This section is from the book "Cassell's Cyclopaedia Of Mechanics", by Paul N. Hasluck. Also available from Amazon: Cassell's Cyclopaedia Of Mechanics.
Letter cutting on polished granite headstones is executed in the following manner. Set out the letters on tracing-paper (care bein taken that they are evenly spaced) and paste or gum the paper on the stone, keeping the letters in line with a straightedge. When the paste is dry, nick in all the letters with a sharp chisel and remove the paper, if necessary; it is, however, sometimes advantageous to keep the paper on till the work is finished, as the paper saves the surface polish from being scratched. Another way is to cut a slice off a raw potato, make a few cuts on the flat side of the slice, and rub it on the polished surface of the stone; the potato juice dries quickly, furnishes a medium that can be pencilled on, and is easily rubbed off with a piece of damp paper. White of egg, or a very thin smear or coating of size and whiting, can be used for the same purpose. The letters are cut with small cup-headed chisels of various sizes, termed splitters; they are similar to the tools employed for cutting marble, and are used with an iron hammer. The best chisels for this class of work are made from old finely cut gulleting saw files, which are manufactured from the very best steel; these old files may be bought at a very cheap rate per hundredweight, and are easily made up by any toolsmith.
The chisels should be tempered to a dark straw colour, and kept perfectly sharp; a better edge will be preserved if, after every few blows of the hammer, the chisels are dipped into turpentine ; turpentine should also be rubbed on the whetstone. The edge of each letter should be kept perfectly clean and correct in outline, and the internal mitre or depth should form a right angle; the 1 tiers need not be cleaned out or finished at the bottom if they are to be leaded. For the lead or imperishable filling, cut holes in an oblique direction on the sloping side of the letters, one hole at each end and two in the centre of each member (or more, if thought, desirable); use a small drill, and cut the holes sufficiently deep to key in the lead. The lead for filling in should be new sheet, as it is softer than old lead melted up; it should also be a little thicker than the depth of the letter, and should be cut into strips or cut out roughly to the shape of the letter. Lay the lead on the cut letter, and beat in with a boxwood mallet until every portion of the letter is filled and the lead well fastened, then cut off the superfluous lead with a carpenter's chisel until the outline of the letter is found; beat gently home, and bring the letters to an even surface by gritting with pumice-stone, finally finishing off with snake stone (water-of-Ayr) and plenty of water, which gives the letters a dark appearance.
When the surface of the stone is polished, a brass drag with fine teeth is sometimes used to remove the superfluous lead; the drag is traversed backwards and forwards, and avoids all scratching of the polish. For gilding the cut letters, apply a couple of coats of gold size, the first coat mixed with a little yellow ochre to give a body and fill up the pores. When the second coat gets tacky, English gold leaf is applied with a small badger-hair brush and well worked into the mitres, and then cleaned off. The process of gilding, although apparently simple, requires great care and experience.
 
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