152v - - - - - Repairing things that have been cast
It happens often that what you have cast has metal overflow, through a fault in the mold, the cast, or the metal. Faults in the mold arise from plaster which is not hard and strong and cannot withstand fire, which is corrected by mixing in crocum. If you use too much tin to cast things that are of an average thickness, it will not release well, because tin that is cast thickly, shrinks and bubbles. Similarly, the things you need to mold hollow can be fantastical to cast. If therefore you happen to have a flaw, have at your disposal a small leather pouch full of fine sand, and having placed it on the edge of a goldsmith’s bench, where one files, place upon it your work, and secure it there with a rope which passes underneath your foot. The sand in your pouch will respond to the pressure of your foot, and will immediately be thicker on one side and thinner on the other. Then immediately with a burin, outline and quickly make the subtle parts of your cast which did not come out, or which did not come out distinctly enough, or with a file or a chaple, remove your metal overflow. If there is a flaw in your materials that has left a hole or something too hollow, scrape it with a burin and make notches around that hole, then make an imprint of this with wax. And place this imprint on a fine lead blade, and in this way mark the appropriate size of lead, or of any other alloy which resembles your casting material the most. Then place this piece of work on the notched part and attach it well with some with yellow latten or copper wire — and if you are dealing with tin or lead rub in some rosin around the edge — and apply all around it the replacement piece some little thin pieces of solder or tin, or any other thing. Then with a hot iron, or above the heat source of the forge, solder it together, and then repair all of this with the aforesaid tools and the appropriate chisels.
at left top margin
For gold or a small work, you will need to attach them to a lead ball, which you will then place on the leather pouch and it will help secure the piece with the rope.
Figure at left middle margin
Figure at left bottom margin