A very old recipe I came across did the following:
1) prepare a buffer solution of 200g sodium hydroxide and 150 0.88 Ammonia solution in 1 litre of water.
2) Mix 90 mls 0.88 ammonia and 35 g of silver nitrate with 1 litre of water and add 70 mls of the buffer solution. Dilute this with 1 litre of water. This is the spraying solution for silver;
3)Dissolve 150g of glucose in 1 litre of water and add 140 mls of formaldehyde. This is the reducer and should be diluted to 65ml/litre with water when sprayed.
This is a very good two part silver spray solution that gives a bright shiny deposit. However, many substrates need to be sensitised before the silver will adhere to it, especially if it is a plastic, so the correct activation process is needed.
Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK