Materials

Homebrewing equipment is made from a surprisingly wide range of materials. A single fermenter setup may contain five or six distinct plastics, two or three elastomers, and one or more metals — each with its own chemical resistance profile, its own food contact regulatory history, and its own failure mode under the chemicals applied to it.

This register catalogues as many as possible. Each material has its own page covering what it is, where it appears in homebrewing equipment, its food contact regulatory status, and its compatibility with the chemical environments it is likely to encounter.

Before reading the individual pages, the framework pages earlier in this section are worth having in hand:

• The EU food contact compliance framework — what makes a material food grade, how to read a Declaration of Conformity, and what to do when documentation is absent — is in Food contact compliance.
• The sanitisers and cleaners these ratings apply to are described in Sanitising and Cleaning.
• The wet-dry cycle (WDCWDC — Wet-Dry Cycle The process by which liquid applied to a surface evaporates, leaving non-volatile components concentrated as a dry residue. A single WDC deposits concentrated DDBSA and phosphoric acid on every sanitised surface. Repeated WDC events without cleaning cause residue to accumulate, progressively increasing exposure. Post-brew cleaning resets accumulation to zero. See: The wet-dry cycle model.) model — which explains why a material rating at working dilution can be different from its rating under concentrated dry-residue conditions — is in The wet-dry cycle model.
• Toxicology implications for specific materials are in Toxicology and migration.
• A worked example of how cleaning and sanitising chemistry failures play out in real equipment is in the DuoTight case study.

Rating system

Five grades are used throughout:

• A — compatible. No meaningful degradation under typical homebrewing use conditions.
• B — use with caution. Compatible in most conditions but with specific limitations around concentration, temperature, contact duration, or geometry.
• C — limited use. Marginal compatibility; acceptable only in specific, controlled circumstances.
• D — avoid. Significant degradation risk or meaningful toxicology concern.
• X — incompatible. Do not use.

Where a rating carries important qualifications — and many do — those qualifications are in the individual page text, not collapsed into the grade. A B rating with five lines of caveats is a different thing from a B rating with one.

Reading the columns

ABNSABNS — Acid-Based No-Rinse Sanitiser The class of acid-based sanitisers used in homebrewing, combining phosphoric acid with an anionic alkylbenzenesulfonate surfactant. The acid creates a low-pH environment hostile to microorganisms; the surfactant disrupts cell membranes. Examples: Star San, Sanipro Rinse, StellarSan, Chemsan. Approved for use on food-contact surfaces without rinsing when used at the manufacturer's specified dilution. — acid-based no-rinse sanitiser (Star SanSAN — Styrene-Acrylonitrile copolymer A transparent plastic used in some airlocks and equipment. The acrylonitrile content gives better chemical resistance than GPPS, particularly against DDBSA in acid-based sanitisers. Rated A for ABNS, unlike GPPS which is rated B/D., StellarSan, Sanipro Rinse, Chemsan, ChemiPro SanSAN — Styrene-Acrylonitrile copolymer A transparent plastic used in some airlocks and equipment. The acrylonitrile content gives better chemical resistance than GPPS, particularly against DDBSA in acid-based sanitisers. Rated A for ABNS, unlike GPPS which is rated B/D.). Ratings reflect working-dilution contact without WDCWDC — Wet-Dry Cycle The process by which liquid applied to a surface evaporates, leaving non-volatile components concentrated as a dry residue. A single WDC deposits concentrated DDBSA and phosphoric acid on every sanitised surface. Repeated WDC events without cleaning cause residue to accumulate, progressively increasing exposure. Post-brew cleaning resets accumulation to zero. See: The wet-dry cycle model. accumulation — sanitiser applied for the label contact time and either drained, wiped, or used in a way that does not allow concentration to build through repeated wet-dry cycles. This is the CFCF — Concentration Factor How many times more concentrated the non-volatile residue is compared to the original working solution, after evaporation. CF at complete drying is set by the product's working dilution: CF = 1,000 ÷ dose in mL/L. For StellarSan at 1.5 mL/L, CF ≈ 667.=1 scenario in the WDC model. WDCWDC — Wet-Dry Cycle The process by which liquid applied to a surface evaporates, leaving non-volatile components concentrated as a dry residue. A single WDC deposits concentrated DDBSA and phosphoric acid on every sanitised surface. Repeated WDC events without cleaning cause residue to accumulate, progressively increasing exposure. Post-brew cleaning resets accumulation to zero. See: The wet-dry cycle model. conditions arise wherever sanitiser can dry on a surface and be reapplied before cleaning — a fermenter tap sprayed before each sample pull is a real example. Where the rating changes under WDCWDC — Wet-Dry Cycle The process by which liquid applied to a surface evaporates, leaving non-volatile components concentrated as a dry residue. A single WDC deposits concentrated DDBSA and phosphoric acid on every sanitised surface. Repeated WDC events without cleaning cause residue to accumulate, progressively increasing exposure. Post-brew cleaning resets accumulation to zero. See: The wet-dry cycle model. conditions — whether a single concentrated dry cycle or accumulated cycles — this is flagged in the individual page and in the footnotes below, and is worth checking before using equipment that may see multiple WDCWDC — Wet-Dry Cycle The process by which liquid applied to a surface evaporates, leaving non-volatile components concentrated as a dry residue. A single WDC deposits concentrated DDBSA and phosphoric acid on every sanitised surface. Repeated WDC events without cleaning cause residue to accumulate, progressively increasing exposure. Post-brew cleaning resets accumulation to zero. See: The wet-dry cycle model. cycles.

DESDES — Disinfectant Ethanol Sanitiser ChemiPro DES. An ethanol-based (70–80%) sanitiser with no non-volatile residue. Evaporates completely, leaving no WDC risk. A-rated for all common homebrewing materials. — disinfectant ethanol sanitiser (ChemiPro DESDES — Disinfectant Ethanol Sanitiser ChemiPro DES. An ethanol-based (70–80%) sanitiser with no non-volatile residue. Evaporates completely, leaving no WDC risk. A-rated for all common homebrewing materials., food-grade ethanol at 70–80%). Fully volatile — leaves no residue, no WDCWDC — Wet-Dry Cycle The process by which liquid applied to a surface evaporates, leaving non-volatile components concentrated as a dry residue. A single WDC deposits concentrated DDBSA and phosphoric acid on every sanitised surface. Repeated WDC events without cleaning cause residue to accumulate, progressively increasing exposure. Post-brew cleaning resets accumulation to zero. See: The wet-dry cycle model. risk.

Cleaning — covers all dedicated cleaning products used in homebrewing at working concentrations and typical temperatures (ambient to 60 °C). Three categories appear in this register, matching the taxonomy in the Cleaning guide:

• Alkaline percarbonate (PBWPBW — Powdered Brewery Wash A sodium metasilicate and percarbonate-based alkaline cleaner widely used in brewing. Removes organic soil through alkaline hydrolysis. A-rated for all common homebrewing plastic and elastomer materials at working concentrations., StellarClean, ChemClean, ChemiPro Wash, Enzybrew 10) — the dominant homebrewing cleaning category; sodium percarbonate releases hydrogen peroxide and sodium carbonate. Formulations vary in their secondary components: metasilicate content (Five Star PBWPBW — Powdered Brewery Wash A sodium metasilicate and percarbonate-based alkaline cleaner widely used in brewing. Removes organic soil through alkaline hydrolysis. A-rated for all common homebrewing plastic and elastomer materials at working concentrations.'s EU-market formulation carries sodium metasilicate at 20–35% — comparable to StellarClean; the US-market formulation appears to differ, though this has not been confirmed from primary sources), chelating agentsChelating agent A molecule that binds to metal ions (such as calcium and magnesium) at multiple points, forming a stable ring-like complex that holds the ion in solution and prevents it from precipitating or redepositing. In brewing cleaners, chelating agents dissolve beer stone and prevent scale from reforming on surfaces after cleaning. Common chelating agents in brewing cleaners include EDTA (ethylenediaminetetraacetic acid) and TKPP (tetrapotassium pyrophosphate). (EDTA in PBWPBW — Powdered Brewery Wash A sodium metasilicate and percarbonate-based alkaline cleaner widely used in brewing. Removes organic soil through alkaline hydrolysis. A-rated for all common homebrewing plastic and elastomer materials at working concentrations., TKPP + EDTA in ChemiPro Wash), and surfactants. These differences matter for some materials.
• Phosphate-based alkaline (Grainfather High Performance Cleaner) — sodium tripolyphosphate (STPP) as the primary cleaning agent; effective for beer stoneBeer stone A grey-white mineral scale that deposits on fermenter walls, taps, and heat exchanger surfaces from wort and beer. Composed primarily of calcium oxalate (from oxalic acid in malt) with some calcium tartrate. Resists plain water rinsing but dissolves readily in alkaline cleaners (PBW, StellarClean) and in acid sanitisers at working dilution. and mineral scale.
• Oxidising (ChemiPro OXI, StellarOxy) — sodium percarbonate without significant alkaline boosters; cleaning action is purely oxidative. The most material-benign profile of the three categories.

Caustic products (VWP, containing 30–50% NaOH) are out of scope for this guide — see the Cleaning page.

Where the Cleaning rating carries a dagger (A†, B†), the overall rating applies to the most benign product in the category. The footnote explains which cleaner subtypes require additional caution for that material.

Beer/wortWort Liquid extracted from malted grain during mashing and boiling, before fermentation. The starting point for beer. — product contact at ambient to fermentation temperatures. Covers: hot wortWort Liquid extracted from malted grain during mashing and boiling, before fermentation. The starting point for beer. at transfer (up to 95 °C where the vessel is rated for it), fermenting wortWort Liquid extracted from malted grain during mashing and boiling, before fermentation. The starting point for beer. (pH 5.0–5.4), standard beer (pH 3.8–4.4, 4–12% ABV), high-ABV beer (up to ~20%), and sour beer (pH 3.2–3.5, lactic and acetic acid dominant). For most materials the rating is uniform across this range — where it is not (e.g. a material that handles standard beer but degrades under prolonged sour contact), the individual page explains the distinction.

Quick-reference table

Material	Common usage	ABNSABNS — Acid-Based No-Rinse Sanitiser The class of acid-based sanitisers used in homebrewing, combining phosphoric acid with an anionic alkylbenzenesulfonate surfactant. The acid creates a low-pH environment hostile to microorganisms; the surfactant disrupts cell membranes. Examples: Star San, Sanipro Rinse, StellarSan, Chemsan. Approved for use on food-contact surfaces without rinsing when used at the manufacturer's specified dilution.	DESDES — Disinfectant Ethanol Sanitiser ChemiPro DES. An ethanol-based (70–80%) sanitiser with no non-volatile residue. Evaporates completely, leaving no WDC risk. A-rated for all common homebrewing materials.	Cleaning	Beer/wortWort Liquid extracted from malted grain during mashing and boiling, before fermentation. The starting point for beer.
Polypropylene (PP)	Fermenter buckets, lids, taps, airlocks	A	A	A	A
High-density polyethylene (HDPE)	Taps, spray bottles, chemical storage	A	A	A	A
Polyethylene terephthalate (PET)	FermZilla vessel, Oxebar keg, PETPET — Polyethylene terephthalate The plastic used in the FermZilla All Rounder, Oxebar mini keg, and PET bottles. Recycling code ♻️1. Extensively tested for food contact with carbonated beverages. Do not exceed 40 °C when cleaning. bottles	A	A	A†	A
Polystyrene — GPPS and SAN	Airlocks (unconfirmed grade: GPPSGPPS — General-Purpose Polystyrene The standard grade of polystyrene — amorphous, rigid, transparent, and inexpensive. Carries RIC code 6. Susceptible to DDBSA-driven environmental stress cracking (ESC) under WDC conditions — rated B at working dilution, D under accumulated WDC. Confirmed in Enolandia compact airlock (cod. 14037/14038) and cylindrical fermenter with float (cod. 11965) by Declaration of Conformity.; confirmed grade: SANSAN — Styrene-Acrylonitrile copolymer A transparent plastic used in some airlocks and equipment. The acrylonitrile content gives better chemical resistance than GPPS, particularly against DDBSA in acid-based sanitisers. Rated A for ABNS, unlike GPPS which is rated B/D.)	B / A	A	A	A
EPDM rubber	Fermenter grommets, tap washers	B‡	A	A	A
Silicone (platinum-cured)	Bungs, hose, tap washers	B	A	A	A
Polyoxymethylene (POM / Acetal)	John Guest fittings, older DuoTight	D–X	A	A	A††
Polyketone (POK)	DuoTight fittings, RAPT Pill body	A	A	A	A
Nylon 12	Accessories, some sealing components	A	A	A	A
Natural rubber (NR)	Budget grommets and washers — replace	D	C–D	—	D
Styrene-butadiene rubber (SBR)	Budget grommets and washers — replace	D	C–D	—	D
Nitrile rubber (NBR)	Some bottling wand seals	C	C	A	A
Polycarbonate (PC)	Siphons, bottling wands, sight glasses, some airlocks; older carboys	A	A	A	A††
EVABarrier	Beer line tubing	A	A	A	A
Santoprene (thermoplastic vulcanisate, TPV)	Oxebar Gen2 elbow, NukaTap shuttle	A–B	A	A	A
Stainless steel 304/316L	Cornelius kegs, mini kegs, NukaTap body	A	A	A	A
Glass	Airlocks, test jars, bottles	A	A	A	A
Aluminium	Foil covers for flask openings (no direct liquid contact); aluminium cans have an internal polymer liner — the aluminium is not the food-contact surface	B/D§	A	A	A
Crown cap body (tinplate or TFS steel)	Crown cap shell	A	A	A	A
LOW2	FermZilla lid O-ring, Corny keg lid O-ring	B	A	A	A
Viton — peroxide-cured	Spray bottle seals, O-rings	A–B	B	A	A
Viton — polyamine-cured	Spray bottle seals, O-rings	C	B	A	A
PTFE	Thread seal tape, filter discs, gaskets	A	A	A	A
Tritan copolyester	FermZilla Tri-Conical collection container	B	A	A	A

† PETPET — Polyethylene terephthalate The plastic used in the FermZilla All Rounder, Oxebar mini keg, and PET bottles. Recycling code ♻️1. Extensively tested for food contact with carbonated beverages. Do not exceed 40 °C when cleaning. Cleaning: A for oxidising cleaners (ChemiPro OXI) and low-metasilicate percarbonate (PBWPBW — Powdered Brewery Wash A sodium metasilicate and percarbonate-based alkaline cleaner widely used in brewing. Removes organic soil through alkaline hydrolysis. A-rated for all common homebrewing plastic and elastomer materials at working concentrations., Enzybrew 10). High-metasilicate percarbonate cleaners (StellarClean, ChemClean, ChemiPro Wash) require limited contact time (30 minutes maximum) and should not be used hot. Follow manufacturer guidance for each vessel. See the PET page for the full analysis.

†† Rating applies if undegraded — see individual page for toxicology context.

‡ EPDMEPDM — Ethylene Propylene Diene Monomer A saturated-backbone elastomer rubber used in fermenter grommets and tap washers. Better chemical resistance than NR or SBR. Rated B for DDBSA in realistic homebrewing use with post-batch cleaning. rates U (unsatisfactory) against concentrated DDBSADDBSA — Dodecylbenzenesulfonic acid The active surfactant in acid-based no-rinse sanitisers (ABNS). A long-chain anionic surfactant that disrupts microbial cell membranes at low pH. Non-volatile — it concentrates on surfaces as water evaporates. in laboratory compatibility references. Under the bounded WDCWDC — Wet-Dry Cycle The process by which liquid applied to a surface evaporates, leaving non-volatile components concentrated as a dry residue. A single WDC deposits concentrated DDBSA and phosphoric acid on every sanitised surface. Repeated WDC events without cleaning cause residue to accumulate, progressively increasing exposure. Post-brew cleaning resets accumulation to zero. See: The wet-dry cycle model. conditions typical of homebrewing — one partial wet-dry cycle per brew, arrested by fermentation humidity, reset by post-batch rinsing or cleaning — the practical rating is B. See the EPDM page and the WDC model (grommet as a bounded case) for the full analysis.

§ Aluminium: B where ABNSABNS — Acid-Based No-Rinse Sanitiser The class of acid-based sanitisers used in homebrewing, combining phosphoric acid with an anionic alkylbenzenesulfonate surfactant. The acid creates a low-pH environment hostile to microorganisms; the surfactant disrupts cell membranes. Examples: Star San, Sanipro Rinse, StellarSan, Chemsan. Approved for use on food-contact surfaces without rinsing when used at the manufacturer's specified dilution. contacts the surface at working dilution and is drained or wiped off before drying (CFCF — Concentration Factor How many times more concentrated the non-volatile residue is compared to the original working solution, after evaporation. CF at complete drying is set by the product's working dilution: CF = 1,000 ÷ dose in mL/L. For StellarSan at 1.5 mL/L, CF ≈ 667.=1, no WDCWDC — Wet-Dry Cycle The process by which liquid applied to a surface evaporates, leaving non-volatile components concentrated as a dry residue. A single WDC deposits concentrated DDBSA and phosphoric acid on every sanitised surface. Repeated WDC events without cleaning cause residue to accumulate, progressively increasing exposure. Post-brew cleaning resets accumulation to zero. See: The wet-dry cycle model.). D where ABNSABNS — Acid-Based No-Rinse Sanitiser The class of acid-based sanitisers used in homebrewing, combining phosphoric acid with an anionic alkylbenzenesulfonate surfactant. The acid creates a low-pH environment hostile to microorganisms; the surfactant disrupts cell membranes. Examples: Star San, Sanipro Rinse, StellarSan, Chemsan. Approved for use on food-contact surfaces without rinsing when used at the manufacturer's specified dilution. is allowed to dry on aluminium — even a single wet-dry cycle concentrates phosphoric acid to ~52% by mass (CFCF — Concentration Factor How many times more concentrated the non-volatile residue is compared to the original working solution, after evaporation. CF at complete drying is set by the product's working dilution: CF = 1,000 ÷ dose in mL/L. For StellarSan at 1.5 mL/L, CF ≈ 667.≈667), which is genuinely aggressive toward the aluminium oxide passivation layer. Manufacturer warnings against use on aluminium apply specifically in this scenario. The foil-over-starter-flask case is B because there is no direct liquid contact with the sanitiser — see the Aluminium page for the full analysis and safety margins. Other aluminium uses (pots, utensils) should be treated as D unless a no-WDCWDC — Wet-Dry Cycle The process by which liquid applied to a surface evaporates, leaving non-volatile components concentrated as a dry residue. A single WDC deposits concentrated DDBSA and phosphoric acid on every sanitised surface. Repeated WDC events without cleaning cause residue to accumulate, progressively increasing exposure. Post-brew cleaning resets accumulation to zero. See: The wet-dry cycle model. workflow can be confirmed.

‖ Crown cap liners: Standard caps use a PVC-free polyethylene liner — A for ABNSABNS — Acid-Based No-Rinse Sanitiser The class of acid-based sanitisers used in homebrewing, combining phosphoric acid with an anionic alkylbenzenesulfonate surfactant. The acid creates a low-pH environment hostile to microorganisms; the surfactant disrupts cell membranes. Examples: Star San, Sanipro Rinse, StellarSan, Chemsan. Approved for use on food-contact surfaces without rinsing when used at the manufacturer's specified dilution. and all routine sanitising. Oxygen-scavenging caps have a moisture-activated iron-based scavenging layer: any liquid contact (including ABNSABNS — Acid-Based No-Rinse Sanitiser The class of acid-based sanitisers used in homebrewing, combining phosphoric acid with an anionic alkylbenzenesulfonate surfactant. The acid creates a low-pH environment hostile to microorganisms; the surfactant disrupts cell membranes. Examples: Star San, Sanipro Rinse, StellarSan, Chemsan. Approved for use on food-contact surfaces without rinsing when used at the manufacturer's specified dilution.) activates and depletes this layer before the cap is applied, destroying the scavenging function. The cap still seals; the O₂ absorption is gone. Do not sanitise O₂-scavenging caps with any liquid. See the Crown caps page for the correct handling procedure.

Notes on identification

Several of the most important distinctions in this register — natural rubber versus EPDMEPDM — Ethylene Propylene Diene Monomer A saturated-backbone elastomer rubber used in fermenter grommets and tap washers. Better chemical resistance than NR or SBR. Rated B for DDBSA in realistic homebrewing use with post-batch cleaning. grommets, polystyrene airlock grade (general-purpose polystyrene versus SANSAN — Styrene-Acrylonitrile copolymer A transparent plastic used in some airlocks and equipment. The acrylonitrile content gives better chemical resistance than GPPS, particularly against DDBSA in acid-based sanitisers. Rated A for ABNS, unlike GPPS which is rated B/D.), peroxide-cured versus polyamine-cured Viton, POMPOM — Polyoxymethylene Also known as acetal or Delrin. An engineering thermoplastic used in John Guest push-fit fittings and older DuoTight collars. Susceptible to acid-catalysed chain-unzipping under WDC conditions, releasing formaldehyde. Rated D–X for ABNS.→ Full details versus POKPOK — Polyketone An engineering thermoplastic used in current KegLand DuoTight push-fit fittings and the RAPT Pill body. Replaced POM due to POM's vulnerability to acid-catalysed degradation under WDC conditions. A-rated for all homebrewing chemicals.→ Full details push-fit collars — cannot be determined by visual inspection alone. Materials that are chemically different can be visually identical.

When equipment documentation does not specify the material of elastomeric or plastic components to this level of detail, the safest approach is: ask the manufacturer directly, cross-reference the product against a known compliant specification, or choose a different product where the material is documented. In the case of natural rubber — where the toxicology risk is invisible to inspection — there is no acceptable alternative to confirmation or replacement.

The Documentation problem page covers this gap in detail.