The first stage in the process is to cut the slate to the shape required. Thinner pieces – up to 1" thick – we cut ourselves using hacksaws, coping saws or an electric jigsaw. Larger pieces can come ready-shaped from a monumental mason or the quarry where they are cut using a diamond bladed circular saw.
Although we order our slate with a fine finish on the surface it is invariably damaged or scratched. Consequently much time is spent rubbing the surface with increasingly fine emery papers, until the surface is as smooth as silk. A day is often spent on a large aisle slab to achieve the surface we want, or half a day on a small inscriptional tablet. We do not polish stone or slate, but rub it to a fine eggshell finish.
A simple bevel left by the chisel is a good idea because the sharp arris (edge) of slate is very vunerable.
A further embellishment to the edge can be in the form of a rule. In our case it can take the form of a V- cut or a flat rebate. It is wise to scratch the edges of the rule with the corner of a sharp chisel. The V-cut or rebate can then be cut without fear of breaking or chipping beyond the scratch.
We draw the design onto the slate using a white watercolour pencil which has the advantage of being easily removed with a cloth or a damp thumb. First we rule the lines containing the letters: the top-line and baseline. Then we space out the letters fresh and by eye in fine line. Throughout this process we take the greatest care to keep a sharp point to the pencil so that spacing can be accurately judged.
There are rare occasions when it is necessary to work from full scale drawings supplied by the client, for example a trademark or logo. In these instances it is necessary to transfer a design by a process known as pouncing.
The letter-cutter goes into action with a wooden mallet, an iron hammer and one of steel, a dummy of lead and zinc or of aluminium (depending on the size of letters), and a range of tungsten tipped chisels. Where possible the stone is arranged on an easel so that the light falls over the left shoulder, if you are right-handed. To cut, the end of the chisel is hit with a lettercutter's dummy, a round, not flat faced, hammer. The chisel should be held loosely and the actual cut should result almost entirely from the blows of the dummy, not the pressure of the hand.
If too shallow the chisel will slip over the surface, if too steep, it will not travel.
Care must be taken to achieve the correct angle of the chisel: if too shallow the chisel will slip over the surface, if too steep, it will not travel. The sequence of cuts needed to complete a letter is wide ranging, one golden rule is to cut thinner strokes first.
Letters cut in slate lose their fresh cut contrast with the surface of the slate. To combat this letters are often painted or gilded. A letter can be painted by flooding the letter and the area around it with paint – taking care not to leave too much paint in the letter itself. After a couple of coats the surface of the slate is rubbed smooth to remove the surplus paint.
Gilding is an art in itself. To gild V-cut letters loose leaf gold is used over French size mixed with a touch of yellow. Once again the area surrounding a letter is partially sized and gilded, then a week or so after gilding the surface can be rubbed clean of surplus size and gold.
For tablets and pieces which may be handled frequently we advise finishing the slate with a matt wax varnish.
There are various ways of fixing stones permanently; the method chosen is often dictated by the circumstances of the piece and its location.
With smaller tablets and non-permanent pieces we often use keyhole plates fixed to the back the slate. These can then be simply hung over a screw. The development of quick setting resin bonded glues enables us to fix a slate much more quickly.