"Mosaic of Quill Cuttings.
For this same work quills of feathers are very nice, cut up very small and stained as I have related.
Mosaic of Paper or Foil.
To lay in these figures as you do on a wall, you must adopt this expedient: take little leaves of gilded or silvered paper, or thick gold or silver foil. Cut it up very small, and lay in with these tweezers, the way you laid in your crushed shells, wherever the ground calls for gold.
Mosaic of Eggshells, Gilded.
Likewise, lay the ground with white shells; wet it with beaten white of egg; wet it with the same as that with which you gild on glass; lay your gold while the ground still draws; let it dry, and burnish with cotton. And this must suffiice for this mosaic or Greek work."
The Craftsman's Handbook (Il Libro dell'Arte) Cennino Cennini (trans. D.Thompson, Jr.)