WEIGHING
& MIXING HINTS & TIPS
A 1% Solution means 1gram
in 100ml of water, or 2grams in 200ml of water, and so
on. Therefore a 0.1% solution would be 0.5gram in 500ml
of water.
As this involves weighing a small quantity and can cause
inaccuracy, it is usual to make a stronger solution...say
1%... and then water
it down. i.e. For 0.1% Pot. Iodide, mix 0.1gram Pot.
Iodide in 100ml of water giving 100mls of 1% solution.
Next take, say, 10mls of the 1% Solution and mix it with
90mls of water, giving 100mls of 0.1% Stock solution. You
would measure from this, the amount required to mix in
the Developer bath. E.G. In First Developer (CRC E6
Formula) mix in 1.2ml for 300ml size, or 2.3ml for 600ml
size.
10%
& 20% Solution.
25 grams dissolved
in 200mls made up to 250mls of water = 10%
solution.
Or 10 grams Dissolved in 75mls made up to 100mls
of water = 10% solution.
10 grams dissolved in 40mls made up to 50mls of
water = 20% solution.
Or 20 grams dissolved 80mls made up to in 100mls
of water = 20% solution.
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W A R N I N G
While 20% solution is about the highest
that is generally used in W&M, You may come across
reference to a 90% Solution of Pot. Hydroxide for use
when correcting pH values. If you try mixing this amount
take extra care as the small volume of water mixed with
Pot. Hydroxide will become extremely hot, and may either
burn your skin, and/or melt the plastic beaker you are
using. ALWAYS POUR ‘POWDER’ INTO WATER, NEVER
‘WATER’ ONTO POWDER.
CONVERTING
FROM 1000ML TO 600, 300, 250mls Etc,
Start with figures for 1000ml (1Litre).
e. g. To find 600ml, 300ml, 500ml & 250ml measures,
divide the 1000ml figure by 100, then multiply the answer
by 60, 30, 50 or 25.
i.e.
First Developer 1000ml. Pot. Carbonate (Hyd) = 12.2gms.
Divide by 100 = 1.122grams, Multiply by 60 = 7.32gms. For
600ml size.
Or Reversal Bath 1000ml. Chelating Agent = 15.0ml. Divide
by 100 = 0.15, Multiply by 30 = 4.5ml. For 300ml size.
Or Colour Developer 1000ml. Pot. Hydroxide = 29.4grams.
Divide by 100 = 0.294, Multiply by 50 = 14.7grams. For
500ml size.
Or Bleach Bath 1000ml. EDTA NAFE = 217.5gms. Divide by
100 = 2.175, Multiply by 25 = 54.375gms. for 250ml size.
MIXING
& STIRRING
Stir water (gently) in beaker before
adding raw chemical into water. Then Stir until powder or
crystals are completely dissolved before adding next
chemical. Stir (briskly) liquid chemicals well, to make
sure they have mixed fully.
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