Most people arrive at this decision the same way: there is a 55-gallon drum of hydraulic oil at one end of the building, a tote of water-based coolant in the middle, and a couple of carboys of acid in a cabinet by the lab. One spill kit is not going to cover all three. So what do you actually stock, and how much of it?
The answer starts with the liquid, not the product. Sorbents are sold in three chemical families and several physical formats, and getting the family wrong is the mistake that turns a cleanup into an incident.
The three sorbent families
Manufacturers group sorbent by what it is chemically able to pick up, and they have converged on a colour scheme to signal it at a glance.
| Family | Conventional colour | Picks up | Do not use on |
|---|---|---|---|
| Universal (sometimes "maintenance" or "all-purpose") | Grey | Oil, water, coolants, cutting fluids, solvents and most non-aggressive chemicals | Concentrated acids and bases — suppliers specifically warn against using standard universal pads on concentrated acid |
| Oil-only | White | Petroleum-based fluids, paints and non-water-soluble chemicals | Water-based liquids; it is hydrophobic and repels them by design |
| Hazmat / chemical | Yellow | Aggressive chemicals including acids and bases, plus oil-based and water-based liquids | No chemical restriction appears in manufacturer guidance; the limiting factor is cost, not compatibility |
The oil-only distinction is worth dwelling on, because it is the one that has a genuinely useful physical property attached. Because oil-only media repels water, it floats. That is why booms deployed on or near open water are almost always oil-only: they sit on the surface, take up the hydrocarbon and leave the water behind. Indoors on a wet floor the same property works against you, so grey universal is the everyday choice for a plant floor that sees coolant, washdown water and oil in the same shift.
The colours are a convention, not a law
This matters because people occasionally cite the colour scheme as a compliance requirement. It is not. OSHA's safety colour rule at 29 CFR 1910.144 assigns red to fire protection equipment and danger, and yellow to marking physical hazards such as tripping and "caught in between" — it says nothing about sorbents at all. Industry commentary describes the absorbent colour scheme as voluntary alignment between manufacturers, adapted loosely from the general ANSI Z535.1 safety colour standard, rather than anything a regulator mandates. Treat the colours as a very useful shorthand your team can be trained on, and write the actual compatibility rule into your own spill procedure rather than relying on the colour alone.
Where the liquid is unknown or unlabelled — an unmarked drum, a puddle under a pallet nobody claims — the colour tells you nothing until you know what you are looking at. Spilfyter chemical classifier strips exist for exactly this: the manufacturer describes them as giving a fast visual indication of whether a substance is an acid, a base, an oxidizer or neutral, so responders choose a compatible sorbent and neutralizer instead of guessing.
Pads, rolls, socks, booms and loose sorbent
Format is about where the liquid is and what you want it to do. Most formats are sold in more than one chemical family, so the two choices are largely independent — but check, because some lines offer socks in universal only and booms in oil-only.
- Pads are the workhorse. Perforated sheets in light, medium and heavy weights, used both preventively under a known drip and reactively on a fresh spill. Buy heavier weights where you want fewer changeouts.
- Rolls are pads on a continuous length, torn to fit. They cover larger areas — alongside a walkway, down an aisle, under a machine line — and are chosen by traffic level, from light-duty up to mats rated for foot and forklift traffic.
- Socks are flexible tubes you use as a dike. Their job is not primarily to absorb the spill but to corral it — ringing a leaking drum, laying across a doorway, or blocking the run toward a floor drain. Three-inch by four-foot socks are a common size for machine bases and crevices.
- Booms are the heavy version of a sock, typically in five- and eight-foot lengths with clamps so they link end to end into a continuous barrier. They are the first line of defence when a spill reaches or threatens water, and for that duty they are oil-only.
- Loose sorbent and powders are poured rather than laid. They suit rough, uneven or outdoor ground where a sheet cannot sit flat, and they have to be swept or shovelled up afterwards. See sorbents and powders for granular options and pads, rolls and booms for sheet and tube formats.
A practical pattern for most sites: socks or booms first to stop the spread, pads to lift the bulk, then loose sorbent or a final pad pass on the residue.
Sizing a kit against your largest container
The instinct to size a kit against your largest single container comes from a real regulatory principle. EPA's SPCC rule requires secondary containment sized for "the entire capacity of the largest single container plus additional capacity to contain precipitation" (40 CFR 112.7(c)). That is a containment requirement, not a sorbent requirement, but it is the right mental model: your worst realistic single event is one container failing completely.
From there, vendors commonly apply a likelihood discount — roughly three-quarters of the worst-case volume where the container is handled routinely, half where it is handled occasionally, a quarter where it is rarely moved — and one widely published vendor guide pairs that with kit bands: 1–5 gallon containers to a 10–20 gallon kit, 10–20 gallon containers to a 25–40 gallon kit, and 30–55 gallon containers to a 50–65 gallon overpack. That is a rule of thumb from a supplier, not a regulation, and your own incident history should override it.
Two other points from the same guidance are worth taking seriously. Site kits so a responder can reach one within about 60 to 90 seconds of the likely spill point — a kit locked in a store room three buildings away is decorative. And match the kit's chemistry to the area, not to the site average: a universal drum kit near the coolant and hydraulic lines, a chemical kit such as the SPC Hazwik chemical drum kit near corrosives, checking the sorbent's stated compatibility against your own SDS before you buy. Where the drum itself may need to be contained, an overpack-drum kit like the Spilfyter 95-gallon universal overpack kit gives you a salvage drum and the sorbent in one unit. The full range sits under spill kits and stations.
The regulatory backdrop, briefly
EPA SPCC (40 CFR part 112)
The SPCC rule applies to facilities with an aggregate aboveground oil storage capacity of 1,320 gallons or more, counting only containers of 55 gallons or greater (112.1(d)(2)(ii) and 112.1(d)(5)), or completely buried storage of more than 42,000 gallons (112.1(d)(2)(i)). If you are over the line you need a plan, and secondary containment is central to it. Sorbent is not a substitute for engineered containment, but it is normally part of how a plan handles the spills containment does not catch.
OSHA HAZWOPER (29 CFR 1910.120)
HAZWOPER governs, among other things, emergency response to releases of hazardous substances. The line that matters for stocking decisions is the standard's own carve-out: "Responses to incidental releases of hazardous substances where the substance can be absorbed, neutralized, or otherwise controlled at the time of release by employees in the immediate release area… are not considered to be emergency responses." In other words, whether your own staff may clean a spill up with a kit, or must evacuate and call trained responders, depends on where a given spill falls against that definition — and that judgement belongs in your written emergency plan, made with your EHS lead, not decided at the moment of the spill.
This guide is educational and general. It is not legal advice, and it does not replace 40 CFR part 112, 29 CFR 1910.120, the safety data sheets for the chemicals you actually store, or your own written spill and emergency response plan.
This guide is educational. Selection and compliance remain the employer's responsibility under the applicable standard.