In the roaster, the copper concentrate is partially oxidised to produce calcine and sulfur dioxide gas.
Sivetz called for the home roaster to focus on the quality of the bean.
In the 1990s, more electric home roasting equipment became available, including drum roasters, and variations on the fluid-bed roaster.
The project is based on the direct trade/relationship coffee model, in which roasters bypass the traditional importing process and source coffee directly from coffee cooperatives and estates.
Green coffee beans can be kept fresh for 13 years, depending upon storage conditions, and more particular home roasters reduce storage time to 8 or even 1.5 months.
In 1960, two large roasters and a second, larger, reverberatory furnace were constructed to expand the copper smelter capacity to 70,000 t of blister copper per year.
There are a large number of roasters, often available via mail order, and some stand-alone coffee shops or small chains roast their own coffee; compare brewpub.
Almost all of the commercial corn roasters come mounted on a trailer.
