Glossary

CraftBrewer glossary — homebrewing science and materials terminology

A

ABNS (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.
ABV (Alcohol By Volume): The percentage of alcohol in a finished beer, expressed as a volume fraction. Calculated from the difference between original gravity (OG) and final gravity (FG) after fermentation is complete: ABV = (OG − FG) × 131.25. A typical homebrew ale runs 4–6% ABV; strong beers can exceed 10%.
Airlock: A one-way valve fitted to the fermenter lid that allows CO₂ produced during fermentation to escape while preventing air and contamination from entering. Filled with sanitiser solution or cooled boiled water. The rate of bubbling gives a rough indication of fermentation activity, but the absence of bubbling does not confirm fermentation is complete — gravity measurement is the reliable indicator. 3-piece and S-type designs are both common and functionally equivalent for homebrew use.
All-grain brewing: A brewing method in which the brewer converts raw malted grain into fermentable wort entirely from scratch — mashing the grain to convert starches to sugars, sparging to rinse the grain bed, and boiling the resulting wort with hops. Gives complete control over the recipe but requires the most equipment and time. The fourth and final stage in the BrewClub brew sequence.

B

Beer 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.
Boiling: Heating wort to a rolling boil (typically 60–90 minutes) to sterilise it, drive off unwanted compounds (including DMS precursors), concentrate sugars, and isomerise hop alpha acids into bitterness. Boiling is a hot-side process — it does not occur in Brew 1, which uses a pre-boiled kit.

C

CF (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.
Chelating 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).
CIP (Clean-in-Place): A method of cleaning the interior of pipework, vessels, and equipment without disassembly, using pumped cleaning and rinsing solutions. Standard in commercial and microbrewery settings. Requires dedicated CIP equipment and is out of scope for small-batch homebrewing.

D

DDBSA (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.
DES (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.
DoC (Declaration of Conformity): A manufacturer's written statement that a food contact material or article complies with the applicable EU regulations (primarily 1935/2004 and 10/2011). Required at each stage of the commercial supply chain, but not legally required to be provided to end consumers at retail.

E

EPDM (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.
ESC (Environmental Stress Cracking): Failure of a polymer under the combined action of mechanical stress and chemical exposure. The failure mode of POM DuoTight collars under repeated ABNS WDC cycles. Occurs below the material's normal stress threshold when chemical exposure is present.

F

FKM (Fluoroelastomer): The ISO/ASTM class designation for the family of fluorinated synthetic rubbers commercially known as Viton. High chemical resistance, but cure system (peroxide vs. polyamine) significantly affects compatibility with phosphoric acid.
Fresh Wort Kit: Ready-made wort produced by a professional brewery and packaged for home fermentation. Supplied concentrated — typically at 15 litres — with the option to dilute up to 20 litres. The brewer handles everything from fermentation onwards: sanitising, pitching yeast, dry hopping, and packaging. Removes the mashing and boiling steps entirely. Currently only available in 15–20 litre minimum volumes, making small-batch brewing a challenge without splitting.

G

GMP (Good Manufacturing Practice): A set of regulated manufacturing requirements under EU Regulation 2023/2006 that food contact material producers must comply with. GMP covers controlled production environments, quality management systems, and traceability — ensuring that a food-approved resin is also processed in conditions that prevent contamination from non-food substances. A material can use an approved additive package and still fail GMP requirements if it is produced in a facility that also processes industrial compounds without adequate separation.
GPPS (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.

H

HDPE (High-Density Polyethylene): A polyolefin plastic used in fermenter taps and spray bottles. Slightly better chemical barrier properties than PP. EU Regulation 10/2011 compliant.
HDT (Heat Deflection Temperature): The temperature at which a polymer specimen deflects by a defined amount under a specified load, measured under standardised test conditions (ASTM D648 or ISO 75). HDT is a practical indicator of the upper service temperature for a structural plastic article under mechanical stress — above it, the material creeps and deforms rather than returning to its original shape. HDT varies substantially between polymer grades, wall thickness, and geometry, so a material's published HDT range is a guide; the specific article's rated service temperature from its manufacturer is the correct reference for any given use.
Hopping: Adding hops to wort or beer at various stages of the brewing process. Hot-side hop additions during the boil contribute bitterness and some flavour. Cold-side additions (dry hopping) after fermentation contribute aroma and flavour without bitterness. The timing, quantity, and variety of hop additions are among the most influential variables in beer flavour.
Hydrolysis: The chemical reaction in which a molecule is split by water, typically at a bond that connects two parts of the molecule. In food contact materials, hydrolysis is the primary mechanism by which acid or alkaline cleaning solutions attack susceptible polymers — particularly those with ester linkages (PET, Tritan, PC) or ether linkages (POM). Polymers with all-carbon backbones (PP, HDPE, PTFE) have no hydrolysable bonds and are inherently resistant to aqueous chemical attack.

I

IPA (Isopropyl Alcohol): A common solvent and disinfectant alcohol (propan-2-ol). Occasionally referenced in chemical compatibility contexts. Not used as a primary sanitiser in homebrewing. Note: the abbreviation IPA also refers to India Pale Ale in brewing contexts — spell out India Pale Ale in full throughout this guide to avoid ambiguity.

K

Krausen: The thick, rocky foam layer that forms on top of fermenting wort during active fermentation. Produced by CO₂ rising through the liquid and carrying proteins, hop compounds, and yeast cells to the surface. Krausen typically peaks within the first 24–72 hours of fermentation and then falls back into the beer as activity slows. It is normal and harmless. The fermenter needs enough headspace to accommodate it — typically at least 20% of the batch volume — or it can push out through the airlock.

M

Mashing: Soaking crushed malted grain in hot water at a controlled temperature to convert starches to fermentable sugars.
Molar: A unit of concentration in chemistry, abbreviated M (or mol/L). One molar means one mole of substance per litre of solution — a mole being 6.02 × 10²³ molecules, a counting unit that makes reactive quantities practical to compare. For acids, molar concentration directly reflects how many acid molecules are present per litre, and therefore how reactive the solution is. It is less intuitive than percentage by mass (which is how most compatibility charts express concentration), but useful for cross-referencing chemical literature. As a scale reference: 85% phosphoric acid (the standard industrial/laboratory grade) is approximately 14.6 M; the dry residue left by StellarSan after a WDC is approximately 5.4 M; cola drinks contain phosphoric acid at roughly 0.05 M.

N

NEIPA (New England India Pale Ale): A hazy, hop-forward IPA style characterised by high dry hop additions, soft bitterness, and haze from hop oils and proteins. Among the most oxidation-sensitive styles in common homebrewing — oxygen exposure causes rapid flavour degradation. PET bottle conditioning imposes a meaningful shelf-life limitation for NEIPA; Oxebar barrier PET or stainless kegging is strongly preferred for extended storage.
NR (Natural Rubber): Vulcanised latex of Hevea brasiliensis. Used in budget grommets and washers. Carries N-nitrosamine precursor risk from sulphur-cure accelerators — invisible to inspection. Replace immediately with EPDM.

O

OML (Overall Migration Limit): The maximum total amount of all substances that may migrate from a food contact material into food or a food simulant under EU Regulation 10/2011, set at 10 mg/dm² of contact surface (or 60 mg/kg of food for articles where dm² is impractical to measure). The OML is a ceiling on total migration; individual substances also have their own Specific Migration Limits (SMLs) which may be more restrictive. A DoC that shows overall migration within 10 mg/dm² confirms OML compliance but does not reveal how close individual additives are to their own SMLs.
Organoleptic: Relating to the sensory properties of a food or drink — taste, smell, appearance, and texture. EU food contact regulations require that materials do not cause unacceptable organoleptic changes to food.
Original Gravity (OG): A measure of the sugar content of wort before fermentation begins. Yeast converts these sugars to alcohol and CO₂ during fermentation, so original gravity is the starting point for calculating the final alcohol content of the beer. Measured with a hydrometer or refractometer. Higher OG means more fermentable sugar available and therefore higher potential ABV.
OTR (Oxygen Transmission Rate): A measure of how quickly oxygen permeates through a packaging material. Lower OTR means better oxygen barrier and longer shelf life for packaged beer. Multilayer PET (Oxebar) and stainless steel have significantly lower OTR than plain PET.

P

PBW (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.
PET (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.
Pitch: To add yeast to wort to begin fermentation. Pitching rate — the quantity of yeast added relative to the volume and strength of the wort — affects fermentation speed, yeast health, and flavour. For BrewClub brews, a single packet of dried yeast is the correct pitch rate for a standard kit batch.
POK (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.
Polyolefin: A class of polymers made by polymerising simple alkene (olefin) monomers — propylene for polypropylene, ethylene for polyethylene. The resulting polymer has an all-carbon backbone with no functional groups susceptible to hydrolysis, which is the primary reason polyolefins have excellent resistance to acids, alkalis, and aqueous environments. PP and HDPE are both polyolefins.
POM (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.
PP (Polypropylene): A semi-crystalline polyolefin plastic widely used in fermenter buckets, lids, taps, and airlocks. Excellent chemical resistance across all homebrewing chemical environments. EU Regulation 10/2011 compliant.
PS (Polystyrene): A family of transparent, rigid styrene-based plastics used in homebrewing airlocks and accessories. Three grades appear in this register: GPPS (General-Purpose Polystyrene), SAN (Styrene-Acrylonitrile copolymer), and Styrolux SBC (styrene-butadiene block copolymer). All three are visually indistinguishable. Grade is often unspecified by manufacturers — treat as GPPS if unknown, which is the most conservative assumption for ABNS and DES compatibility.

R

REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals): EU Regulation (EC) 1907/2006. The primary EU chemicals regulation framework, which governs SDS format and substance disclosure requirements.
RIC (Resin Identification Code): A numerical code moulded into the base of plastic articles to identify the polymer type, introduced by the Society of the Plastics Industry (now PLASTICS) in 1988 and represented by three chasing arrows forming a triangle with the number inside. Codes 1–7 cover the most common polymer families: 1 = PET, 2 = HDPE, 3 = PVC, 4 = LDPE, 5 = PP, 6 = PS, 7 = other. The RIC identifies the polymer backbone only — it says nothing about the additive package, food grade status, or GMP compliance. Food grade and industrial grade articles of the same polymer carry the same RIC code.

S

SAN (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.
Saponify: The chemical reaction between a fatty acid and an alkali to form soap (a soluble salt of the fatty acid) and glycerol. In brewing cleaning, alkaline cleaners saponify the lipid components of yeast cell walls and hop resins, converting them into water-soluble compounds that can be rinsed away.
SBC (Styrene-Butadiene block Copolymer): A transparent, impact-resistant styrene-based thermoplastic used in the Enolandia 6-bubble airlock (cod. 13526) and spiral airlock (cod. 09000). The polybutadiene mid-block provides better impact resistance than GPPS through crack arrest, but introduces different chemical vulnerability. ABNS and DES ratings match GPPS (B single WDC / D accumulated WDC) — crack-arrest benefit erodes with accumulated WDC cycles as butadiene domains absorb concentrated DDBSA residue. Food contact compliance confirmed by Declaration of Conformity.
SBR (Styrene-Butadiene Rubber): A synthetic rubber sharing NR's unsaturated backbone and sulphur-cure chemistry. Same N-nitrosamine precursor risk as NR. Replace immediately with EPDM.
SDS (Safety Data Sheet): A standardised document providing detailed information on a chemical substance or mixture — composition, hazards, handling, and regulatory status. The primary source for confirmed chemical composition data. EU format governed by REACH Regulation (EC) 1907/2006.
Sequester: To chemically bind and effectively remove an ion from active participation in solution, typically by chelation. Sequestering agents in cleaning products prevent calcium and magnesium ions from causing scale deposits or interfering with the cleaning chemistry. In brewing, sequestration is the primary mechanism by which chelating agents prevent beer stone redeposition.
SML (Specific Migration Limit): The maximum permitted amount of a substance that may migrate from a food contact material into food or a food simulant, set by EU Regulation 10/2011. Expressed in mg/kg of food.
Sparging: Rinsing the grain bed with hot water after mashing to wash out remaining fermentable sugars. In all-grain brewing, sparging recovers sugars that would otherwise be left behind in the grain. Common methods include batch sparging (adding water in discrete additions) and fly sparging (continuous slow rinsing). Not required for extract or partial mash brewing.
Steeping: Soaking crushed grain in hot water to extract colour, flavour, and unfermentable sugars without converting starches. Used in extract brewing with specialty malts. Unlike mashing, steeping does not require precise temperature control or enzymatic conversion — it is the simpler of the two grain processes.
SVHC (Substance of Very High Concern): A substance identified under REACH as having serious hazardous properties — carcinogenic, mutagenic, toxic to reproduction, or persistent/bioaccumulative. Cyclic siloxanes D4 and D5 found in silicone are SVHC-listed.

T

TPV (Thermoplastic Vulcanisate): A rubber-toughened thermoplastic that combines the chemical resistance of a vulcanised rubber with the processing advantages of thermoplastics. Santoprene is an EPDM/PP TPV used in the Oxebar Gen2 elbow and NukaTap valve shuttle.
Transfer: Moving beer from one vessel to another — most commonly from the fermenter to kegs or bottles for packaging. How the transfer is done affects oxygen pickup and contamination risk. Options range from simple gravity transfer via a tap, through hose-assisted filling, to fully closed CO₂-assisted transfer that minimises oxygen contact throughout.
Trub: The layer of sediment that collects at the bottom of the fermenter during and after fermentation. Composed of dead yeast cells, hop particles, and proteins precipitated during the boil (hot break) or cooling (cold break). Beers transferred off the trub are cleaner and clearer, but a small volume loss is inevitable — typically 0.5 to 1 litre per batch depending on fermenter geometry and dry hop additions.

W

WDC (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.
Wort: Liquid extracted from malted grain during mashing and boiling, before fermentation. The starting point for beer.