


For how long this is gonna continue? I hope this kind of discussion/debates will not make to go back to di...l side, there are enough debates to handle, so i hope film debates will not make me even more regretting to come to this side as well.
Good i started to dilute with '+' notation and not with ':', people here confusing us by debating themselves to each other and we are newbie watching who can win or who is right, each one of you trying to make his statement as a fact or correct, so i am as a new film shooter and English is not language and i am not alchemist or don't know about chemistry, what i should expect to find in this thread?

Originally Posted by TareqPhoto
i am as a new film shooter and English is not language and i am not alchemist or don't know about chemistry, what i should expect to find in this thread?
You're probably better off just ignoring it as most manufacturers use the + notation anyway.
Steve.

Originally Posted by zsas
Matt, that is strange re Ilford fixes, I am seeing it too:
Exhibit 2.2 Rapid Fix, brand new, inside label:
Simon did indicate this is a missprint, Note it says "ILFORD PAPER FIXER" on the inside label. I product that I have never seen offered for sale. I always use 1:4 as it is cheaper and as Simon says seems to work. (200ML concentrate to make a liter of fixer for those that have learned about ratios from other than the Kodak Booklets.)
Charles MacDonald
aa508@ncf.ca
I still live just beyond the fringe in Stittsville

It is common to use 1:3 or 1:4 (1+3 or 1+4) with film and 1:9 (or 1+9) for paper. But, with conflicting instructions it is hard to day. Either 1+3 or 1+4 will work with most all fixers if you adjust fix times to compensate.
PE

Originally Posted by Steve Smith
You're probably better off just ignoring it as most manufacturers use the + notation anyway.
Steve.
Sure, i will use + notation, even if some will use : i will consider it as +.

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Originally Posted by TareqPhoto
Sure, i will use + notation, even if some will use : i will consider it as +.
That's what most of us do.
Steve.

As long as you are consistent in your own practice, you'll be fine.
Develop, stop, fix.... wait.... where's my film?

I have been surprised by the wide variety of methods used in all areas regarding dilution. I think that we must agree to disagree. But,when we post or publish something, we should write or dilution down in clear and unambiguous terms so that everyone else can understand what you have done.
PE

The problem is what we individually think of as clear and unambiguous might not be to someone else.
Before this topic was raised on APUG a few years ago I thought that everyone treated 1:3 the same way as me. i.e. one part to three parts making a total of four and didn't know that anyone thought of it in a different way.
I think we should all use + rather than : As far as I can tell, that is clear and unambiguous.
Steve.

Originally Posted by TonyS
Yuckity yuck.......
It is suprising as you insist on your true. One true.
Sorry, but I regret your students that they don’t teach other ways of the solution preparations, that they won’t meet with other possibilities how to describe a composition of different mixtures (solutions).
Your consideration is based on simple dilution equation:
V(f) × c(f) = V(i) × c(i)
Where V(f) and V(i) are volumes (final and initial) for example in mL and c(f) and c(i) are concentrations (final and initial) for example in mg/L (or mol/L).
From this equation socalled dilution faktor (DF) can be derived.
DF = V(f) / V(i) = c(i) / c(f)
It says how many times the final solution is diluted against the initial solution.
Or, how many times the final solution should be diluted against the initial solution if there is such instructions for preparing the final solution from the initial solution.
DF is greater than 1 and it is expressed by one figure, not by ratio! (Usually)
The reciprocal value can be admited, but I don't like it.
OK, DF (reciprocal value) is your criterion.
But there are more possibilities how to describe composition of mixture.
For example mass fraction, often expressed in percentage, which is fraction of mass of one component to total mass of mixture. Its using is (I hope) very simple. For example water solution of some soluble salt at concentration 20 % (mass fraction = 0,20) means 20 g salt plus 80 g (mL) water.
And now I recommend you to study the following material from IUPAC:
http://pac.iupac.org/publications/pa.../8002x0233.pdf
It si enough to find „mass ratio“.
Do you see that it is possible to describe a composition of mixture by means of such fraction?
This fraction expresses mass of one component to mass of the second component! And the above mentioned example looks 20/80 (=0,25). It is very near to our 1:4. And just such unusual notation gives signal that is 1+4.
And mixing ratio for example 1:0,5 is 1+0,5 etc. (what is your explanation with such recipe?).
And as example I thing was stated earlier. Prepare four components mixture (solids, liquids) in mass ratio 1:0,5:4:20 (where will your explanation be?)
It is no matter if the principle of mass ratio is applied to mixing liquids in volume units.
This mass ratio is known to chemists as relative mass fraction and its application is comfortable in calculations in such technologies as are drying or adsorption. In this case it should be better use for the „normal“ or ordinary mass fraction (related to total mass) name absolute mass fraction, but it is not necessary in ordinary life.
(Two notes to your „serial_dilution“.
1.
The explanation is based on similar dilution equation as is described above:
V(f) × c(f) = V(i) × c(i) + V(s) × c(s)
(s) means solvent and in your case c(s) = 0; V(s) = 9 mL,
But!
This equation is true if V(f) = V(i) + V(s), socalled additivity of volumes is assumed.
Yes, in many many cases of water solutions is true, but this assumption MUST be stressed, especially to students during pedagogical process.
2.
It si important after additon of initial solution to mix final solution before taking a new amount. I am not sure how this mixing is important in bacterial cultivation but I am
fully sure that mixing for preparation the most chemical solutions is very very important.
Both notes (by my opinion) are missing in your serial.)
And in the end some pictures (my serial what means 1:X). It is not necessary to understand in German (even I know very pure German :))
Last edited by H2O; 05262012 at 11:40 AM. Click to view previous post history.

