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Baking is used commercially to accelerate setting, improve bonding, durability and harden coatings. With care and the right equipment, it can be applied to modelling. Heat can be transfered from the source to the coated surface by three means: molecular vibration conduction through a substance, direct or reflected electro-magnetic radiation through a fluid and contact with a heated fluid, circulated by convection. Since metals are excellent conductors, their temperatures may exceed that measured in surrounding air. Objects should be safely insulated from contact. Radiation can be very effective, if intensity and distance are controlled, as exemplified in auto paint shops using large lamps. Also it does not carry dust. More common in ovens, are convection currents which are circulated by the fact that warm air expands to become less dense and rises. Some use fan forced convection, as do blow dryers and heat guns. The reactions of different media to temperature and time vary drastically. Knowledge of the characteristics is essential. Often literature contains information, but experimentation may be necessary on scrap pieces. Again the note book is helpful. Some adhesives may be weakened or disintegrated by excessive heat. Often the radiation from spray booth, illumination lamps is sufficient for slow baking. However it may be great enough to interfere with leveling or cause blistering or damage. By turning exhaust off and affixing a cover across front, convection heating may be added. A small fan will improve circulation. Maximum accumulated temperature should be verified with a thermometer, before use. Small blow dryers are very useful for quick jobs, but distance controlled temperature and air flow must be closely monitored. A too early application may disturb leveling. For higher temperatures , ovens are suitable, if thermostats cover usable ranges. With the approval of the other half, kitchen ovens may be great, but a discarded toaster oven is more convenient, since setting times may be long. Unfortunately insulation is poor or absent and thermostats may not be reliable. A thorough checkout is required over extended periods, with a good visible thermometer. In most, high radiation heating elements, are exposed. Unless you want to toast or broil your model, direct paths to it should be shielded and only convection currents be used. Since metal racks and pans and holders can get very hot, non metal objects should be insulated from them. Often hard wood and some plastics can withstand the heat. Very frequent checks are required to avoid mishaps. Brass coated with Scalecoat is very often baked at 300 ° F for an indeterminate time to form an excellent bond. A coated scrap brass test piece is inserted and scratched periodically to determine completion. BACK TO PAINTING AND COATING BACK TO METHODS INDEX |
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