A tea roaster may be a misnomer – it’s more of a hot-air small oven for finishing tea.
Why do you roast tea anyway? Only a small portion of teas, especially oolongs, are finished this way. The “raw” tea used for this purpose is called maocha. It is dried, properly processed and picked clean of twigs and unsuitable leaves, and is thus prepared for the final roasting.
Leaves need to be preserved in some way to stabilize their aroma, flavor and energy, which is why heat has been used for hundreds of years. In the past it came from coal or wood used to heat ovens or kilns, today it is often hot air from electric “modern” roasters.
Tea is usually roasted by individual tea producers, depending on the needs of the merchants or end customers. Or some connoisseurs may roast their own tea in smaller roasters.