Chemical-resistant gloves can carry the EN ISO 374 beaker or flask symbol. The marking tells you that the glove has been tested against specified chemicals, but it does not mean the glove protects against every chemical or every exposure condition.
This guide explains the Type A, Type B and Type C classifications, the chemical code letters under the symbol and the difference between permeation, penetration and degradation. Always select gloves through a suitable chemical risk assessment and check the product’s technical information and safety data sheet.
What does EN ISO 374 test?
EN ISO 374 covers protective gloves against dangerous chemicals and micro-organisms. The chemical classification is based mainly on permeation, which is the movement of a chemical through the glove material at a molecular level after contact.
Permeation is not the same as:
- Penetration: a chemical passing through holes, seams, stitching or other imperfections without changing the material.
- Degradation: the glove material becoming weaker, swollen, brittle, sticky or otherwise damaged after chemical contact.
A glove may have a good permeation result but still be unsuitable if it degrades, is damaged, does not cover the required area or cannot be used safely for the task.
Types A, B and C
| Type | Minimum permeation performance | What it means |
|---|---|---|
| Type A | At least 30 minutes against at least 6 listed test chemicals, at performance level 2 or higher. | Higher tested chemical permeation performance across a wider selection of chemicals. |
| Type B | At least 30 minutes against at least 3 listed test chemicals, at performance level 2 or higher. | Tested against at least three listed chemicals. |
| Type C | At least 10 minutes against at least 1 listed test chemical, at performance level 1 or higher. | Tested against at least one listed chemical, with a shorter minimum breakthrough time. |
These types are not a simple ranking for every task. A Type A glove is not automatically the best choice for every chemical, and a Type C glove may be suitable for a specific lower-risk task if the assessment supports it. The actual chemical, concentration, temperature, contact time, movement and glove design all matter.
What do the code letters mean?
The letters beneath the chemical-protection symbol identify the test chemicals for which the glove achieved the stated permeation performance.
| Code | Test chemical |
|---|---|
| A | Methanol |
| B | Acetone |
| C | Acetonitrile |
| D | Dichloromethane |
| E | Carbon disulphide |
| F | Toluene |
| G | Diethylamine |
| H | Tetrahydrofuran |
| I | Ethyl acetate |
| J | n-Heptane |
| K | Sodium hydroxide 40% |
| L | Sulphuric acid 96% |
| M | Nitric acid 65% |
| N | Acetic acid 99% |
| O | Ammonium hydroxide 25% |
| P | Hydrogen peroxide 30% |
| S | Hydrofluoric acid 40% |
| T | Formaldehyde 37% |
The code letters identify specific laboratory test chemicals, not every chemical in a broad family. For example, a glove tested against toluene should not automatically be assumed to protect against every solvent.
How to read a glove marking
Type A: A J K L M N P T
This marking would indicate Type A performance against the listed test chemicals, provided the complete product information confirms the classification and test results.
Type B: A J K
This would indicate Type B performance against three listed test chemicals. The glove may still be unsuitable for other chemicals or for longer contact than its tested breakthrough time.
Type C
Type C indicates the minimum chemical classification has been met for at least one listed test chemical. Check the product information to identify the chemical and the performance level.
Example: Capitol II chemical-resistant glove
The Capitol II Dual Colour Latex Gauntlet manufacturer datasheet identifies the glove as EN ISO 374-1:2016 Type A with the code letters A K L M N P T. The listed test chemicals include methanol, sodium hydroxide 40%, sulphuric acid 96%, nitric acid 65%, acetic acid 99%, hydrogen peroxide 30% and formaldehyde 37%.
The same datasheet states that the glove passed protection testing for bacteria and fungi, but that protection against viruses was not tested. It also warns that chemical movement, rubbing, degradation and changes in the glove’s physical properties can reduce the actual usable time.
Bacteria, fungi and viruses
A separate biological-protection marking relates to resistance against micro-organisms under EN ISO 374-5. A glove may be identified as passing bacteria and fungi penetration testing. Where virus protection has also been tested and passed, the product information should specifically identify virus protection, usually with the word VIRUS.
Do not assume that a chemical-protection flask symbol means protection against bacteria, fungi or viruses. Check the complete marking and the manufacturer’s instructions.
Permeation time is not a safe wear-time guarantee
Breakthrough time is obtained under specified laboratory conditions. It is not a promise that the glove can be worn for exactly that length of time in every workplace.
Actual protection can be reduced by concentration, temperature, pressure, flexing, stretching, abrasion, mixed chemicals, contamination, sweat, damaged material and contact with the cuff or unprotected skin. For corrosive chemicals, degradation can be especially important.
Never wait until a chemical can be smelled or felt before changing gloves. Follow the risk assessment, product instructions and established replacement procedure.
Choosing the right chemical glove
- Identify the exact chemical, concentration, temperature and form of contact.
- Check the safety data sheet and the manufacturer’s chemical-resistance table.
- Confirm both permeation and penetration performance where relevant.
- Check degradation information, thickness, cuff length, grip and dexterity.
- Make sure the glove covers the area that could be exposed, including the wrist and forearm where necessary.
- Consider whether the glove is compatible with other PPE and the task.
- Replace gloves when damaged, contaminated, degraded or past their planned service time.
Do not use a glove only because it has a chemical pictogram. Match the glove’s code letters and test data to the actual substance.
Latex and wearer considerations
Some chemical-resistant gloves contain natural rubber latex. Check the material information and provide a suitable alternative where latex sensitivity or allergy is a concern. The wearer should inspect gloves before use and report skin irritation or other problems promptly.
Find chemical-resistant gloves
Browse the Safety Gloves collection for available protective gloves.
For abrasion, cut, tear, puncture and impact markings, read EN388 Glove Markings Explained. For more PPE guidance, return to the Trade Guides hub.
Safety reminder
This guide is general information only. Chemical glove selection should be based on a competent risk assessment, the manufacturer’s current test data, the safety data sheet and the actual conditions of use. No glove protects against every chemical, and no test result removes the need for safe handling, ventilation, training and other controls.
Last reviewed: September 2026.