Mixing chemicals by weight

[MrDrizz]

Do any of you mix their chemicals by weight? Seem a way more accurate way to do it.

Also am I right in thinking that you times the ml by the gravity to give you the weight in grams?

Ilford DD-X has a SG of 1.070 so 75ml would be 80.25g

Cheers.

 

[john.margetts]

Solids need to be weighed. Liquids should be measured by volume. For accuracy, you can get graduated pipettes fairly cheaply which is likely to be more accurate than weighing with domestically available scales.

 

[dmb]

Do any of you mix their chemicals by weight? Seem a way more accurate way to do it.

Also am I right in thinking that you times the ml by the gravity to give you the weight in grams?

Ilford DD-X has a SG of 1.070 so 75ml would be 80.25g

Cheers.

The specific gravity of 1.070 is for the developer after dilution to 1+4 so that would not be correct calculation. An approximate sp.g. for neat developer would be (5*1.070)-4 = 1.350 (as long as all liquids at 20°C) so you could calculate the weight of a volume of developer. I have used weighing for measuring very small volumes of liquids in syringes in the lab but for anything over 5ml would use graduated syringe or cylinder of suitable size.

 

[Asha]

Just wing it!
There’s too many variables both in the actual exposure of film and it’s processing to turn it into a hi tech lab experiment.
I use hc-110 which is like syrup.
It gets measured using a teaspoon....yes a teaspoon!
Think of temperature control.
I have 3 thermometers, all read slightly different temperatures if placed in the same solution!!
I don’t choose one over the other, I’ll use whichever I place my hand on first.

Away from photography but a similar situation concerning precision measurements:

My mother would make Yorkshire puddings by weighing and measuring the ingredients....the resulting puds were carp.
I followed my fathers slap dash way of “guessing” the amounts and hey presto, like his puds, they came out ace ( when they weren’t stuck to the insides of the oven! [emoji23])