Lovely Vintage Casein or Milk Plastic Beaded Necklace, with thirty-eight off round yellow beads. Each bead measuring 14.85mm.

From the early 1900s until about 1945, casein was commonly used to make many different plastic ornaments, including jewellery, beads, buttons, decorative buckles, fountain pens, knitting needles, the backings for hand-held mirrors, and fancy comb and brush sets. Casein was formed from the combination of milk (a protein) and vinegar (an acid).

Although casein is readily moulded under moderate heat and pressure, it does not produce a stable material for manufacture until it has become hardened by soaking in a 5% solution of formaldehyde in water. After machining, casein can then be polished.

The material readily takes a surface dye, so coloured items can be quickly made from pale coloured stock items. This was especially important for the button trade which was the principal consumer of casein plastics.

Condition: This necklace will need re-threading, the original silk shows some stretching. Lovely colour!

Tip for Identifying Casein: Place it under hot water for a few seconds and it will smell like burnt milk.

Vintage Casein Beaded Necklace