This section is from the "Encyclopedia Of Practical Receipts And Processes" book, by William B. Dick. Also available from Amazon: Dick's encyclopedia of practical receipts and processes.
2017. To Stain Horn in Imitation of Tortoise-shell. Mix an equal quantity of quicklime and red lead with strong soap lees, lay it on the horn with a small brush, in imitation of the mottle of tortoise-shell; when dry, repeat it two or three times.
2018. To Join or Weld Tortoise-shell or Horn. Provide a pair of pincers or tongs, constructed so as to reach 4 inches beyond the rivet; then have the tortoise-shell filed clean to a lap-joint, carefully observing that there is no grease about it; wet the joint with water, apply the pincers hot, following them with water, and the shell will be joined as if it were one piece. The heat must not be so great as to burn the shell, therefore try it first on a piece of white paper.
2019. To Polish Tortoise-Shell or Horn. Having scraped the work perfectly smooth and level, rub it with very fine sandpaper or Dutch rushes; repeat the rubbing with a bit of felt dipped in very finely powdered charcoal with water, and, lastly, with rotten-stone or putty-powder; and finish with a piece of soft wash-leather, damped with a little sweet oil; or, still better, rub it with sub-nitrate of bismuth by the palm of the hand.
2020. Alabaster. Oriental alabaster is a substance of a pure, semi-translucent whiteness, occasionally found variegated with undulating veins of yellow, red and brown. The common alabaster, usually met with in ornaments etc., is made of gypsum (plaster of Paris), and prepared so as to imitate the genuine. The following receipts are for the gypsum imitation, and not the real alabaster. By using any of the hardening processes, beautiful imitations of marble may be produced, but they require great care and skill.
2021. To Engrave or Etch on Imitation Alabaster. Cover every part of the surface, except those portions to be etched, with a solution of 1 part white wax in 4 parts oil of turpentine, thickening with a little finely powdered white lead; immerse the cast in water for from 20 to 50 hours, according to the effect desired. Then wash off the covering solution with oil of turpentine, and brush over carefully the etched parts with powdered gypsum (plaster of Paris). The etching is produced by the solvent action of the water on the gypsum.
2022. To Harden Alabaster. Expose the unpolished articles for from 12 to 24 hours to a heat about equal to that of a baker's oven; withdraw from the heat, and when considerably cooled, immerse them for from 2 to 5 minutes in pure river water. The operation may be repeated a second time, and 3 or 4 days are" allowed to elapse before polishing them. A weak solution of alum in water may be substituted for the river water.