Chemical resistance tells you whether a tile surface is damaged by household cleaners, pool salts, acids and alkalis. Stain resistance tells you how easily common stains can be removed. Both are tested to parts of ISO 10545 and reported as classes.
For most indoor floors, good porcelain passes both easily. They matter more for kitchens, laboratories, food plants, pools and commercial floors that are cleaned with strong chemicals.
Chemical resistance: ISO 10545-13
In this test, tile samples are exposed to set chemicals for a set time and then inspected for visible change. Results are given as classes. A is the best, followed by B and C.
Glazed tiles carry a G in the class and unglazed tiles a U. The tests are grouped like this:
- Household chemicals and swimming pool salts, reported as GA, GB or GC for glazed tiles and UA, UB or UC for unglazed.
- Low-concentration acids and alkalis, reported as GLA, GLB or GLC (and ULA, ULB, ULC for unglazed).
- High-concentration acids and alkalis, reported as GHA, GHB or GHC (and UHA, UHB, UHC for unglazed).
European data sheets for group BIa porcelain show a minimum of class B for household chemicals and pool salts, with acids and alkalis as declared values. For a kitchen or bathroom, class A or B for household chemicals is normal. For a laboratory, a dairy or a plant that uses strong acid cleaners, ask for the high-concentration result.
Stain resistance: ISO 10545-14
In this test, stains such as oil, iodine and a green staining agent are left on the surface, then removed with increasingly strong cleaning methods. Results run from class 5, where the stain comes off with warm water, down to class 1, where it cannot be removed.
Glazed porcelain usually scores well because the glaze is closed. Polished unglazed porcelain can score lower, because polishing opens tiny pores on the surface. A good factory seals or nano-treats polished surfaces for this reason, as covered in nano polishing and how long it lasts.
Which results to ask for
- For homes, ask for the household chemicals class and the stain class on the test report.
- For restaurants and kitchens, ask for stain resistance against oil, and acid resistance for areas near food preparation.
- For pools, ask for the swimming pool salts result and frost resistance if outdoors.
- For laboratories and factories, ask for the high-concentration acid and alkali classes.
- For polished tiles, ask whether the stain test was run on the polished surface as sold.
Check that the report comes from an accredited laboratory and names the exact design and finish. A report for a matt tile says nothing about the polished version of the same design. Our guide on reading a lab certificate shows what to check.
Glazed tiles for food or drink areas may also need a lead and cadmium release test to ISO 10545-15, depending on your market's rules. Ask your customer what the project specification requires.
Next step
We collect test reports, check that they match the product, and arrange independent lot testing when your market needs it. To set the right tests for your range, book a free sourcing review.