Hi there,
When mixing solutions I'm always confused when instructions tell one to mix up to a certain percentage. I have coped so far, but for the sake of being pedantic...
Example problem: The label on a drum of roller wash reads "mix with up to 25% water." Isn't this very ambiguous? Is that 25% of the final mix or 25% of the initial amount of solvent?
If we have 1 litre of wash in a bottle, we could add 330 ml of water so that water constitutes 25% of the volume of the mixed solution or we could add 250 ml of water which is 25% of the volume of solvent.
The same ambiguity seems to exist in the instructions from some fountain solutions: "Addition: 2-3%" or "dose at 2-4%."
What is the convention here?
I find the instruction "Use at 2-3% dilution" much less ambiguous - this seems to indicate that the solute should constitute 3% of the final solution.
Am I being a real dunce or is there a rule-of-thumb I'm missing?
Thanks!
PS Quoting proportions has to be the most clear - 2:1, 4:1, 1:100 - but you never see those!
When mixing solutions I'm always confused when instructions tell one to mix up to a certain percentage. I have coped so far, but for the sake of being pedantic...
Example problem: The label on a drum of roller wash reads "mix with up to 25% water." Isn't this very ambiguous? Is that 25% of the final mix or 25% of the initial amount of solvent?
If we have 1 litre of wash in a bottle, we could add 330 ml of water so that water constitutes 25% of the volume of the mixed solution or we could add 250 ml of water which is 25% of the volume of solvent.
The same ambiguity seems to exist in the instructions from some fountain solutions: "Addition: 2-3%" or "dose at 2-4%."
What is the convention here?
I find the instruction "Use at 2-3% dilution" much less ambiguous - this seems to indicate that the solute should constitute 3% of the final solution.
Am I being a real dunce or is there a rule-of-thumb I'm missing?
Thanks!
PS Quoting proportions has to be the most clear - 2:1, 4:1, 1:100 - but you never see those!
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