Many years ago, the mill acquired an old bolter or flour grader. It had unfortunately seen better days, but now we have almost restored the machine to working order and we anticipate being able to demonstrate it at the May 2026 open day.

The flour that comes from the mill is wholemeal, however, it has been known for many years that if this flour is sieved to remove the bran you are left with a more desirable fine white flour. This could then be used to make white bread. Originally, the sieving was done by hand and was very labour-intensive, so white bread was the preserve of the rich. During the 18th and 19th centuries, the process became mechanised, and by the early 20th century, machines such as ours had become common in mills. Some designs were very sophisticated and incorporated patented improvements that could produce different grades of flour.

In operation, wholemeal flour is fed into one end of a sloping rotating fabric cylinder, which allows the white flour to fall through while the bran continues to the end. Brushes encourage the white flour to pass through the bolting cloth to increase the yield. The white flour falls to the bottom of the machine where an Archimedes screw pushes it to one end where it can be collected. The bran meanwhile falls from the other end, where it too can be collected. Normally, the sides of the bolter would be plain wood, but we have restored ours with
transparent panels so that the workings can be seen.

Although fine white flour is better to cook with, producing it removes much of the goodness that is contained in the germ and the bran. It took a long time for this to be realised, but today white flour has a number of additives to restore some of the lost nutrition. Wholewheat flour, as eaten by the masses, does not of course need them. The flour grader was intended to be used within a mill using the mill power. However, ours will remain as a stand-alone machine using an alternative power source.