Switching to Dry Heat

Curious about dry heat and the new oven systems?  We get a lot of questions about how dry heat works and why we believe ovens are a superior method for preparing thermoplastics. 

What is dry heat?

Dry heat is basically convection heat – a convection oven.  A convection oven uses a fan to circulate warm air throughout the oven to maintain a uniform temperature.  In other words, a convection oven is an oven with a fan inside.

How does dry heat work?

Thermoplastic masks and cushions are heat-activated to become moldable when warmed.  In a water bath, the hot water transfers heat directly to the thermoplastic.  An oven works in the same way.  Convection ovens continuously pull hot air across the thermoplastic, exerting a constant temperature differential that quickly and evenly heats the mask or cushion.

All thermoplastic masks can be prepared in an oven.  The different proprietary methods each thermoplastic manufacturer uses will create small differences in how the thermoplastic reacts to dry heat, just as there are small differences in each type of mask when prepared in water. Any standard thermoplastic device can be prepared in an oven.

Why is dry heat recommended? 

Using dry heat to prepare thermoplastics is beneficial for therapists and patients.  

Therapist Benefits

Ovens warm up quickly – Klarity ovens heat up to working temperatures in six minutes. They can be turned off when not in use, and require very little cleaning.

Masks go straight from the oven to the patient, so there is no need for drying space or damp towels on the counter. Ovens can also be moved easily, on a cart for example, with no worry about water spilling out.

Patient Benefits

A dry thermoplastic mask is more comfortable than a wet slimy mask.  Patients are not getting damp or dripped on.  With water baths, water evaporation accelerates the cooling process, which creates more shrinkage.  Masks prepared in dry heat shrink less and fit better. 

 Less risk of bacterial infection

Ovens are ultimately safer for patients and therapists.  Ovens help reduce the risk of bacterial infection by removing water from the treatment room.

Standing water is nearly always a breeding ground for bacteria unless significant steps are taken to kill the bacteria. At temperatures under 250˚F, bacteria can produce spores that can survive quite extreme conditions for a long period of time. These spores will reproduce and form new colonies when a hospitable environment occurs. Though most mesophilic bacteria and human pathogens will be killed at 165˚F, some mesophiles exhibit increased tolerance to heat when they are exposed to high temperatures for short periods.  Additionally, some heat-tolerant bacteria such as bacillus respond to heat by rapidly forming spores.  The temperature needed to effectively inactivate bacillus spores is well above the range used to heat thermoplastics.  Bacteria can easily take to the air via aerosols, or tiny water droplets if the water is shaken around at all. 

Ovens mitigate the risk of bacterial infection by removing water from the mask making process.  The fans circulating heat throughout the oven create an exceptionally dry atmosphere, so no water, and therefore no waterborne bacteria, is present.


Though switching to dry heat may initially require an adjustment in work flow, once they make the switch, therapists report being much happier overall.  We at Klarity believe that dry heat is a superior method for preparing thermoplastics, and is ultimately safer and better for you and your patients.  We encourage you to check out our new AirFlow Oven, which features a faster heating time and double shelving for heating multiple thermoplastic devices simultaneously.  For more information, please contact us directly.