Powder coat on fast food chairs: the four numbers that matter

Thickness, and why 60 microns is a floor

Powder coat on tubular steel frames runs 60 to 80 microns dry film. Below 60 the coat follows the mill scale and the weld texture rather than covering them, and the first place it fails is the weld toe, where the surface is roughest and the coat ends up thinnest. That is also the place nobody looks until rust appears from underneath.

Above 100 microns the coat becomes brittle and chips rather than flexing when a chair leg is knocked against a table. So the specification is a band rather than a minimum: 60 to 80 microns on a steel frame, measured on the finished part with a gauge rather than on a flat test panel the line ran for the record.

Salt spray hours are the number quoted at this point, and it is worth knowing what they measure. The salt spray result rates a flat panel in a cabinet, not a welded chair in a room, and two coats quoting the same hours can behave differently once the panel is bent into a frame. Treat the hours as a comparison between two powders, never as a forecast of service life.

Ask where it is measured. The frame is a tube, a weld and a bend, and the coat builds on the outside of a bend and thins on the inside of it. Three readings per chair on the exposed tubes is enough to catch a line drifting.

Pre-treatment decides more than the powder

Three-stage pre-treatment is degrease, rinse and dry. Five-stage adds a conversion coating that bonds the powder to the steel chemically. On a fast food chair, which is wiped daily with sanitiser and knocked against tables, the conversion coating is what stops rust creeping out from a chip and lifting the coat around it.

This is where cheap frames hide, because the powder is the same product in both cases and the line it was applied on is not. Coat applied over a badly degreased frame will lift in sheets within a year, and no thickness reading will predict it. Ask what the pre-treatment sequence is, not just what the powder is called.

Curing, and the parts that miss it

Curing at 180 to 200 degrees Celsius for the time the powder datasheet states gives full cross-linking. Under-cured coat looks fine and marks white when scraped with a fingernail. Over-cured coat yellows, which is invisible on black and obvious on white or light grey, so the same line fault shows on one customer's order and not on another's.

The parts that miss the cure are the thick ones: a cast base, a heavy bracket, a welded foot. They come up to temperature later than the tube they are welded to, and a line running a fixed cycle sends them out under-cured. Ask how the cure is verified on heavy sections, since that question separates a factory from a trader.

Colour control on a repeat order

Colour is matched to a RAL or Pantone reference and checked against an approved panel under daylight. Workshop light flatters a coat and hides a shift of two or three units, which is exactly the shift that makes a top-up order look like a different product three years later, when nothing can be returned.

Where the room already has furniture, send a physical sample rather than a code. custom fast food furniture is often a colour question rather than a shape question, and a photographed sample is worth nothing for matching. Keep one approved panel in the project file; it is the only reference that survives a change of staff.

Writing it on the order

Put four lines on the purchase order: powder type and gloss level, dry film thickness band, pre-treatment sequence and the cure schedule. Add a fifth for the colour reference and the panel that was approved against it, with the date of approval.

fast food furniture quality then has something to check against at goods-in, and a rejected batch carries a reason rather than an opinion. commercial fast food seating lives longer on that page of paper than on any photograph of a finished room, because the photograph cannot show a forty micron coat, and nobody photographs a weld toe until it has rusted.

What buyers ask about this

Is powder coat better than chrome on a QSR chair?

It hides scratches better and is repairable with a touch-up pen. Chrome shows every mark and cannot be repaired locally.

Can a chipped frame be touched up?

Yes, with matched touch-up paint, and it should be done the week it happens rather than at the next refit.

Does gloss level matter for cleaning?

Matte hides fingerprints and shows scuffs less. Gloss wipes clean faster. Most quick service rooms choose matte for the frame.

Which frame carries this finish?

fast food chairs in the range are powder coated over a five-stage line, and fast food chair manufacturer documents go out with the batch where a project needs them.

Related notes

What a 150 kg chair load test proves, and what it does not

Cleaning chemicals that quietly ruin quick service finishes

Colour matching powder coat to a brand guide, without surprises