Standard explainer · EN ISO 374
Chemical gloves carry the most information-dense marking in PPE: a pictogram, a type letter and a string of code letters that name the chemicals the glove actually resisted in testing. Read properly, the label answers the only question that matters — will this glove survive this substance long enough?
The system
EN ISO 374-1 grades chemical gloves by how many of its standard test chemicals they resist, and for how long. Type A: at least 6 chemicals for 30+ minutes each. Type B: at least 3 chemicals, 30+ minutes. Type C: at least 1 chemical, 10+ minutes — splash-brief protection only. The letters printed under the beaker pictogram identify which chemicals passed: each code letter (A–T) is a named substance — A is methanol, K is sodium hydroxide (caustic), J is n-heptane, and so on through the list.
Breakthrough time is the honest number: it's how long the chemical takes to permeate the glove at molecular level — invisible, and unrelated to visible damage. A glove rated 30 minutes against caustic is a 30-minute glove, however intact it looks. Degradation (the material swelling or hardening) is tested separately, and disposable nitrile against a named solvent may be a minutes glove: right for a splash-and-doff task, wrong for immersion.
The markings
| Marking | Means | Buying note |
|---|---|---|
| Beaker pictogram + letters | Tested chemicals by code letter | Match the letters to YOUR chemicals via the datasheet |
| Type A / B / C | Breadth and duration of resistance | Type A for sustained work; C is splash-only |
| Microorganism pictogram (374-5) | Bacteria and fungi barrier | Add VIRUS marking for virus-tested |
| Polymer (nitrile, butyl, neoprene…) | The actual chemistry doing the work | Material choice beats brand choice |
| EN 388 marking | Mechanical performance, separately | Chemical gloves still meet cut and abrasion needs — or don't |
In practice
Questions
Each letter under the beaker pictogram is a specific test chemical from the EN ISO 374-1 list — A is methanol, K is sodium hydroxide, J is n-heptane and so on. The letters shown are the chemicals that glove resisted for the required breakthrough time in testing; match them against the substances you actually handle.
Test breadth and duration: Type A resisted at least six of the standard chemicals for 30+ minutes each, Type B at least three for 30+ minutes, and Type C at least one for 10+ minutes. Type C is short-splash protection; sustained chemical work wants Type A in the right polymer.
Until breakthrough — the tested time the chemical takes to permeate the material, which happens invisibly and regardless of visible condition. Track the time in contact, not the look of the glove, and treat the manufacturer's per-chemical permeation data as the real specification.
Everything decoded here is stocked as certified garments and PPE, embroidered where it makes sense.