D-76: full strength or 1:1?

[RalphLambrecht]

e.g. 100ml concentrate + 200ml water?

Tom

Exactly!

 

[Tom Kershaw]

Exactly!

Well at least that is straightforward.

Tom

 

[cmacd123]

I never had a problem with the instructions. Perhaps, just dumb luck on my part.

Yes, I don't know why I never thought of the more complicated ways folks are interpreting this. 1:1 is One of Dose and One of Dat. It is no wonder that writing instructions is a specialized field if there are so many ways of interpreting a simple ratio. No wonder my Grade 13 math teacher (back when we had grade 13) had grey hair.

 

[fotch]

Yes, I don't know why I never thought of the more complicated ways folks are interpreting this. 1:1 is One of Dose and One of Dat. It is no wonder that writing instructions is a specialized field if there are so many ways of interpreting a simple ratio. No wonder my Grade 13 math teacher (back when we had grade 13) had grey hair.

I like Da way u put Dat! Earthy.

 

[RalphLambrecht]

Yes, I don't know why I never thought of the more complicated ways folks are interpreting this. 1:1 is One of Dose and One of Dat. It is no wonder that writing instructions is a specialized field if there are so many ways of interpreting a simple ratio. No wonder my Grade 13 math teacher (back when we had grade 13) had grey hair.

Take two people reading instructions and you get three ways of doing it!

 

[cmacd123]

Because we buy gasoline in liters (or litres) and calculate fuel consumption in miles/gallon?

Depends on where you live. Transport Canada likes to give fuel usage as litres per 100 Km

 

[cmacd123]

BTW, I always get thrown off reading the label on Ilford Rapid Fixer. The label's top gives capacity for 1+4, and if you peel back to read instructions it says 1+3.

I doubled checked that one - and the inside label is for "Ilford Paper Fixer" which I always assumed wias a different product, so I did not compare the instructions.

 

[2F/2F]

Back to the title of this thread. What does 1:1 mean?

I see that some folks write dilutions as 1:1 vs 1+1 for example. I know, people mean the same concentration with both descriptions, but is it?

Let's take another example:

1:3 is what?
1/3 strength or 1 part stock solution + 3 parts water?

When referring to a drawing scale 1:1 means full size. Does it also mean full strength or is it a 50/50 solution, and therefore, 1+1, because that's what we mean when we use it, right?

Confused? Then just look at that:

Kodak uses 1:3, Ilford 1+3 and so does the Film Developing Cookbook and The Massive Development Chart.

Now I'm confused.

What do you think?

Here is what I think, since you asked:

Ratios, expressed with a colon, make perfect sense to me (e.g. 1:1). One part in relation to another part, both of which put into solution together make a volume that is the sum of each of their individual volumes.

So do fractions (e.g. 1/2 stock and 1/2 water). When one sees a ratio such as 1:1, and knows what a ratio states, one automatically sees this as half and half of the whole.

I commonly state formulas both of these ways to other people in person. I use ratios with people who know what I mean, and fractions with people who either don't know or possibly don't know (i.e. students). When writing, I usually use just the ratios.

One can easily relate ratios to fractions. In a ratio, all the numbers on either side of any of the colons, when added together, equal the total number of parts. So, with a 1:3 ratio, you have 1 + 3, and there are four parts. (Which is where the "+" method comes in.) So, when you convert to a fraction, you simply put each number that is separated from another number by a colon over the total number of parts to get what fraction of the total volume each part is.

So, it is all the same junk, IMHO. A ratio is the easiest and most universally academically understood way to state it. Showing the addition of parts that make the total number of parts is just another way of stating it. When it comes to doing the math to figure out how to relate the reduced ratio to the actual solution volume to be mixed, most of us use fractions (and/or percentages) to do the figuring; yet another way to state the same thing.

So, I think 1:1 is the way to most formally state it, 1+1 is a way to state it to help people who may not understand the formal way to figure it out anyhow, and fractions are a way to state it that help people do the actual mathematical operations...but they all properly indicate how to mix ones chemicals.

As for:

I agree, but what would you mix if Kodak is asking for 1:3? I would make it 1/3 stock and the rest water. In other words, 1+2.

A colon used mathematically is not the same thing as a fraction bar. If you read 1:3 as 1/3, you'd have made a mathematical conceptual error. This is why some people choose not to use ratios, and instead use addition signs; to aid in clarity, because some people haven't been informed as to the aforementioned differences...though I am sure you yourself do know the differences, and are just playing Devil's advocate.

 

[RalphLambrecht]

... A colon used mathematically is not the same thing as a fraction bar. If you read 1:3 as 1/3, you'd have made a mathematical conceptual error. This is why some people choose not to use ratios, and instead use addition signs; to aid in clarity, because some people haven't been informed as to the aforementioned differences...though I am sure you yourself do know the differences, and are just playing Devil's advocate.

Yes I was, but it's nice to see that others also think that the addition sign does indeed aid in clarity.

 

[Kirk Keyes]

The confusion comes from a very simple detail that seems to elude most posters -- ratios without stated units are meaningless.

Actually, ratios NEVER need to have stated units. They are a ratio and they are true regardless of the units used for the original material.

 

[djhopscotch]

Actually, ratios NEVER need to have stated units. They are a ratio and they are true regardless of the units used for the original material.

That's only true if both parts of the ratio are using the same unit, then the units with cancel out, otherwise the units of measure are very important.

 

[RalphLambrecht]

That's only true if both parts of the ratio are using the same unit, then the units with cancel out, otherwise the units of measure are very important.

I think you are referring to Kirk's note, not mine.

 

[djhopscotch]

oops, your are correct

 

[DLawson]

Actually, ratios NEVER need to have stated units. They are a ratio and they are true regardless of the units used for the original material.

Perhaps the choice of "units" was poor. They need clearly understood (preferably explicitly stated) defined quantities for the components. If I ask for a screwdriver mixed 1:3, it makes a world of difference if I mean vodka:juice or juice:vodka. Of course, no one cares if the volumes are in fluid ounces, milliliters or gills.

 

[Sully75]

not an expert: but my results have been better since I started running it (and my other chemicals) through a coffee filter. I haven't been able to get 100% of all the solids out of it. Just a thought.

 

[RalphLambrecht]

I agree, my coffee is terrible when I skip the filter!

Just don't know what this has to do with this thread.

 

[Bill Burk]

I dug out an old Kodak Reference Handbook 1954 edition Processing Chemicals and Formulas thinking, if there is ever a place where it will spell it out explicitly, I'd find it there. Well not exactly in a paragraph saying exactly what the 1:1 notation means. But there are several consistent examples where you have both the notation in a grid and a sentence clearly spelled out.
For example Developers, Printing and Enlarging, grid: "Selectol (1:1)" text: "Development Recommendations: Dilute 1 part of stock solution with 1 part of water."

 

[RalphLambrecht]

Thank you Bill for looking this up.

I think there is little doubt that 1:1 is equal to 1+1, and most, if not all, people will see it this way. But, from my workshops and darkroom get-togethers I know that some folks have always been confused with 1:2 and especially 1:3. I confused me at first (40 years ago) too, but it becomes obvious rather quickly.

The point just was: Isn't there less of a chance to misinterpret 1+3 than 1:3?
Many believe so, and except for Kodak, I don't see any manufacturer or publisher of developing charts using the 1:3 notation. Would be nice for all beginners to have a clear standard.

 

[Tony-S]

The confusion comes from a very simple detail that seems to elude most posters -- ratios without stated units are meaningless.

I don't understand this (emp. mine). There are no units in ratios.

Different contexts have different common usage, and within one of those contexts,you are safe. Otherwise, you're just hoping for the best.

This is why the colon should be interpreted as a division sign when expressing the ratios - it makes the math so much easier when calculating volumes.

Kodak's convention is stock:water, some use stock:final_volume, and there are others possible, especially when you get past discussing dilutions.

And Kodak's done a great disservice, IMO.

 

[RalphLambrecht]

Tony

Many see it this way, and I understand why. I think with a little effort it's clear enough, but it certainly could be made more obvious and universally understood.

 

[Ian David]

Wow. I think the one thing that does more to confuse simple folk about this (non-)issue is threads like this.
In the context of mixing consumer photo chemistry, it is obvious that 1:1 and 1+1 mean the same thing, even in Kodak-land. If you have any doubt, look at the front of a packet of Kodak powder. They give different developing times for stock solution and for 1:1, which clearly indicates that 1:1 means 1+1. (And if 1:1 means 1+1, you can safely bet that 1:3 similarly means 1+3).

Ian

 

[Tony-S]

Wow. I think the one thing that does more to confuse simple folk about this (non-)issue is threads like this.

The problem is that 1:1 is the same as undiluted in chemistry parlance. So while it may be confusing to "simple folk", the other way around (saying 1:1 is really 1:2) is confusing to "chemistry folk".

In the context of mixing consumer photo chemistry, it is obvious that 1:1 and 1+1 mean the same thing, even in Kodak-land. If you have any doubt, look at the front of a packet of Kodak powder.

I haven't used Kodak chemistry in decades. "1+1" is obvious to me; "1:1" is also equally obvious - undiluted.

They give different developing times for stock solution and for 1:1, which clearly indicates that 1:1 means 1+1. (And if 1:1 means 1+1, you can safely bet that 1:3 similarly means 1+3).

This is a real problem from Kodak, because no one learns this in chemistry or biology courses. The reason is because it creates extra effort to do simple math. It shouldn't be difficult.

 

[Ian David]

The problem is that 1:1 is the same as undiluted in chemistry parlance. So while it may be confusing to "simple folk", the other way around (saying 1:1 is really 1:2) is confusing to "chemistry folk".

I haven't used Kodak chemistry in decades. "1+1" is obvious to me; "1:1" is also equally obvious - undiluted.

This is a real problem from Kodak, because no one learns this in chemistry or biology courses. The reason is because it creates extra effort to do simple math. It shouldn't be difficult.

I reckon there are a lot more "simple folk" than true "chemistry folk" using photo chemistry, so if a few chemistry folk get confused then it is probably not a huge problem.

The reality is that 1:1 is explicitly distinguished from stock solution in photochemistry parlance.

The maths is not difficult.

Ian

 

[RalphLambrecht]

I reckon there are a lot more "simple folk" than true "chemistry folk" using photo chemistry, so if a few chemistry folk get confused then it is probably not a huge problem. ...

Not a huge problem, but avoidable, 1+1 it is!

 

[2F/2F]

If the goal is to allow mathematically ignorant people to properly mix their photo chemistry, they I think both 1:1 and 1+1 are pretty equally undesirable in the grand scheme of things, compared to simply using fractions, e.g. "1/2 stock, 1/2 water."

1+1 is a little more clear to an ignorant person that is 1:1, simply because there are a lot of uneducated people who don't know what a ratio is.

Then again, if they can't figure out such an incredibly simple thing, should they really get to have us help them out?

I'm sticking with the colon as my way of writing it, and fractions as the way of explaining it in words to students.

The great part of this? Everyone is right...er, correct!