We’ve come up with a way to easily build a cheap “hot box” to any size you want. Our design will create convection currents and maintains constant temperatures, resulting in even heating of materials which is exactly what you need. The foam board and other materials needed to build the hot box can be found at Home Depot or other DIY stores.
Materials And Tools
2” (5 cm) Foil Insulation Board
1” (2.5 cm) Drywall Screws
Table Saw & Jig Saw
Drill With 1” Hole Saw, Screwdriver Bit, and ¼” Drill Bit
The foil-backed is cut to size carefully on a table saw.
1” (2.5 cm) screws are used to assemble the box.
A jig saw is used to cut a port in the front panel to accommodate the blower end of the heater.
Multiple vent holes are added into the sides of the box. They are sealed with duct tape and can be later opened/closed to vary and control the temperature.
A 1/4” hole is drilled for the thermometer, which is needed to monitor temperature. Thermometers can be purchased through a scientific equipment supply house.
The glass thermometer is inserted in the drilled hole.
The mold is placed in the center of the base board. The base board insulates the mold from the concrete floor. Note: DO NOT place the mold or casting directly on a wood floor, table etc. Only use the hot box on a concrete floor or slab.
The hot box is lowered over the mold and base board, making sure the mold is not too close to the sides and that all sides are flush to the floor.
The heater is fit into the box port. This heater produced an ambient temperature of 203°F (95°C) in 5 min.
Monitor the temperature while heater is operating by viewing the thermometer.
The temperature can be controlled by adding or removing duct tape.
This type of oven can be reconfigured to many sizes. In this example a custom built oven is lowered over a large Mold Max® silicone mold.
This vertical hot box is large enough to accommodate very tall molds for Crystal Clear® castings.
This large hot box is controlled via a digital thermostat. Post curing using heat is crucial in this application, as the pieces will be installed outdoors.