Good bottling begins with a prior study that enables a correct choice of the type and dimensions of the corks to be used. Choice of Cork »
Storage of the corks
The environmental storage conditions must not cause physicochemical or organoleptic
alterations in the corks.
The humidity of the corks to obtain effective corking is 5% to 8%.
Excessive humidity can cause microbiological changes. On the other hand, corks
that are too dry lose elasticity and therefore their sealing capacity.
Cold makes the cork hard and diminishes its elasticity. Heat softens the cork
which leads to incorrect insertion into the bottle.
Therefore it is indispensable that the storage location is free from odours,
dry and temperate (relative humidity between 50% and 65%, temperature between
15º and 25º C).
The corks must be used within a maximum period of 6 months. Following this
period, the surface treatment applied to the corks can lose some efficacy.
Basic rules for good bottling
.. In the corking phase high pressures inside the bottle should be avoided.
The vacuum bottling system is the most effective method.
. The bottle necks must be absolutely clean and dry in the corking phase,
so as to avoid the formation of a liquid film between the cork and the bottle
which may lead to lateral leaks and/or microbial development.
. The compression of the cork must be slow but its insertion into the bottle should be quick. When compression is too fast creases may form on the surface of the cork. When insertion is too slow the cork begins to recover its diameter before reaching the definitive position, which can lead to deformation of the cork as well as too much pressure inside the bottle.
. Compression undertaken by the jaws must be no more than 30% of the diameter of the cork, so that its diameter is only 1.5 to 2 mm less than the diameter of the bottle neck. Excessive compression can cause deterioration of the cork cells, and consequently harm its elasticity and sealing capacity.
. The empty space between the cork and the wine (head space) must always be over 15 mm, in order to avoid excessively high pressures inside the bottle. The established bottle-filling level must also be complied with.
. Before placing the bottle in lying down position or upside down, a 5-minute period must elapse, to enable the dimensional recovery of the cork against the bottle neck, and thus ensure effective sealing.
. The maintenance, tuning and cleanliness of the corking machine are crucially
important factors to ensure correct and effective bottling. The condition
and adjustment of the jaws must be checked on a regular basis, as well as
the alignment of the corks with the bottles. The maintenance plan recommended
by the manufacturer of the corking machine must be strictly complied with.