Stop the packing and ask for three records from this shipment. First, a test bond made now: glue a piece cut from a panel in this container to a piece of the same wall substrate the project uses, leave it, pull it apart, and photograph the two torn faces. Second, the back of a panel from this lot, photographed as it ships, with the answer on what the back needs before bonding. Third, the adhesive itself: the label on the tubs in this order, the batch, and how they were stored on the way. A compatibility chart, a showroom wall that is still up, and a promise to use more glue do not release the rest.

Read the failure face before anything is re-glued

When a panel comes off a wall, the evidence is on the two surfaces that parted. Look at where the adhesive ended up. If the glue is stuck to the wall and the back of the panel is clean, the joint failed at the panel, and the question is what is on that back: dust, a release agent from the moulding or coating line, a film, or a texture the adhesive cannot key into. If the glue is stuck to the panel and the wall is clean, the joint failed at the substrate, which is a project problem with primer and surface, not a panel problem. If the adhesive itself has torn through the middle, the product or the way it was applied is the question.

Those three outcomes lead to three different fixes, and they are told apart by one photograph. So when a panel peels, do not let the installer clean it up and re-glue it. Photograph both faces, keep the panel, and write the date and the room on it. A panel that has been cleaned and stuck back on the wall is a panel that can no longer tell anyone why it failed.

Photograph the back of a panel from this lot

The back is the surface that never appears in a catalogue and rarely appears in a sample room. Ask for a panel from this container turned over, photographed flat, with a light raking across it so the texture and any film show. Then compare that photograph with the back of the sample panel you approved. If the sample back was smooth and this lot is glossy, or the sample was dusted and this lot arrives with a chalky surface, the bonding surface changed without anyone deciding to change it.

Ask, in writing, what the back needs before adhesive goes on it. Some panels are bonded straight from the crate, some need a wipe with a solvent, some need a light abrasion, and some need a primer that the factory recommends for its own back surface. The general reference on adhesives makes the point that surface preparation is what makes a bond reproducible, which is the reason this step belongs in the instruction sheet rather than in the fitter’s habits. Write the answer into the order, because the next delivery will be fitted by a different crew.

Identify the adhesive that shipped with this lot

Two tubs that look the same can behave differently, so ask for the label on the containers that came with this order, not the brochure for the product family. Photograph the label, note the batch, and ask whether the batch is the one the sample wall was built with. If the batch changed, the showroom wall is no longer evidence about this shipment, and the test bond is the only thing that is.

Ask about storage as well. Adhesive that has frozen in an unheated container or baked in a summer port can arrive looking normal and behaving differently, and the tub gives no sign of it. A factory that answers with the storage conditions and the dates the tubs were filled is answering a real question. A factory that answers with a datasheet is answering a question about a product that may not be in your cartons.

Then match the adhesive to the job. The ranges the site carries, listed under construction adhesives and auxiliary materials, are not interchangeable between a lightweight decorative panel and a heavier board, and the wall behind them decides part of the answer too. Get the recommendation in writing for the panel and the substrate in this project, and use the same product on the test bond so that the test means something.

The wall is half of the joint

A bond is made of three things: the panel back, the adhesive, and the wall. The third one is the one the factory never sees, and it is where a surprising share of peel failures start. A dusty block wall, a painted surface, a sealed or glossy plaster, a wall that was never primed, or a wall that has been damp will all release a panel that was perfectly made. Ask for the substrate details from the project, and ask the factory to state which of those conditions their recommended method covers.

Then photograph the wall where a panel came off, in the same set as the panel faces. The two photographs together are what let a technician say whether the panel or the wall failed, and that answer decides who pays for the fix. Without the wall photograph, every failure looks like a panel failure, and the conversation never reaches the real cause.

If the project uses a mechanical method somewhere, such as clips or battens rather than a bonded face, keep that decision separate. The site sets out the difference between the two approaches for commercial wall panel projects, and a project that has to survive a bad substrate is sometimes better served by a mechanical fixing than by a better adhesive. That is a design decision, and it should be made before the panels are packed rather than after the first ones peel.

What to do with the panels you already have

Do not install the rest while the question is open. Check one installed panel by hand, in a place where a release would be visible, and photograph what you see. Then sort the unopened cartons the same way you would sort any other batch: panels kept for the rooms that are already finished, panels held for the test bond, and one panel kept aside as the record with its carton number. The test bond should be made with a piece from the same carton as the panels that failed, and with the substrate that failed, because mixing cartons in one test is how a bad batch passes.

If the peel is at the panel back, that is a factory question, and the fix has to come with the back preparation written down and the adhesive matched to it. If the peel is at the wall, the fix belongs to the site: priming, cleaning, and possibly a mechanical fixing for the affected areas. Keep the two cases apart in your claim, and do not let a site problem be answered with a new box of adhesive, or a panel problem be answered with a primer the wall did not need.

This is not the bow record from the last check

Panels that arrive bowed and panels that come off a wall are two different complaints, and the records do not substitute for each other. The check on a bowed panel before packing looks at the shape of the board on a flat surface. This one looks at the back surface, the adhesive and the wall. A flat panel can still release, and a bowed panel can still bond, so when you write the hold, say which problem you are raising and keep the photographs in separate sets.

If both are present, send both sets with their own carton numbers. A factory that is asked about two problems in one paragraph will answer the cheaper one and pack the rest while the other is still being read.

Write the hold the same day

Send one message to the person who can stop the line. Name the order and the panel. Say the showroom wall held and panels from this container are peeling, and state the hold in one sentence: no more panels packed until you have the three records from this lot. Name them. First, a test bond made with a piece from this container and the project substrate, pulled apart, with both torn faces photographed side by side. Second, the back of a panel from this lot photographed as it ships, with the written instruction on what the back needs before bonding. Third, the adhesive label and batch for the tubs in this order, with how they were stored and the confirmation that the product is the one recommended for this panel and this wall.

A release is your note that the test bond holds and fails at the adhesive rather than at either surface, that the back preparation is in writing, and that the adhesive in the cartons matches the one in the test. A compatibility chart, a showroom wall, and an offer to send more glue do not release the hold.

Keep the test pieces, the peeled panel, the wall photograph and the carton number in the order folder. The next container will be bonded by a different crew on a different wall, and the pieces from this lot are what make the next answer short.