Why stainless panels
oil-can, and what
stops it

What oil-canning actually is

The panel is not bent. It is a thin plate held at its edges, and when it warms or is loaded it buckles outwards between the fixings. The surface moves by a fraction of a millimetre, and the reflection breaks into a wave.

It is almost invisible in diffuse light and unmissable under a grazing light or a mirror finish. That is why it gets discovered after handover, usually by the person who cleans the wall.

Cause one: thickness

A 0.8 mm panel on a 600 mm frame span will oil-can. A 1.5 mm panel on the same span will not. Going from 1.2 to 1.5 mm is usually cheaper than adding a frame member, and it solves the reflection rather than hiding it.

Thicker is not automatically better: above 3.0 mm you are paying for weight and formability you do not need on a wall.

Cause two: return depth

A flat sheet is a membrane. A sheet with a folded return on four sides is a tray, and a tray is many times stiffer for the same thickness. A 25 mm return on all four edges is the single lowest-cost stiffener available.

This is also why we fold rather than just cut. A panel with no return is relying entirely on its frame to stay flat.

Cause three: frame spacing

Frame members are usually set by the stud layout rather than by the panel. When the spacing is 600 mm instead of 400 mm, the panel between them has to work harder.

Pulling the frame in is more expensive than thickening the panel, so it is usually the last option — but on a mirror finish it is sometimes the only one that works.

The lowest-cost fix, in order

1. Add a folded return on all four edges — usually free within the existing price
2. Go from 1.2 to 1.5 mm on the same frame
3. Add one mid-rail on spans over 1.2 m
4. Reduce frame spacing to 400 mm

Ask for the panel to be checked on a straight edge under raking light before packing. A wave that is visible on our floor is a wave we can still fix.