Safe Disposal of Nitric Acid
Old enamellers generally learnt the hard way what not to do – and often have the scars to remind them. Today, Health and Safety is very properly considered important (even though sometimes one hears grumbles).
In the new Guild DVD on silver, Penny Gildea gives a careful demonstration of how to use nitric acid for etching safely and we are grateful to Zoe Slattery for the following instructions on safe disposal of it.
Neutralising Nitric Acid
Concentrated nitric acid (70% specific gravity) is useful occasionally in enamelling, principally for getting rid of fire stain, or etching. I keep some in the house (in a padlocked cupboard in a locked room – I have a small grand child!) and use it outside, wearing rubber protective clothing. When I have finished with it I then worry about how to dispose of it safely. Chalk is useful for neutralising nitric acid and I am fortunate in having a plentiful supply as I live in an area where we have about a foot of topsoil covering solid chalk. Sodium bicarbonate also works and is readily available. One approach is to add the alkaline material very slowly and carefully to the acid until it stops fizzing, however, working out how much you need is a comparatively simple bit of (GSCE level?) chemistry – here is how to do it for either chalk or sodium bicarbonate.