Blog and website for William Rubel, author and cook specializing in traditional cuisines

David Jones, at “The Watermill” located in Little Salkheld, just outside of Penrith in Cumbria, England, pointing to the nylon mesh graduated bolting drum at this water powered flour mill.

Historically, and here I am referring to five-hundred years of a written record, flour was sifted through a cloth, called a bolting cloth, to separate the flour from the bran. The oldest way of doing this was to simply put flour in a cloth and shake the flour onto floor where it was then swept up and used. There is nothing inherently unsanitary with this approach — but it was slow. The bolting drum you see in the illustration above permits one to sift flour on a semi-industrial scale. The cloth fitted onto this drum is nylon. A natural fabric, linen, cotton, or silk was obviously used in the pre-modern period. This particular bolter has more than one grade of nylon mesh, so it turns out flour from white to brown — but a brown flour without the coarsest bran and thus whiter than most American whole wheat flours. In the pre-modern period, the baker — including the home baker — might be responsible for bolting the flour used for bread. But whether the baker bolted the flour, or whether the miller bolted the flour, what is important to recognize is that people conceived of flour as a product that ran in fine gradations from the whitest white to the coarsest whole wheat.

In this photograph, the flour sifted out of the bolter at the very top of the photograph, in the upper right, is as white as modern white flour. It is clear from my experiments bolting flour that the one factor that controls flour whiteness is the fineness of the sieve used to sift out the coarse meal. As soon as there was fine cloth it was technically feasible to produce white flour in quantity.

Taking a more subtle approach to bolting flour is a step that American artisinal bakers could take to improve their product. At this time the general approach is to using either white flour or whole wheat flour, with the difference in whole wheat flours being mostly in the fineness of the grind, rather than in the amount of bran left in the meal. Bolting remains a part of English artisinal baking.