There are various teas which have additives or different processing than "pure" varieties. Tea is able to easily receive any aroma, which may cause problems in processing, transportation or storage of tea, but can be also advantageously used to prepare scented teas. Tea can be flavoured in large blending drums with perfumes, flavourants, or essential oils added. Although blending and scenting teas can add an additional dimension to tea, the process may also sometimes be used to cover and obscure the quality of sub-standard teas.