A porcelain slab specification should describe the product, its test limits, its tolerances, its grade and its packing in terms that can be measured. If two people can read the same line and disagree, rewrite it.
Attach the specification to the purchase order and refer to it in the contract. It becomes the standard for samples, inspection and any claim. Below is a structure you can use.
1. Product description
- Product type: glazed or unglazed porcelain slab, with water absorption of 0.5% or less.
- Nominal size and work size in millimetres, with the allowed tolerance, and whether the slab is rectified.
- Nominal thickness in millimetres, with the allowed tolerance, and whether a mesh or fibre backing is applied.
- Body type: standard, colour-matched or vein-through, with the approved cut sample as reference.
- Finish: polished, matt, satin, textured or other, and any sealer or surface treatment.
- Design name and code, number of faces, and matching scheme: random, book-match or continuous.
Background on these choices
Our guides on porcelain slab thickness and full-body porcelain slabs explain these choices.
2. Performance and test requirements
Name the standard for each property and the limit you require. For most markets, EN 14411 or ISO 13006 sets the baseline for porcelain tiles, with ANSI A137.1 or ANSI A137.3 in the US. Then list the tests:
- Water absorption to ISO 10545-3.
- Breaking strength and modulus of rupture to ISO 10545-4, for the exact thickness.
- Chemical and stain resistance to ISO 10545-13 and ISO 10545-14.
- Thermal shock to ISO 10545-9, and frost resistance to ISO 10545-12 for outdoor use.
- Abrasion to ISO 10545-7 for glazed, or ISO 10545-6 for unglazed slabs.
- Slip resistance to the method your market uses, for floor slabs.
- Any food-contact or market certification you need.
Slip resistance and test type
Slip resistance methods are covered in floor tile slip resistance. State whether tests are a factory type test, a test on your production lot, or both.
3. Tolerances and grade
- Maximum centre curvature, edge curvature and warpage in millimetres, measured to ISO 10545-2.
- Squareness and edge straightness limits.
- The grade, with the factory's written grade definition attached, including allowed defects per slab.
- Shade rule: one batch, one shade and one calibre per design, matching the signed master sample.
- For book-match: every set complete, in sequence and matched.
4. Packing and labelling
- Packing type, such as A-frame or crate, with materials, face and corner protection and strapping.
- Slabs per frame or crate, and maximum gross weight per frame or crate.
- ISPM 15 treatment and marking for all solid wood.
- Labels showing design, size, thickness, grade, shade, calibre, batch, slab count, gross weight and set numbers.
- Container loading plan, with bracing and lashing.
5. Samples, inspection and acceptance
- Signed master samples, one kept by each party.
- Pre-shipment inspection before packing is sealed, with the sampling plan and defect classes stated.
- Supervised loading with photos.
- The breakage allowance, the evidence required for a claim, and how replacements are supplied.
- Documents to be supplied: test reports, installation and care guides, and any certificates.
The inspection itself
The inspection itself is described in inspecting slabs before loading.
Common mistakes
- Writing "first quality" or "export quality" without attaching the definition.
- Giving a thickness without a tolerance.
- Accepting a test report for a different thickness or finish.
- Leaving packing to the factory's standard without seeing it.
Next step
We draft slab specifications with you, agree them with the factory before production and inspect against them before loading. To start yours, book a free sourcing review.