At the time of the company’s foundation, the window glass industry was almost exclusively concerned with producing crown glass, which was made by blowing a sphere of molten glass and spinning it out into a circular sheet. This type of manufacture was gradually superseded in the late 1830s and early 1840s with the introduction of cylinder processed sheet glass. With the removal in 1845 of the glass excise duty, the financial advantages enjoyed by crown glass manufacturers disappeared leaving the more modern cylinder process glass makers in a much more favorable position.