Champagne or sparkling wine bottles are much thicker than normal wine bottles to withstand the high carbon dioxide pressure of 3.5 bar and more. In the early days of champagne production in the 18th century, many bottles broke because it was not yet possible to produce an even pressure in a controlled manner. As a rule, champagne bottles are green or dark coloured, in rare cases also white, because of the protection against harmful UV light. The indentation at the bottom of the bottle known as the "Culot de Bouteille" (English: punt) is obligatory. Placomusophilia is the collection of the capsules on the corks. Especially for champagne there are many bottle oversizes; see under bottles. See also under Champagne buckets, Champagne pyramid, Champagne stopper, Sabrieren (champagne heads), sparkling wine and wine enjoyment.