Heated air flows horizontally through the screens. Metering rolls at the bottom of the screens control the rate of rice flow through the dryer. Rice is subject to lower milling yields if it is dried too quickly.
Quality is maintained by drying in several passes through a dryer.
Between passes, rice is stored in temporary holding bins. This is called tempering and allows moisture levels to equalize within kernels. Most tempering is accomplished in about two hours although drying schedules often dictate that the rice be held for about 24 hours between passes. The two step system works only if flat storage has adequate air flow for drying. Late season drying in flat storage may be slow because of low air temperatures.