DIY Powder Coating

I was at a show last week and saw several trade stands selling DIY powder coating kits. I guess it can be baked in a domestic oven but it all sounds a bit dodgy!

Has anyone tried this at home and had success?

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What ever they call it, it is plastic coating and the quickest way get the item really rusty!

John Saunders on NYCCNC has used this kind of system and seemed quite happy with it.

Never used it myself but in a former job we used a lot of it (Trimite products mainly) - proper production system for coating sheet metal components.

Murray

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Powder coating is not plastic coating. (unless the DIY version is)

You must be thinking of something else.

Nick

My son-in-law runs a metal fabrication business (in Western Australia) and powder coats his products. He made the oven and I helped with the control circuit. He uses Dulux Powder Coating products. An internet search "Dulux powder coating" will find information about temperatures and times for baking - about 190c and 20 or 30 minutes from memory. He uses a commercial powder coating gun and booth.

Baking is easy. Applying the product is a bit more difficult, but someone with a bit of electrical engineering knowledge should be able to make a gun setup. Maybe after I retire I might experiment, if I get time!

Regards,

Alan.

could you please explain, i have been getting parts powder coated for years without any rust issues.regards gary

Powder coating is either polyester or polyurethane based powder which are plastics. If you chip, crack of pierce the coating, moisture will get under the coating and corrode like crazy.

Manufacturers use it as because it is a cheap finish and it looks very good when it leaves the factory.

I used to run a fabrication company and we only ever powder coated products after they had been galvanised. If the customer refused to pay for galvanising we turn the job down. The best finish for steel is a good coat of oil based paint.

You can see powder coating peeling off everything from garden furniture to mini diggers.

I set a simple system to powder coat at just the ends of tools so I had a chance of finding them in the grass... only needs a sniff of air. Powder from eBay. Heat with a torch to about blue tempering colour. Bottom has a pad of scotchbright and the (trimmed) top of the cocoa container with a grid of small holes.

Seen plenty of rubbish powder coat jobs pushing, peeling and cracking away to hold water and promote rust just as vintage engineer says. Not anything like as much of a problem as it used to be tho'. Back in the 1970s and 1980s it wasn't uncommon to see jobs with adhesion between coat and substrate being little better than heat shrink tubing. Properly done modern efforts are getting up to the standards of old style formaldehyde based stove enamelling which I've known sandblasters to just give up on as it proved virtually un-shiftable in reasonable time.

Spraying powder onto a cold substrate always seemed wrong to me. Would have thought a warm to hot substrate would promote better adhesion. Not hot enough to cure but hot enough to ensure that it rapidly comes up to melting / curing temperature at the interface during the process. Seems to me that if the substrate is cold the coating is likely to cure round it rather than sticking to it as, with external heat, the curing process surely proceeds from outside to inside.

Clive.

Back in the 70s, some of my G.P.O. Engineering colleagues got hold of some powder coating powder from somewhere in Slough (I.C.I. ?) They applied it by heating their pliers in the oven in the tea room, then dunking it in the powder, which stuck quite nicely, then suspended them in the oven from a piece of wire. It seemed to be satisfactory.

Maurice

The continuous process Trimite powder coat line we used had an electrostatic charge to get the powder to stick to the metal, then it went through an infrared oven to bake (melt) the plastic to the metal.

The metal we used was either aluminium or steel - these were all folded sheet metal parts, CNC punch and fold. The aluminium was chromate passivated and generally was linished whether powder coated or not. I can't imagine the stuff ever peeling off - that must have been a different material and process.

The process John Saunders uses seems to be broadly the same I describe but on a DIY scale - electrostatic gun and electric oven. I wouldn't mind getting something like that myself.

Murray

Some processes are indeed just a plastic coating but some are not, for example epoxy/acrylic fusion coatings. I guess you get what you pay for.

I had the swinging arm on my Divvy powder coated 17 years ago, still no signs of rust.