"Demanget-Lapinbleu
"Bain Magique" - Cleaning and Deoxidising concentrate 'HD-13380' "
(it says, on the label....)
Makes a concentrate. Dilute 1+9 with De-ionised or Rain Water before use.
Ammonium Hydroxide solution, s.g. 880g/l
3,700g
Denatured Ethanol (IMS)
1,700g
Soft Soap - as paste
1,200g or as flakes 800g
Distilled / De-ionised Water
1,000g
Oxalic acid, as crystals
480g
We have used this concentrate for many years for the cleaning of clocks, typewriters, adding machines... An horologist friend, more chemist than I, helped work out the proportions. Ammonia solution, used on its own, is alkaline, and eventually eats the metal. The addition of (oxalic) acid produces a bath which is pH neutral (below the surface), and we tested the results by immersing delicate watch-wheels for many weeks, and examining them under the binocular microscope. It eats the oxides, sulphates and such, but not the metal. At all.
Oxalic acid is now a bit expensive, as it is usually only available in 99.99% reagent grade. We used to buy it in bulk from a curious chemical store in Toulon, in a disused arsenal with yard-thick walls and 6" steel doors. It was dirt-cheap, even if we sometimes had to pick out the rat-shit... All the other ingredients are easy to find. We never tried detergents, soap seems to work fine.
Dissolve the Oxalic acid in the water. It will get hot. Heat afterwards to dissolve as much as possible. When cool add the alcohol, soap, and then the ammonia. Use a large enough plastic jerry-can - as you shake to dissolve everything (several times a day, and then before use) ammonia gas is given off. It stinks, you've been warned...
We made a lot of this, and sold it in:
- Litres, for clock makers, antique dealers...
- 125ml, coloured pink, for cleaning jewellery...
- 80ml, coloured blue, for cleaning tubular "Rötring" technical-drawing pens...
All three sizes were the same stuff, and the same price... and, would you know it, the draughtsmen would buy the blue, and the ladies the pink...
Instructions, Caveats
Oxalic acid is a strong organic acid, H2C2O4 , used here because it contains no Sulphur, Chlorine, Nitrogen, etc. It is poisonous. Find out if you're not sure.
- All objects to be cleaned must be completely immersed - the ammonia vapours above the surface are alkaline, and can produce a nasty
"tide-mark".
- Removes paint, given time. We usually kept the used bath for this, in a plastic dustbin with lid.
- Zinc and Cadmium plated objects can be cleaned, but the bath is then sullied and will blacken brass. This effect can be used to "patinate" complicated brass parts, which look crap if they are too clean - but there are other, more controllable, ways.
You can brush the concentrate onto objects which cannot be immersed. The effect is almost instantaneous, but hard to control - rinse immediately.
Pearls, and Opals, might be damaged. Better use toothpaste...
Rinse everything copiously after the bath, with hottest water. High-finish clock parts are sometimes dried in boxwood sawdust, to avoid lime-scale marks if the hard water. A substitute for hard-to-find boxwood is sold by clock-repair suppliers, made from maize. I suspect it is really cous-cous, or polenta, which work just as well... Tricks
of the trade... `(;o)#=
Working with this for many years, I never had a cold. But we had to convince the neighbours that although Ammonia smells like piss, they are not quite the same...