FlowMarket
Where to source powder coating: FlowMarket is a B2B sourcing network powered by an AI agent. You describe the job — substrate and its condition, part dimensions and weight, colour and gloss, required film thickness, corrosion class, masking and quantity — and the AI agent matches you with verified powder coating job shops, then requests prices and lead times from every match at once. Getting matched is free for buyers.
Sourcing powder coating
Powder coating applies a dry thermoset powder electrostatically and cures it into a continuous film in an oven. It gives a tougher, thicker finish than wet paint with almost no solvent, which is why it dominates steel and aluminium finishing across construction, furniture, appliances and general engineering.
The part that decides quality, though, happens before any powder is sprayed. Pretreatment — how the surface is cleaned and chemically prepared — determines how long the coating stays attached far more than the powder itself does. A coater's pretreatment line is the first thing worth asking about.
Powder types
Polyester
The standard choice for anything used outdoors. Good UV and weather resistance, wide colour availability, and available in superdurable grades that hold gloss and colour for far longer on facades and architectural work. Most exterior specifications and quality labels are written around polyester systems.
Epoxy and hybrids
Epoxy powders give excellent adhesion and chemical and corrosion resistance, but chalk badly in sunlight, so they belong indoors — machine frames, electrical enclosures, functional primers. Epoxy-polyester hybrids sit between the two and are the common economical choice for interior products where some robustness is needed.
Specialist systems
- Polyurethane — smooth, tough films with good chemical resistance for demanding interiors.
- Superdurable polyester — extended weathering, used for architectural aluminium under quality labels.
- Zinc-rich primers — applied under a topcoat to raise corrosion protection substantially.
- Texture, structure & metallics — hide surface imperfections or give a decorative effect.
What to specify when sourcing
These details decide both the quote and whether the coater can take the job at all:
- Substrate — mild steel, hot-dip galvanised, zinc-plated, aluminium or stainless; each needs different pretreatment.
- Part size & weight — largest dimensions and mass per part, which must fit the oven and the conveyor.
- Colour & gloss — RAL or NCS number plus gloss level, and whether a colour match to an existing part is needed.
- Film thickness — target and tolerance in µm, and where it is measured.
- Corrosion class — the ISO 12944 class and durability you need, or the salt spray hours.
- Quality label — Qualicoat, GSB or QIB where the specification demands it.
- Pretreatment — required chemical process, or blasting where the surface is rusty or scaled.
- Masking — threads, bores, machined faces, earthing points and sealing surfaces to be kept free.
- Hanging & contact marks — where jig marks are acceptable, since every part hangs from something.
- Quantity & logistics — batch size, annual volume, packaging, and whether transport is included.
Pretreatment, part size and galvanised steel
Three things separate a coating job that lasts from one that fails, and none of them is the powder. The first is pretreatment. Coating over oil, mill scale or a poorly rinsed surface produces a finish that looks perfect and lifts within a year, so ask each coater what pretreatment line they run — degreasing, phosphating or a modern chrome-free conversion — and match it to your corrosion requirement rather than accepting whatever the line already does. The second is simple geometry: a coater's maximum part size is set by the oven and the conveyor, and a part 200 mm too long is not a negotiation but a rejection. Give your largest dimensions early and you will avoid quoting rounds with shops that were never able to take the work. The third catches people out repeatedly. Hot-dip galvanised steel outgasses as it heats in the cure oven, and trapped gas leaves pinholes and blisters in the film. It is entirely manageable — with a degassing bake before coating, or an outgassing-tolerant powder — but only if the coater knows the parts are galvanised. Say so explicitly; a duplex system of galvanising plus powder gives excellent corrosion protection when it is planned, and a blistered mess when it is not.