Many processed materials need to be thermally dried under controlled conditions. Most drying is done in open atmosphere or oxidizing ovens in batch, continuous belt, or tunnel feed styles. However, certain materials require protection from oxygen or other atmospheric contaminants during or after drying. This can be accomplished in a controlled-atmosphere and/or vacuum furnace system.

In addition to the removal of water, water vapor and other impurities being thermally driven off, the temperature could be above the boiling temperature of water (100°C/212°F). Higher temperatures speed the drying process, as long as it does not harm the material being processed. When adding solvents and/or binders, the temperature will need to be adjusted accordingly. The reasoning for the controlled atmosphere is that the material being dried could reabsorb moisture from the atmosphere or be oxidized at elevated temperatures.