Putting a mirror-like chrome finish on a wooden pinewood derby car is one of the most challenging painting projects. This page shows which paint works best and which techniques gets the most out of it. (For a video of everything on this page, please scroll down to the link at the end.)
Testing 16 different types of metallic spray paints, all of which claimed to produce a mirror-like finish, only one stood out as delivering on this promise: Spaz Stix Ultimate Mirror Chrome.
Available in high end hobby shops and from Amazon.com, this product is comparatively expensive, $12.00 for a 5-ounce can. It's actually intended for spraying the insides of clear Lexan R/C car bodies. However, with a little care it can also produce a bright metallic chrome finish on exterior surfaces. Its biggest drawback is that after testing many brands and types of clear coats, I have yet to find one that doesn't dull the shine and change the color of Spaz Stix Mirror Chrome. However, it has to be said that this is true for all the other paints as well.
Sprayed thick, Spaz Stix Mirror Chrome is at best semi-gloss, producing a finish that looks like buffed aluminum. However, sprayed in many extremely light fog coats, the individual droplets spread out and, if the undercoating is glassy smooth, create a shiny, mirror-like surface that looks as much like true chrome as is possible from spray paint.
The first step then is to create a smooth, glossy base on which to spray Spaz Stix.
Start by covering the car with a good pore filler so that areas showing end grain don't leave dimples in the final finish and differing side grains don't leave stripes. I've found that Magicoat works the best. It's a thick, creaming filler designed for Styrofoam and is available from Michael's craft stores. Spread on two thick coats, allowing four hours drying between them.
Sand smooth with a soft cloth-backed sandpaper. I prefer Micromesh 1500. It works very slowly, which provides a lot of control. Do not sand all the way down to the wood. The car should still be covered in white sealer, but look shiny smooth and even.
To make painting easier, I drill a small hole in the base of the pinewood derby car just in front of the main weight, being careful not to drill all the way through, then screw in a 12-inch dowel fitted with a reversed screw in the end.
This enables the car to turned any way desired to provide access to all surfaces. A heavy block of wood with a hole slightly larger than the dowel acts a a base to hold the dowel while the car is drying.
After testing
several gloss black spray paints, the one that produced the glossiest
surface with the fewest runs was Model Master Gloss Black spray paint.
Spray two light coats, waiting 20 minutes between each. This is trickier than it sounds because Model Master Gloss Black paint comes out in a very wide and heavy spray. After the car looks completely covered, follow in 20 minutes with a wet spray. This is a heavier spray where the paint is thick enough for the droplets to flow together to create a glassy smooth surface. It's tricky because if just a little too much paint gets sprayed in one area, it'll create a run. But this wet coat is essential because no matter how many light coats you put on, they will never create the glassy smooth base required for a mirror-like chrome look.
After this final coat, set the car aside and let it dry at least three days.
Assuming all went well, moving on to the chrome spray can be surprisingly difficult. There's something hauntingly elegant about the simplicity of a pinewood derby car with a perfect, glossy black finish. I always have to pause and reconvince myself that what I really want is a car that looks chrome plated.
Start by removing the paper label from the can of Spaz Stix and warming it in water as hot as possible from a tap, being careful to avoid getting water in the nozzle. Warming it increases the pressure in the can and produces a finer spray. After quickly drying the can and thoroughly shaking it, spray on ten extremely light fogging coats. These light coats are the key to creating a glassy finish. They should be so light it's hard to see the first two. You only need to wait a minute or two between coats.
After ten coats, the car should be completely covered and have a slightly dusty appearance.
Set it aside and let it dry at least 24 hours.
After it's thoroughly dry, a close look shows a surface covered in fine dust. These are flecks of paint that didn't spread out over the gloss black base coat.
Using a very soft, clean cloth, such as a microfiber lens cleaning cloth or an old, newly laundered T-shirt, lightly buff the surface of the car. I prefer using cotton gloves because if I need to handle the car and the paint isn't completely cured I won't leave fingerprints.
All the dust will wipe off easily, revealing a mirror-like metal chrome finish. And that's it!
The car
featured on this page is called Silver Bullet.
It's a remake of a car made many months ago without using the fog-coat technique with the result the finish didn't have the glass-sharp look I wanted. After another week to let the finsh completely harden, I found that I can handle it and not leave fingerprints that discolor the finish. An earlier car is a year old and the Spaz Stix Mirror Chrome looks as good as the day it was completed.
This is fortunate because as mentioned earlier, there are no clear coats that don't reduce the shine and change the color of Spaz Stix. This applies also to colored overcoats such as candy apple red. The following image shows how much the shine is reduced by attempting this:
The colored areas look okay, but they don't have the mirror-like reflectance of the uncoated areas.
The following video shows the entire process in live action.
Thanks for stopping by and I wish you the best of luck with your pinewood derby car!
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