 After packaging , the bottles were stored from three to five weeks at 14 – 18 ° C ( 57 – 64 ° F ) in a dark room as the yeast continued to ferment the remaining sugars in the beer . The carbon dioxide that resulted from the fermentation remained trapped in the bottles and dissolved into the liquid , resulting in high levels of carbonation . During this period , an average of four to five percent of the bottles would burst due to carbonation levels exceeding the strength of the bottles . 
