Did you. see
the BBC series “The Great Egg Race” on the 8th of August 1986? The
purpose of that series is to select three teams from various organisations
having electronics and engineering backgrounds to compete together to rnake
workirig devices from bits of wood,
string and rubbish.
In the above
version the teams had to consider that the only water available
was sea-water, but the team must make drinkable water from a home-made
water-still. The sort of equipment that’s available was broken-down
refrigerators and some old camp cooking equipment.
Members of Area
9 will know that I published an article in the Area 9 local newsletter this
year (prior to the “Great Egg Race”) on how to make a simple
water-still. I had in mind to send my article on the water-still to Bill
Reid to put the article into the CR C Newsletter, but since I have had
several pieces of very sound advice on the subject It has made me think that
it is not really worth-while to
make a home-made water-still.
Now the Rev’d
Rona,ld Hatfull, a member of Area 9, is very well qualified in chemistry and
was for many years an analytical chemist and manager of a large laboratory.
Of course at one time, Ronald had distilled water “on tap” for all
photographic purposes, but on leaving the laboratory, that commodity is not
all that easy to obtain. Subsequent experiment showed that with one
exception, the use of distilled water has no advantage over ordinary
tap water.
The exception
was the final wash -when ordinary washing is completed, the film is given a
final soak in distilled water with a few drops of wetting agent, because
hard water at this stage may leave drying marks.
The only
disadvantage with tap-water is
the formation of deposits in alkaline solution such as developers, but
this is easily avoided by the use of Calgon In so far as Ronald is aware,
all commercially prepared developers contain Calgon, or similar There is, of
course, no point in adding Calgon to acid solutions.
Ronald
continued to make other cogent points9 with developers that
contain very sensitive developing agents, it is an advantage to boil
tap-water for a few minutes to expel dissolved oxygen (unwanted oxygen in
developers can alter the pH value and consequently affect the colour
balance) - such boiling will, also, remove part of the hardness. It may be
noted that distilled water that has been stored for any length of time will
also contain dissolved oxygen and should be boiled if such oxygen would be
detrimental.
Members of Area
9 have received a local Newsletter which contained a sketch of a simple
water-still and Ronald pointed out a mistake in the drawing that I made For
those who have got a copy, the upper outlet: for the cooling -water should
be at the highest point -as shown on some of the drawings there would be an
air lock in the upper part of the cooling jacket that will reduce the
efficiency ‘Some drawings went out uncorrected with the outlet not on the
highest point, so if anyone has seen this drawing and is thinking of making
a water-still, remember this point.
Alas, there is
another snag and possibly more serious If one makes a water—still it is
possible you may receive a visit from the local Customs and Excise men! I
(Bob Lewis) have been in touch with that fraternity, and they say you must
notify the fact if you are keeping or using a still, even if you are only making
distilled water.
I sin glad to
say the law was relaxed a little since 1979. You can now apply for
permission to keep a still without an Exice licence under certain
circumstances, such as experimental, analytical or scientific purposes, but
nevertheless you have got to get permission.
As said earlier
in the article, I suggested not to bother all that much with a
water—still, and now I have had further evidence A friend of mine, Brian
Wheatcroft (remember the boffins of Area 5) is another very well qualified
chemist Brian phoned me and pave me similar advice as did Ronald Brian also
said using a kettle element directly in the boiling chamber is not a good
idea. Metal front the element may appear in the distillate, but you might be
able to avoid that snag by obtaining specially coated elements for that
purpose, but they are difficult to obtain.
What about making polypropalene boiling chamber and
let the wave cooker do the boiling. Fit a. plastic steam pipe. from the
boiler and bring it out of the microwave at an angle to prevent radatin
coming into the kitchen, then pass the steam in a Leibig’s condenser. You
can try it, not me, my wife will not allow me to drill holes in her new
Micro!!Since I have now recieved good advice on how
to make-do with a minimum of distilled water, here are my proposals:-
USING
TAP WATER
(1). For the water to make the concentrates and/or the working developers,
boil tap water or a couple of minutes to remove oxygen.
.(2,) Keep the boiled water in a nearly full stopped vessel until you ready
to prepare the developers.
(3) Add Calgon or other similar sequestering
agent in the developers to prevent undesirable deposits from the tap-water
(providing that
the water has not rot already been included in the formula).
(4) And then of
course, keep completed developers in nearly full dark bottles. I say nearly
full because a completely fu1l ’glass bottie could crack if an increase of
temperature happens.
Have
you any proof that your - cause failures from E6 processing ? I have tried
distilled water, de-ionised water, - fridge water. and plain tap water with
equal, results as far as the colour balance is concerned. I may be lucky
with my tap-water supply, although I know the sources vary from. Welsh
Mountain water, .a local reservoir; and from a bore-hol,e, and sometimes a
mixture of all three. All the water seems to be reasonably soft. I never get
furred-up kettles, but sometimes the colour of the water changes when they
have been messing around with the filters or repairing pipes When I have
nearly finished this article I received a letter from Tony Chuter, Area 18.
Tony has been experimenting with various buffer solutions in different
filtered de-ionised, so called ‘distilled’ (Boots Purified), which Tony
is .convinced is de-ionised, even though the manager. swears it is the
“real thing” and tap-water. The interesting thing is that the. pH’ -
even though the water arranged from. 7.9 to 6.0 - originally, the .end
result was partically identical and did. not very more than .2 as a buffer
solution.
The
Final Rinse
Ronald said” earlier that distilled (or de-ionised) water is necessary for
the final wash, and I think he is absolutely right. As an experiment I
collected three sorts of water;’ tap-water; de-ionised water from Halfords
(£1.50 for 5 litres) and finally distilled water from my water-still. I
measured 50m1 of each type into three Pyrex glasses. The three samples were
placed on an electric heater and the water was. boiled away.
The
tap-water left a considerable amount of scale, the water from Halford a left
very, very little scale, and the distilled water from the still left no
scale at all. As a second test I put droplets of each type of water on a
polished plate of optical glass and left the water to dry naturally. 0nly
the’ tap-water’ left a drying mark .I was a little disappointed when I
included wetting agent (Triton X100)”and formaldehyde in the water. Even
with the distilled water there ‘were drying marks on the optical glass.
Of course, I soon
realized that it is bound. to happen when you dry out. dissolved chemicals
so that was no test,. It makes me wonder if there is any point to include
formaldehyde to harden the film;. E6 film is already hardened to deal with
high temperature. Remember those terrible CR50 days when you had to put
Epsom Salts in the water to prevent the emulsion floating away, even at
20deg C.!!
Thus,
with de-ionised water for the final rinse, there should be no drying marks
on the transparencies and by using boiled water for making the developers
there will be another step towards consistent results.