Volumic Mass – The volumic mass of agglomerated and technical cork stoppers gives indications concerning the consistency of the manufacturing process. Eventually, its compressibility and elasticity may be evaluated by this property.
Humidit y - Cork stopper humidity should be between 5% and 9%.
Surface Treatment – There are two types of products used in the surface treatment: paraffin and silicone. The treatments with paraffin aim at waterproofing as well as improving sealing. The treatments with silicone only aim to lubricate the cork closure, facilitating its insertion during bottling and cork extraction. The type of treatment applied and dosage depend upon the type of wine, the type of bottle, the maturation period and the bottling machine. For the wines that need a maturation period in the bottle (superior to 18 months), a paraffin treatment should be done first followed by a silicone treatment . (texto cortado)
Extraction Force – The extraction force of a cork stopper in a bottle tends to decrease over time. The values advised are between 20 daN and 40 daN (24 hours after bottling).
Visual Standards - The visual classification of cork closures depends on the amount and size of pores (lenticels), bark, belly and cracks found on its surface.
Sampling - Always account for the batch size and follow the accepted standard sample tables, for example the NP 2922 , ISO 2859 or ISO 3951 standard.