Powdercoat Refinishing


A couple of years ago I bought a fairly gutted Asteroids machine for $50. It had been sitting in a damp storage area and the bulk of its metal parts had been damaged by rust and corrosion. Since the sides of the machine were in quite good condition (and since I already had the innards of another Asteroids that was dry-rotted beyond salvage) I decided that this one would be a good candidate to restore.

I always like seeing those "before and after" type home restoration programs on TV, so I thought it would be fun to document the restoration process piece by piece as a record of the machine's progress and as a help guide to others. This first part will describe refinishing the metal marquee holders on the top of the machine.

Atari finished many of the metal pieces on their classic arcade games with a technique known as powder-coating. Powdercoating is a process by which a tough (usually plastic based) finish is actually baked onto the metal. It is more durable than most painting processes and generates that fine-grained "orange-peel" like surface unlike a spray-on paint would..

Having previously refinished parts using multiple coatings of "Rustoleum Matte Black" (now just "Rustoleum Flat Black" is available) spray point I was familiar with its overall good results, but wanted to get closer to that classic Atari texture. A little bit of searching revealed that home powder-coating systems were available and affordable ($99 for the unit I purchased).

I proceeded to buy a powdercoat system from Harbor Freight (www.harborfreight.com) as well as a pressurized sand-blaster. (Total damage-- right around $200)

Powdercoating works by electrically charging a fine powder of colored plastic to "stick" it to a grounded piece of metal. (It's similar to how dust sticks to a TV screen.) The powdercoating machine generates a high-voltage which charges the particles of plastic as they're blown out of the "gun" by compressed air. Once the plastic powder is stuck to the metal the metal is heated and the plastic baked on.

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I decided to start my project with the top piece of the metal marquee holder off of the Asteroids machine. ~20 years of damp Pacific Northwest weather had caused it to rust and bubble the old finish off. The metal was moderately pitted and generally in poor shape.

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I loaded up the "abrasive blaster" with dry river sand (about $1.50 at Home Depot) and proceeded to make the largest artificial dust cloud known to man while blasting the old paint off the metal. (Note to self: next time buy some kind of "washed" sand (like for a sandbox) or get some "real" sand-blasting media instead!)

Mess aside, the sandblasting worked pretty well and left me with some reasonably clean metal. I'd have to use a more abrasive/smaller media to get all the last traces of rust off, but for now this works for me.

Some Naval Jelly was used to neutralize the remaining deep-rooted rust and then the piece was rinsed/brushed with acetone to get any remaining contaminants or oils off of it. (Use a lint-free cloth or wire-brush when rinsing away the dust and oil-- getting lint all over the metal will mess up the finish!)

Using the powdercoating machine is pretty simple. An alligator-clip is attached to the metal to provide a ground path, a 10-15 PSI dry air source is connected to the gun and when you're ready you press a foot-switch down and pull the trigger on the powdercoating gun. A semi-focused cloud of plastic dust (a LOT like photocopier toner methinks!) coats the metal and sticks to it rather well. Wear a GOOD respirator and work in a well ventilated area; the plastic dust is ultra-fine! Don't work near open flame either lest your arcade game refinishing project end up in a demonstration of why grain-elevators explode...

With the powder on the piece, you need to transport it to an oven for baking. (Without brushing any off!) Ideally this would be a large industrial oven, but an old home oven will work well too. (They say not to use an oven that's still used for food-- apparently the plastic outgasses some nasty stuff.) I didn't have an oven available, so I improvised and put the piece in an old patio grill and used an electric heating element from a stove to heat it up. The plastic seems to melt at about ~200F and the instructions said to bake it for 15 minutes at 400F after it melts to cure it. I used an infra-red non-contact thermometer to check the temperature. I moved the heating element around to get an even "bake" across the metal.

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Ta-da! One powdercoated marquee holder (and all for less than ~$300 or so in tools ;-) ! The powder that I used has a very glossy finish (almost like the enamel in a sink), but it yielded very good results. I'll probably try to find a more matte finish sometime, but Asteroids will just have to be a little "shiny". It looks good though. You can see in the close-up the slightly textured (but smooth and sealed) finish.

The powder has some nice properties once baked-- it's completely waterproof (essentially just a sheet of plastic sticking to the metal); it can be applied in multiple coats (which will just melt together); and if a piece of crud gets on during baking you can pick it off and the plastic will flow together an cover the holiday (unlike paint).

All in all a pretty successful first attempt! Refinishing the game's control panel this way will be... Interesting. Not sure how to do something quite so large (an Asteroids control panel is MASSIVE!) without a big oven. On the other hand, the powdercoat seems to be very forgiving when you work in sections, so just heating a smaller area at a time might work OK.

Some other useful powdercoating links:

http://www.hotcoat.com

http://www.harborfreight.com

http://www.eastwoodcompany.com

Update:

This summer I did some more powdercoating using Eastwood's "Satin Black". It's a nice 'non-gloss' finish that looks good on arcade parts. The technique remains the same as above, just using a different powder at the end of the process. Here's a few shots of a coin door I refinished/refurbished:

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Updated: 6/19/2003, 1/15/2005


2005, Clayton Cowgill info@multigame.com