The common ACP and aluminium panel defects are oil-canning (visible waviness), delamination (skin lifting from the core), colour and gloss mismatch between batches, edge and corner damage, and coating flaws like scratches or chalking. Most are handling, grade or batch problems, not deep manufacturing faults, and all are catchable on delivery if you know what to look for. Here is how to spot each before panels go on the building.
Oil-canning and flatness
Oil-canning is visible waviness across a panel face, worst on thin skins and large flat areas. Check panels flat under raking light before install — a wavy sample only gets worse on a facade. The usual cause is too thin a skin (0.21mm vs 0.50mm) or poor handling. Real facade ACP at 0.50mm skins reads flat; if a sample does not, reject the grade.
Delamination
Delamination is the aluminium skin lifting or bubbling away from the core — a bonding failure, and a serious one. Look for edge lifting, blisters, or a hollow sound when tapped. It shows up at cut edges and after heat. A properly bonded panel stays solid; any delamination is grounds to reject, as it worsens with temperature cycling.
Colour and gloss mismatch
Panels from different coating batches of the “same” RAL can differ, and it shows on a facade. Check delivered panels against the approved control sample and against each other under daylight, especially gloss and metallic finishes. Order the whole job from one batch to avoid it; on delivery, hold any panels that do not match the reference.
Edge damage and coating flaws
Denting, scratched coating, and crushed corners are handling damage — check edges and corners as panels are unpacked, before the film comes off. Coating flaws include scratches, pinholes, chalking (a dull powder, meaning wrong/old coating) and uneven gloss. Keep protective film on until install to prevent site scratches, and inspect against the spec and control sample.
Frequently asked questions
What is oil-canning in ACP? Visible waviness across the panel face, usually from too thin a skin or poor handling. Check flatness under raking light before install.
What is delamination? The aluminium skin lifting or bubbling from the core — a bonding failure. Look for edge lifting, blisters or a hollow tap; it is grounds to reject.
How do I check colour consistency? Compare delivered panels against the approved control sample and each other under daylight; order the whole job from one coating batch.
When should I inspect for damage? As panels are unpacked, before removing the protective film — check edges, corners and coating against the spec and control sample.
Related: ACP facade panel thickness · third-party pre-shipment inspection · ACP sample & mock-up approval.
Talk to the factory: GSM BuildTech (Beijing Guanshimao Technology Co., Ltd.) makes FR aluminium composite panels, PVDF aluminium coil and insulated aluminium panels in Tianjin, China, and welcomes factory audits, samples, mock-ups and third-party inspection. Email sales@insulatedaluminumroof.com or WhatsApp +86 155 2274 6824. See the technical reference & FAQ.
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