Our equipment is supplied untreated as is traditional for wooden bookbinding equipment and as recommended by leading conservation bookbinders. The reason for this being that a finish could when under pressure mark a binding.
However I do have some customers who varnish their equipment and for that we recommend 2 to 3 thin coats of polyurethane varnish (oil based) allowing each coat to dry thoroughly. The first cost should be thinned with 10% white spirit. We do not recommend either oil or wax as this can expand the timber and lock the threads.