Specialised Restoration Services (SRS) considers; the bottleneck in drying is the removal of the bound water within the structure that dictates the duration of the drying process. Studies have shown that you can dehumidify the air in the drying chamber as much as you want but this does little to influence the diffusion rate of the water molecules held within the affected material. Diffusion rates can be influenced by manipulating the temperature of the wet material, making the water molecules within the structure more energetic and increasing the rate at which they move to the surface, where evaporation into the dryer (lower vapour pressure) air occurs.
Water can exist in three different phases; a solid, liquid and a vapour. When water leaves a structure due to evaporation (the phase change from a liquid to a vapour) it takes energy (heat) from the evaporating surface and this is referred to as evaporative cooling. Evaporative cooling is the reason why you can easily spot ‘wet’ areas on a thermal imaging camera; the ‘cold’ spots detected are potentially where water has evaporated from the structure and cooled the material it has left behind.
Example of heat drying systems being used in the restoration industry below: