I cannot remember who gave me these instructions but I found that they worked better than those in A.T.M although I modified them a little as I found some ingredients easier to find than others.
1) Reagents.
Silver nitrate - chlorine free (I made
my own)
potassium hydroxide - pure (I used sodium hydroxide)
ammonia (880)
stannous chloride - technical grade
dextrose (glucose) - pure ( I used a reducing solution as described
in A.T.M book 2 - made from 20fl oz distilled water - 1/8th fl
oz nitric acid - 2 oz sugar - 31/2fl oz iso-propyl-alcohol, all
well matured for 8 month before hand)
Other requirements
whiting
detergent (ordinary washing up liquid)
de-ionised water
tissues or cotton wool
rubber gloves (very important if you dont want to go around
with black hands for the next week!)
stainless steel sink
very clean glassware
2)
Dissolve reagent in 60ml de-ionised water
2oz silver nitrate
2oz potassium hydroxide (I used 1.43g sodium hydroxide)
1g dextrose ( I used 60ml of made up reducing solution)
1g stannous chloride in 1litre tap water.
3) Titration
Using a pipette or dropping funnel add 880 ammonia to the silver nitrate drop by drop - stir well until it clears (mine took about 35 drops to clear from a milky blue to a clear royal blue). Be very careful not to add drops beyond the point where it clears.
Next add to the potassium (sodium) hydroxide, the silver nitrate/ammonia mix. ( dont forget to thoroughly clean every thing after each operation). Now titrate again with 880 ammonia - again do not overshoot end point. It is best to leave solution slightly cloudy. (mine turned nearly blue/black then at about 25 drops turned to clear blue/brown/black?)
Use this solution while it is fresh
4) Cleaning mirror
Carefully wash mirror in waerm water
and detergent to remove dust and major grease marks.
Make up a paste of whiting and 880 ammonia (put on gas mask !!!)
This is best done in the garden as the ammonia fumes will murder
you!! ( I made a huge funnel contraption from thin polyester film
56inches circumference and 46 inches high. This had two holes
for my hands and a slot in the back with a flap on it to get the
mirror in and out. This was all fixed to a glass top table, indoors
with an extractor vent about 7 foot above it - I had no trouble
from fumes).
Scrub the mirror all overusing a swab of tissue dipped in paste.
This must be done very thoroughly, so take plenty of time - 10
minutes minimum.
Wash off with tap water and finally scrub all over again with
a swab of tissue ans stannous chlorine solution - use the whole
1litre (note ; it is best to make up this solution 1 hour before
starting as it is a slow dissolver.
Wash the mirror in tap water and store in a clean bowl filled
with water (the mirror must not be allowed to dry out at any time).
Note; it will help if the water it warm (not hot).
You should have made up previously a
dam from a stiff plastic strip. (I used clear polyester
film). Remove the mirror from the water and place face down on
a formica or glass worktop (to prevent surface of mirror from
drying). Dry sides and back of the mirror. Place dam
around the mirror and tape tightly together with waterproof tape.
Shift the mirror so that the dam is flush with the
back of the mirror. Tape the dam to the back of the mirror to
waterproof it. The mirror will not dry out for several minutes
(Mine did begin to).
This was not at all easy or very good. Sliding the mirror down
was very difficult. The surface began to dry and I got my fingers
on it. Trying to do this without touching the surface or letting
it dry out was near impossible!!
Swill mirror surface with de-ionised
water. Divide the silvering solution in half and dump half of
the dextrose (reducing solution) into one half. Stir quickly and
pour onto mirror surface (goes very dark brown/black). It will
quickly assume a thin silver film. Swill the solution around until
it is evident that deposition has stopped - solution has turned
murky black. Dump the spent solution and give the mirror a quick
swill with de-ionised water. Repeat the process with the other
half of the silvering solution, after adding the dextrose and
stirring as before. Dump the solution and thoroughly wash under
the tap - remove the dam and wash again. Finally swill well with
de-ionised water.
The film will be slightly cloudy but do not
worry about it. (mine was cloudy except where it began to dry
and where my fingers got on it - these areas look well silvered
and not cloudy. Some tiny black fluffy clumps formed
which would not wash off but dried out to a light grey).
Stand the mirror on its edge to drain off, in a dust free
place away from cats, dogs children and any other curious beings!
Do not touch the film. After about a weekyou can try a thoroughly
wahed fingerto try to burnish the film. Do this at the centre
- if the film will stand it, carefully work over the whole surface,
keeping finger clean, dry and frequently washed - if not and the
silver comes off, leave well alone (mine didnt burnish up
very much and even now nearly twenty years later the silvering
has barely changed) Keep the surface covered at all times with
a wad of acrylan.
I found that buying, borrowing, scrounging
or stealing silver nitrate was an impossibility so I decieded
to make my own. Fortunately I got hold of some nitric acid (in
those days all manner of things could be got as health and safety
regulations were almost non existant.
I got an old broken siver pocket watch and used the case. I put
the case in a big glass jar and slowly added the nitric acid (lots
of brown fumes and bubbly blue liquid), I felt like the mad proffessor
(maybe I was/am). I ended up with a quantity of liquid silver
in nitric acid which needed to be reduced to chrystals. I put
a saucepan of water on a small cooker with the solution suspended
over it and over the next few days slowly boiled off the nitric
acid until I was left with about 8 grammes of silver nitrate.
I did this in a large room where I worked Im sure they all
thought I was mad keep running to the cooker and topping it up
with water. Even though I hung a huge funnel, made of sheets of
film over the cooker to take the fumes out through a big extractor
fan, I didnt realise how many fumes got into the room; until
a few weeks later I noticed that that all the ironwork, girders
and even steel rulers had gone rusty (I dont like to think
what it did to my lungs!).