the source table whose footnote text was not included in the excerpt available here; V1289-75 has since been discontinued and replaced by VG130-75.

Compounds that appear only in the older European list: N0741-75 (NBR), C0557-70 (CR), L0677-70 (FVMQ), V3860-75 and V8545-75 (FFKM). These were recorded as passing under MIL-STD-810B and have no entry in the newer US table. Note that C0557-70 is the only chloroprene ever recorded as passing — all three neoprenes in the newer table fail.

Still no data at all for perfluoroelastomer (FFKM) beyond the two legacy European entries, for TFE/propylene (Aflas®), or for any non-Parker compound — Chemours Viton®, 3M Dyneon™, Syensqo Tecnoflon®, Daikin Dai-El™, Greene Tweed Chemraz®, DuPont Kalrez®, Trelleborg Isolast®, Freudenberg Simriz® and PPE Perlast® all publish extensive chemical-resistance data but no fungus results.

Compound-to-specification mapping below is sourced directly from Parker's Aerospace Industry Material Reference Guide (ORD 5800, rev. 10/20/2025) and Material Offering Guide (ORD 5712) — this is what determines which physical compound gets molded when a drawing calls out an AMS or MIL spec, independent of fungus resistance. It does not mean every listed compound has documented fungus test data; cross-check against the Verified Compounds table above for that.

Corrections to common cross-reference confusion: AMS7270 ("O-Ring, Molded, Butadiene-Acrylonitrile (NBR) Rubber Material," per its SAE title) is a nitrile (NBR) spec, not EPDM — it does not appear in Parker's current aerospace cross-reference, so no specific Parker compound is confirmed against it here. MIL-R-6130 covers cellular/sponge silicone rubber, not chloroprene. SAE AS8791 specifies PTFE back-up ring (retainer) material, not an elastomer seal compound. MIL-R-6855 (general-purpose Buna-N) was superseded by AMS-R-6855 and is now MIL-PRF-6855. MIL-DTL-5516 ("Packing, Preformed, Petroleum Hydraulic Fluid Resistant, 160°F," current rev. D, 9/30/2025) is itself a preformed-packing dimensional/performance spec — like AS8791, not a raw elastomer material spec — that happens to be built from NBR compatible with MIL-PRF-5606 hydraulic fluid. MIL-PRF-5606, MIL-PRF-83282, and MIL-PRF-87257 are hydraulic fluid specs, not elastomer material specs — compound-to-fluid compatibility is covered separately on the O-Ring Chemical Compatibility page. AMS7261 is not a fluorocarbon spec despite sitting near the FKM AMS72xx block — it's phosphonitrilic (FZ) fluoroelastomer, a distinct specialty polymer family (see the new FZ row above). "AMS7262" does not appear to exist as a standalone number; it is most likely a mis-citation of AMS7261/2, a sub-part of AMS7261 covering the 75–85 durometer grade of that same FZ family.

Genuinely unresolved after this pass: whether a stand-alone "AMS7262" exists separate from AMS7261/2 could not be confirmed either way through public search. Treat any drawing callout to "AMS7262" as needing direct confirmation against SAE's current spec index rather than this table.

Full compound listing from Parker's O-Ring Material Offering Guide (ORD 5712): approximately ninety compounds across thirteen elastomer families, with temperature range, color, and applicable MIL, AMS, NSF, and UL callouts. This table is not filtered for fungus resistance; cross-check against the Verified Compounds table above for that data.

Reproduced from ORD 5712's "Material Offering" section (pp. 6–17 of the guide). Some compound numbers appear in parentheses in the original as legacy Wynn's Precision designations; those are omitted here for brevity and can be found in the source PDF. Not every row carries a MIL/AMS/NSF/UL callout — where none is printed, Parker's own "Recommended For" application text is reproduced as-is.

• MIL-HDBK-454B — General Guidelines for Electronic Equipment, Guideline 4 (Fungus-Inert Materials), Table 4-I. Group I (fungus-inert) and Group II (fungus-nutrient) material classification; reproduced verbatim above.
• MIL-STD-810H — Environmental Engineering Considerations and Laboratory Tests, Method 508.8 (Fungus). 28-day exposure, Grade 0/1 pass criterion. Annex B (Table 508.8B-I) reproduces the MIL-HDBK-454 material list under MIL-STD-810's own numbering.
• ASTM G21 — Standard Practice for Determining Resistance of Synthetic Polymeric Materials to Fungi. Source of the 0–4 rating scale used throughout this page.
• Parker O-Ring Handbook (US), "Fungus Tests on Compounds" — fungus testing per MIL-STD-810F, Method 508.5. Forty-five compounds with individual ratings, split into non-nutrient (rating ≤ 1) and supports-fungus-growth (rating > 1). Primary source for the pass/fail table above, and the only located source that publishes failures as well as passes.
• Parker O-Ring Handbook (ORD/PTD 5705) — O-Ring Division Europe, §7.17 "Fungus-resistant compounds," Table 7.14. An older, pass-only list tested to MIL-STD-810B, Method 508. Superseded by the US table where the two conflict (E0540-80, E0652-90 and V0747-75 pass here but fail under 810F), but retained above as the only source for five compounds absent from the newer table.
• Parker Aerospace Industry Material Reference Guide (ORD 5800) — rev. 10/20/2025. Source for the military and aerospace specification cross-reference table.
• Parker O-Ring Material Offering Guide (ORD 5712) — full PDF. Source for compound descriptions, hardness, colour, temperature ranges and the full compound catalog table below.
• Trade-name ownership and polymer identification per manufacturer and distributor material data (Curbell, Boedeker, Ensinger, Röchling, and individual manufacturer datasheets).
• Family ratings are not per-compound test data. Except where a compound is explicitly named in the Table 7.14 list above, every rating on this page reflects the typical behaviour of a base polymer family. Fillers, plasticizers, colorants, and specific compounding can move an individual grade substantially — NBR compounds have been reported anywhere from 0 to 4 depending on formulation. A family rating is a starting point for material selection, not evidence about a part.
• A "?" rating is an instruction to look up the compound, not a warning about the material. For fluorocarbon it means the tested compounds genuinely disagree — VM125-75, VX065-75 and V1289-75 scored a perfect 0 while V0747-75 and V0680-70 failed at 2 — so any single family number would be misleading. For TFE/propylene it means nothing has ever been tested. In neither case does "?" imply the material is likely to support growth.
• Absence from the test tables is not a failure. Parker's European list is explicitly non-exhaustive ("further compounds available on request"), and both tables predate many compounds currently in production. An untested compound is unmeasured, not suspect. Note however that the US table does publish failures, so a compound listed there with a rating above 1 is a genuine documented failure, not an absence of data.
• Verify before use. For critical applications, confirm resistance by ASTM G21 or MIL-STD-810 Method 508 testing of the specific compound and grade being purchased, rather than relying on any family rating — including the ones on this page. Where fungus-nutrient materials are unavoidable, MIL-HDBK-454B §4.3 permits their untreated use inside hermetically sealed enclosures.
• Specification status changes. Several specifications and compounds referenced here have been cancelled, superseded, or discontinued (AMS-R-83248 approvals, V0709-90, V1164-75). Legacy items are retained deliberately because aerospace drawings continue to call them out for years after production ends, but current procurement should be checked against the live specification index.
• For informational use only. This lookup tool is an independent compilation provided as an engineering aid, and is not endorsed by or affiliated with any manufacturer listed. Trade names are the property of their respective owners. Results must be verified by a qualified engineer before use in any safety-critical or flight application. KasperCalc assumes no liability for material selection decisions made using this data.