What Is Thermal Mastic?

Thermal Mastic

A smooth, pumpable heat transfer compound or gap filler which is used to promote surface to surface heat transfer between various components or systems. norcold Commonly used in the appliance industry, these compounds can be found in appliances from air conditioners to refrigerators and freezers.

The most effective heat transfer compounds are a mix of three ingredients: the vehicle, the filler and a wetting agent. The vehicle is a low viscosity chlorinated paraffin; the filler is a finely divided inorganic material such as aluminum silicate clay or calcium carbonate; and the wetting agent may be a water soluble oil, such as oleic acid, or a chemically based one.

For the right application, this compound can provide a high temperature resistant joint seal between an evaporator coil and the freezer plate or fins of a cooling unit. In some cases, it can even be used to seal around the evaporator block of an icemaker to prevent air leaks.

In the refrigeration industry, a thick coating of a thermal mastic is applied to evaporator tubing on the cooling compartment and condenser tubing on the outer shell before their placement in freezer cabinets. In the case of a chest freezer, this coating is applied in a continuous head on fashion, resulting in a very large area of thermal contact between the mastic and the refrigeration tubing.

This product is not a miracle worker but it has been shown to be a worthwhile innovation. For example, it is the only one of its kind which provides a significant increase in thermal conductivity between the mastic and the tubing while also retaining the mastic in the insulated cavity of the fridge or freezer.

Using the correct thermal mastic can also make for more efficient operation of your equipment. As well as improving the performance of your ice maker, it will help to avoid defrosting problems on your refrigeration system.

A low cost thermal mastic is compatible with polyurethane foam insulation and can be applied in a wide range of applications where high heat transfer is required. It has a kinematic viscosity of the order of tens of thousand centistokes and is made from the trifecta of a low viscosity chlorinated parafiin vehicle, a finely divided inorganic filler, and a wetting agent.

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