Powder coating

Powder coating, in the order it runs.

Metal parts in Jack's programs — brackets, frames, cabinets, panels and rails — are finished on powder-coating lines at his partner factories. These photos are from those lines; tooling for the parts themselves is on the engineering and tooling page. A part is hung, cleaned, dried, sprayed, cured and inspected, in that order.

**Small parts on a rack.** Dozens of small brackets hang on one rack while an electrostatic gun lays down orange powder.

The six steps

Hang, clean, dry, spray, cure, inspect.

The order matters: powder only holds as well as the metal under it was cleaned.

HangParts are racked so they do not touch.
PretreatmentDegrease, rinse and phosphate-coat the bare metal.
DryWater is blown off before any powder goes on.
SprayAn electrostatic gun coats the part.
CureThe oven melts the powder and crosslinks the film.
InspectCooled, checked and packed.

Step 01 · Hang

Racked so no two parts touch.

Parts go on racks or hooks with space between them, so the powder reaches every face and nothing fuses together in the oven.

Parts are degreased, rinsed, and phosphate-coated before any powder is applied — **Pretreatment tanks.** A row of chemical tanks under overhead exhaust: this is cleaning chemistry, not paint.

Step 02 · Pretreatment

Cleaned before anything is sprayed.

Parts are degreased, rinsed and phosphate-coated before any powder is applied. This is why the coating stays on: adhesion starts with the metal, not the paint.

Step 03 · Dry. Water is blown off before powder, so nothing is trapped under the film.

Step 04 · Spray

Large frames by hand, small parts by the rack.

An electrostatic gun charges the powder so it wraps onto the grounded part. Large frames and cabinets are hand-sprayed; small parts run in dense racks.

**Manual spray, large cabinet.** An operator in a full suit sprays powder onto a large metal cabinet inside the booth.

**In-line spray tunnel.** Hanging hubs move through a narrow spray tunnel while operators coat both sides.

**Sheet-metal panel in the booth.** A punched panel receives green powder, with even coverage on the cutouts and edges. An uncoated part hangs beside it.

**Mixed parts, one line.** Discs, a cylinder and a bar hang from the line as orange powder is applied.

**Tubular bracket, yellow finish.** A bent-tube bracket is coated yellow while other hanging parts wait behind.

**Structural steel.** The gun and respirator in front of a yellow steel platform and rail.

**The line, not just the gun.** An automated overhead loop carries large panels into the spray and oven tunnel.

Steps 05 and 06 · Cure and inspect

Baked on, then checked.

The oven melts the powder and crosslinks it into a hard film. After the parts cool they are checked for film thickness, adhesion and color match, then packed. The two checks worth writing into your order, film thickness and adhesion, are explained in what powder coating is and how to specify it.

How Jack's line watch inspects a lot ›

Large flat panels hang with an even gray film, ready to inspect — **Panels after coating.** Large flat panels hang with an even gray film: uniform color, no drips.

Have a metal part that needs a finish?

Send a drawing or a photo. Jack reads it himself and tells you plainly what the finish, the line and the inspection involve.

Ask for time with Jack

From the notes

Written down, with sources.

What is powder coating? A buyer's guide to the finish
What powder coating is, how a line runs, epoxy vs polyester powders, and the thickness and adhesion checks to write into your purchase order before a run.