An appliance maker in Poland sent us a two-line email last spring: their notified body had rejected a technical file because the acrylic UL certification named a grade that did not appear on any card at the thickness used. The panel was real, the test was real, the paperwork was not.
What acrylic UL certification actually consists of
Three documents do the work: the yellow card entry, a certificate of compliance referencing that entry, and the test report behind it. Each has a job. The card proves the material and thickness are listed; the certificate ties a shipment to the listing; the report shows what was measured and how.
A website badge proves none of them. It is a marketing asset, and it is the first thing a reviewer discards.
The thickness line is where claims break
Cards list discrete thicknesses, often 1.5, 2.0, 3.0 and 4.5 mm for a given grade. Buyers routinely specify 5 mm and inherit a claim that stops at 4.5 mm. Read the card as a table, not as a headline.
UL 94, UL 746 and why the numbers confuse people
UL 94 answers a burning question: how the material behaves in a small flame, expressed as HB, V-2, V-1 or V-0. UL 746 answers a longer-term materials question covering electrical, thermal and mechanical performance. A datasheet that says UL 94 V-0 has told you about flammability and nothing else.
For an enclosure that will sit near a transformer, both matter, and the technical file needs the second one. Our UL94 guide for flame-retardant sheet sets out which rating covers which duty.
Ten minutes to check a supplier claim
- Ask for the yellow card as a file, not a screenshot of a logo
- Read the material designation and compare it to the invoice description
- Confirm the thickness you buy appears in the listed range
- Confirm the colour; many listings cover clear only
- Check the card holder name against the company issuing the certificate
- Ask which test laboratory produced the underlying report
If any of those six cannot be produced, the claim is marketing. That is not an accusation of fraud; it is simply the difference between a test that happened once and a listing that is maintained.
Where certification changes the price
Flame-retardant acrylic costs more because the formulation carries additives and the listing carries surveillance. On a 5 mm clear panel the premium is typically fifteen to twenty-five per cent against general purpose, and most of it is compliance overhead rather than polymer.
Buyers who need the paper should budget for it early. Buyers who do not need it should stop paying for it, and specify general purpose instead.
Keeping the file current
Cards are revised. A grade that was listed at 3.0 mm last year may be listed at 2.8 and 3.2 this year after a reformulation. Ask for the revision date on every repeat order, and keep the version in the technical file so that a future audit can reconstruct what was shipped.
Thickness and tolerance wording belongs in the same appendix; this note on thickness tolerance shows how to write it so the compliance claim and the dimensional claim do not contradict each other.
For a copy of our yellow card at the thickness you need, write to oversales@rpplexiglass.com with the grade, thickness and end product.
Frequently Asked Questions
Is UL 94 the same as UL certification?
No. UL 94 is a flammability test method with a rating such as HB, V-2 or V-0. UL certification is a follow-up service programme where the material appears on a yellow card at defined thicknesses. A V-0 claim without a card is a test result, not a listing.
Does the rating apply to every thickness?
It applies to the thicknesses tested and listed. A grade listed at 1.5 and 3.0 mm is not automatically compliant at 5 mm, and using it there removes the basis for the claim in a safety submission.
What should a certificate of compliance name?
The material designation, the colour, the thickness or thickness range, the standard, and the file or card reference. Certificates that name only the supplier and the word flame retardant are not usable in a technical file.