This was an article in the January 16th 2026 Newsletter

DRESSING THE STONES.

One of the reasons we need to lift and separate the stones is to allow the grinding faces to be dressed. This means putting the grooves into the face of the stone, because as the stones rotate against themselves a very small amount of stone is worn off and enters your flour. (More about this in the future).

There are a number of different patterns of dressing the stones but the majority these day are done with a basic pattern as shown below.

SECTIONS OF THE MILLSTONES.

The idea is the grains enter at the eye and pass into the grooves which as the runner stone rotates it acts like a pair of scissors and cuts the grain into pieces. As the cut pieces of grain pass towards the edge of the stone due to centrifugal forces, the endosperm and germ (the flour parts) are separated from the bran and ground finer depending on the type of flour being milled. In the case of white flour where the bran has to be sieved off it needs to be left in large pieces, to allow this we use the French Burr Stones.

As the stones slowly wear down their efficiency to grind flour fine decreases. In the case of wholemeal flour this means the stones have to be set closer together or the flow rate of grain entering the stones has to be reduced, slowing the process. In the case of white flour we do have an exact measure of the efficiency of the milling and the stones. To get the white flour we put the meal from the stones through our dresser, and weigh the meal going in and the white flour coming out. We hope for 72% recovery of flour. Occasionally this is lower and we look for a reason, it may be the grain, or sometimes things just haven’t gone as expected. There is no specific setting for the mill it is the millers skill that hopefully ensures that we get the best results.

Eventually all the meals start giving lower than expected recoveries and this is generally due to wear on the stones, as most of the grinding to get fine flour takes place in the outer part of the stones. But eventually we need to dress across all the face of the stone.

In days of old the miller or a travelling millwright would have used a millers bill. A hardened steel chisel that is fastened into a wooden handle. Millstones by their nature tend to be made of hard stones and the bill soon blunts and the dresser would need a good supply. It is a slow process with each part needing a number of hits, so a stone would take the best part of a day to redress.

A MILLERS BILL ON A FRENCH BURR STONE.

However, modern technology speeds this up. We now use an angle grinder with a diamond cutting disc fitted.  Also we can redress the outside of the stone by just lifting the stones and settling them on wooden blocks. We only need to move the runner stone when we need to get to the centre of the stones.

One thing we haven’t done yet is dress the centre of the runner stone. Because we don’t really have space to turn the runner stone completely over, so we are looking at a means of standing it on edge.

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