Sourcing screen protectors

The pencil hardness test drags a graded pencil lead across a coating at a defined angle and load, and reports the hardest grade that does not mark it. The grades run through the soft end and up to 9H, which is the top of that scale — it is a coating test, not a mineral one, and it says nothing about resistance to sand or to a key.

Because every product in the category claims 9H, the figure carries no information. A supplier who leads with it is quoting the industry's default sentence, and a buyer who compares suppliers on it is comparing nothing. It is also a claim you inherit once your brand is on the box.

Specify what varies instead. Glass type and thickness; whether it is chemically strengthened and to what; the film type for non-glass products; the adhesive system; the oleophobic coating and its abrasion requirement; the edge treatment; the printing or frame if there is one; and dimensional tolerance against the exact handset model.

If scratch resistance matters to your listing, define your own test — the abradant, the load, the number of cycles and the pass criterion — and have it run to your definition, exactly as with drop claims on cases. Your own test is defensible; a repeated industry phrase is not.

Transmittance and haze are real, measurable properties and are worth specifying if optical quality is part of your positioning. Ask for the measurement rather than an adjective.

The adhesive system decides most of the outcome. Full-surface adhesive behaves differently from edge-only adhesive: full adhesive avoids the rainbow effect and ghost touches but is less forgiving of dust during application; edge adhesive is easier to apply and can lift. Specify which, and specify the adhesive supplier and grade rather than "silicone adhesive".

Bubbles that appear later are an adhesive and cleanliness problem, not a user error. Ask what the factory does about dust — a clean room class, the packing sequence, whether the protector is packed adhesive-side protected — and check samples that have been shipped and stored rather than fresh from the line.

Case compatibility. A protector that is a fraction too wide or too thick stops a case closing, and a huge share of returns are this rather than a defect. Specify the case-friendly dimensions explicitly and test with the cases your customers actually use.

Curved-edge handsets are their own problem: adhesion at the curve, lifting, and a visible band at the edge. If you cover curved-screen models, treat them as a separate specification with their own sample approval, not as a size variant.

The application kit is part of the product. Dust removal stickers, an alignment frame, a wipe and instructions. An alignment frame turns a difficult product into an easy one and is the cheapest review improvement available in this category.

Trademarks in listings. Protectors are sold by handset model, and listings routinely use a handset maker's trademarks to say which model they fit. Referential use to describe compatibility and use that implies endorsement or origin are different things, and the line differs by market. Take advice for your market on how to word compatibility rather than copying what everybody else does.

Printed and coated designs. Any artwork, character or pattern on a protector or its packaging carries the same licensing question as it does on a case, and a factory offering a catalogue of designs is not offering evidence that anybody holds a licence.

Counterfeit packaging. Protectors are frequently sold in packaging imitating a brand's trade dress, which is a different order of problem and an ordinary reason for a seizure.

And the commercial one, which decides whether the category works at all: protectors are cut per handset model, handset ranges change every year, and stock for a discontinued model is worth nothing. Model coverage and reorder discipline decide the outcome far more than unit price does.

It is also why this marketplace does not list screen protectors. Like cases, the leaf is switched off deliberately — a factory-only marketplace cannot verify a licence chain it never saw, and not listing is the honest answer rather than listing with a disclaimer.

Business licence and business scope (经营范围) first. Then ask what is done in-house — cutting, coating, adhesive lamination and packing are frequently separate companies, and the coating is where quality varies most.

The specification: material and thickness; strengthening; adhesive system with supplier and grade; oleophobic coating with an abrasion requirement; edge treatment; transmittance and haze if claimed; case-friendly dimensions; the application kit; the packing method; and dimensional tolerance verified against a real handset of the exact model.

Sample against real handsets, not drawings, and with the cases you sell. Then age samples: rub the oleophobic coating to a defined cycle count, leave one applied in a warm humid environment for weeks and check for lifting, and test touch behaviour near the edges on a real device.

Check shipped samples rather than fresh ones. Adhesive contamination, edge damage and packaging marking all happen in transit and storage, and a protector inspected at the factory is not the protector a customer opens.

Every supplier listed on this site is a manufacturer, and the registered-scope check is one of the things confirmed before a listing goes live — but screen protectors are not listed at all, and that is deliberate.