They are natural cork stoppers, usually of inferior qualities, that are submitted to a process of colmation of the pores with a mixture of quality cork dust and special glue approved by the FDA (food and Drug Administration), to improve the visual aspect and the mechanical characteristics. 
CORSAN produces colmated corks of all the normal sizes, as well as any other sizes at costumer’s request.
The price of the corks is in accordance with it’s visual qualities.
CORSAN has available some standard qualities – GOLD, ALPHA, BETA and GAMMA, being able to make different qualities for diferent prices by costumer’s request.

Technical data sheet