To prepare a canvas, stretch it on a stretcher very well. Then wash it, and it should be very light in color. Next cover the canvas well with a flour gacheta with a little bit of common oil, all applied with a knife. Some make this first layer with flour cooked with retel [sic for retazo?], but this is good only for gilding because for other things it flakes and cracks. When this first preparation has been made, all the loose threads and knots are cut and the canvas is smoothed with pumice stone. After the canvas dries, a putty is made of powdered shells from lakes, mulled very fine on the stone, mixed with linseed oil, and applied with a large knife, as is done usually. The first layer is spread smoothly and worked well, and when it has dried, it is given another layer with more body, and then as many more as needed to cover well. Then it is sanded with the pumice stone and smoothed and scraped with a knife, which should be well sharpened.,If it is washed and stretched again it will remain like this.,