Thin Glass, Colouring on Canvas, and the Smoke of Cities
Blowing flat glass for a picture, a canvas painting recipe with named pigments, and how smoke reads against the sun
Continuing the glass-sealed picture, Leonardo describes blowing glass bubbles between polished bronze or marble plates until they burst into thin, bendable sheets that will not shatter, or drawing out a red-hot plate over a furnace. A recipe 'Way to colour on canvas' then details weak sizing, bristle-brush flesh-tones and sfumato shadow, naming pigments - white lead, lake, giallolino, majolica - and dry retouching with gummed lake and ink for transparent, non-shiny darks. A final note, 'Of the smoke of cities', begins the observation that smoke shows more clearly in the east than the west when the sun stands in the east.
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Blowing thin, bendable glass to seal a painting
Blow glass bubbles between two polished plates of bronze or marble until the breath bursts them, yielding sheets flat and thin enough to bend and stick with varnish to the painting. Being thin, such glass will not break under a blow; a red-hot plate may also be drawn out lengthwise and widthwise over a heated furnace.
Way to colour on canvas, with named pigments
Size the canvas weakly, dry it, draw, and lay flesh-tones with bristle brushes, softening the shadow while fresh. Flesh is white lead, lake and giallolino; shadow is black, majolica and a little lake, or hard chalk; retouch dry with gummed lake, and use gummed lake with ink for transparent darks that shade blue and lake without shining.
Of the smoke of cities, seen against the sun
Smokes are seen better and more distinctly in the eastern parts than the western while the sun stands in the east. The passage opens the discussion continued on the following page.