How to Build a Paint Dryer

by Chuck Davenport

[Ed. note: This article was originally published in the November/December 1994 issue of the IPMS Journal. Chuck has given permission to reproduce it here. This article is just a taste of what you get in the excellent magazine of the IPMS/USA. If you're not a member, perhaps you might consider joining. Check out the IPMS web site at:]

...Apply decal set and let dry for a day...spray on four wet coats of paint and allow the paint to cure for a week... Forget this drill. I want to complete a model in less time than it took to paint the Sistine Chapel, but everything takes so long to dry or cure. Not so, said Pat Covert who related that fellow car modeler Bob Downey from Atlanta was using a food dehydrator to drastically reduce drying times -- from weeks to days (ed. note: even hours) in some cases.

Photo 1
Remembering a similar concept described in FSM I decided to raid the spare parts bin (John Noack will tell you I never throw anything away) and improve on the basic concept. Dehydrators work on the principle of heat-generated convection currents. I decided to build a forced-air device. The dryer sits to the right of my table/spray booth (photo 1). The heart of the system (photo 2) is a homemade heater core attached to a polyethylene storage container that I purchased at Wal-Mart for $5.

Figure 1 - General Assembly

The heater core is thin sheet aluminum 10" x 12" x 8 1/2" (totally arbitrary dimensions that can be altered to suit your needs)

Photo 2
pop-riveted together using a Wal-Mart brand hand riveter. Nothing fancier than tin snips and a couple of clamps was required to cut and bend the aluminum. The top and bottom are 1/4" masonite with 3" holes drilled for air travel. Heat is supplied by a 100 watt bulb mounted on a $0.96 bracket, again, purchased at Wal-Mart (photo 2). A hand-formed sheet aluminum manifold distributes heat and protects the upper sheet of masonite from burning (photo 2). Air is forced with a computer cabinet circulating fan connected to a switch (both from the spares box) (photo 2). Figure 2 illustrates the wiring diagram.

Figure 2 - Wiring diagram

Photo 4
Air conditioner filter foam attached to the base with Elmer's glue, mounted to the fan, and fastened to the polyethylen box prevent dust from marring the finish (photos 2 and 4).

Photo 5
The top of the box was modified to control airflow and, therefore, temperature by drilling a 1 1/2" diameter hole and capping it with a sheet aluminum vent pop-riveted to the top, off-center from the hole (photo 5). Figure 3 details the construction.

Figure 3 - Exhaust vent

Photo 6
Photo 6 details a 3/4" plywood adapter (with a hole cut to the size of the fan) that separates the heater core from the box. Since the bottom of the box was manufactured with molded-in flanges for strength and rigidity, the adapter joins the box and heater core providing an airtight fit. I opted for the biggest box I could find to allow maximum flexibility. But this forced me to mount the box off-center relative to the core. Photo 7 shows additional 3/4" ply "shims" to support and balance the remainder of the box on the heater core.

Photo 7
The final detail is to ensure adequate air flow through the vent holes. Accomplish this with rubber or wooden spacers attached to the bottom of the core (Photo 3). Find suitable items at Wal-Mart in the hardware section.

Photo 3
With a 100 watt bulb, the box reaches 92 degrees in 15 minutes. Decals are dry and ready for subsequent work in under 20 minutes. Model Master and Pactra enamels are dry in one hour. A Pat Covert eight coat supergloss finish using Testors spray enamels is ready for polishing in 24 hours (a far cry from his recommended 10 days). I have used this dryer for four months and IT WORKS! The box does not overheat or melt. I frequently leave mine on overnight and throughout the next day. Just remember to route the electrical wiring clear of the light bulb (Photo 8).

Photo 8
In addition, before you walk off and leave yours on... test it to see if it performs according to your expectations.

I spent about five hours constructing my dryer. John Noack and I built one for him, too. You might try 1/4" plywood or plexiglass for the heater core if sheet aluminum is unavailable. I would also steer away from the use of a hot plate as a heat source. It may generate too much heat. Good luck!

Materials list

  • 1 polyethylene box sized to suit your requirements
  • 1 comptuer cabinet circulating fan
  • 1 light bulb socket
  • 1 100 watt light bulb
  • 1 socket mounting bracket
  • 1 single pole, single throw switch rated at 115 volts / 15 amps... standard light switch is fine
  • 1 power cord approx. 8-10 feet long
  • 2 pieces of 1/4" masonite or suitable material sized to the dimension of your heater core
  • 4 pieces of 22 gauge aluminum sheet sized to the dimension of the core... plus extra for flanges
  • 20 #8 x 1" sheet metal screws to fasten the masonite tops and bottoms of the heater core
  • 20 1/8" diameter pop-rivets to fasten aluminum... can substitute #8 x 1/2" sheet metal screws
  • 1 piece of air conditioner filter foam approx. 8" x 10"
  • 4 rubber feet/spacers

  • Charles T. Davenport
    IPMS #25544