Modern cigarettes produced after the 1950s, although composed mainly of shredded tobacco leaf, use a significant quantity of tobacco processing by-products in the blend. Each cigarette's tobacco blend is made mainly from the leaves of flue-cured brightleaf, burley tobacco, and oriental tobacco. These leaves are selected, processed, and aged prior to blending and filling. The processing of brightleaf and burley tobaccos for tobacco leaf "strips" produces several by-products such as leaf stems, tobacco dust, and tobacco leaf pieces ("small laminate").[9] To improve the economics of producing cigarettes, these by-products are processed separately into forms where they can then be possibly added back into the cigarette blend without an apparent or marked change in the cigarette's quality. The most common tobacco by-products include: