The cork goes through a grinding process similar to that of composite agglomerates. The final grain size obtained depends on the use to be made of the granules, 3 to 10 mm for acoustic agglomerate and 5 to 22 mm for thermal agglomerate.
 

Next, the impurities must be removed, namely wood and bark, using densimetric separators and, possibly, pneumatic separators or rotating blankets. The granules are stored and dried until the ideal moisture content is reached.

 

The granules are placed in autoclaves and, through the action of superheated water vapor at a temperature of between 300-370ºC, they expand and exude their own resin (suberin), allowing agglomeration without any foreign additives. The firing time is between 17 and 30 minutes, depending on the initial moisture content.

 

This results in expanded cork blocks which, once stabilized, are ground and cut into slabs of different thicknesses, usually with band saws, followed by the adjustment of dimensions and squareness with a disc saw. The blocks are packed and stored.