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Sanity Check Please . . . regarding Developer Ratios

John Galt

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I am getting ready to develop some FP4+ shot at box speed with Microdol X. And me, being an engineer started overthinking things again . . . it's a curse :/

I wish to use 1:3 ratio for the Microdol X. My question is this . . . is 1:3 = one part stock solution PLUS 3 parts water, i.e. a 25% solution . . .

. . . OR is it a 33% solution, i.e. 33% stock solution plus 66% water?

Like I said, sanity check please. My inner engineer is steering me toward the latter. One part stock plus two parts water = 1:3
 
This is why some instructions spell this out as 1+3 instead of the usual chemist 1:3
It's definitely not a ratio like 1/3.
 
Thanks Guys . . it was the nomenclature that was stumbling me. 1+3 makes a lot more sense than 1:3. THANKS!!!
 
I guess i never knew what the : meant.
I thought 1:3 was a ratio.?
For every
(1) of ABC
you need
(3) of XYZ
Is that not what 1:3 means.?
 
1:3 is a ratio, but the question becomes "a ratio of what to what"? Is it 1 part of A to 3 parts total (a 33% solution) or 1 part of A to 3 parts of B (a 25% solution); for photographic purposes it is always the latter. 1+3 is a more definitive statement of the ratio.
The ":" means "to".
 
Then let me ask this..... 1:1
How would you guys read read that.?
and so then..... 1:2.....1:3
I have never seen it interpreted the way you guys are saying.
But then i was just blue collar schlub in The Painters Union.
We were often referred to as "less than bright"
 
Most commonly you will encounter the "1:1" nomenclature in Kodak materials.
As indicated above, it is used to indicate the ratio of stock concentrate to diluting water.
I prefer the 1+1 nomenclature, but after decades of using Kodak materials, I don't find it confusing.
What I do find confusing is where is the OP getting current instructions for Microdol-X?
 
CMoore said:
...
I thought 1:3 was a ratio.?
For every
(1) of ABC
you need
(3) of XYZ
Is that not what 1:3 means.?
Click to expand...
Yes, it is a ratio. Yes, that's what it means. There should be no confusion. However, since this is photography, an incessant compulsion to complicate simple things results in continuous overlooking of and perversion of the obvious.

"One part stock to three parts water."​

"One part stock plus three parts water."​

Two unambiguous ways of saying the same thing. Pretty simple.
 
Kodak is not 1 in three it is 1 to three, a proportion not a conventional ratio. Mathematicians have fits with this but chemists are OK with it, so I don't know. This discussion is over 100 years old. Using a proportion rather than a ratio as Kodak intended D-76 1:1 would just be stock D-76 and THAT makes no sense.
 
+1
 
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its funny, it wasn't until i got a usership to APUG in 2003 that i ever heard it was different than 1:1 being 1 part mixed with 1 part or 1 part mixed with 2 parts ( 1:2 ) or 1 part mixed with 3 parts ( 1:3)
no clue why people add the components together .. before "here" ive never saw it with a "+" instead of a : ...

thank you mrs T..
 
Many years ago one manufacturer, I think Johnsons of Hendon, would use both - so say dilutions of a developer were1:10 and 1:15 or 1:20 then for clarity add the 1+9, 1+14. 1+19 in brackets I think in smaller print immediately after.

Ian
 
Ian Grant said:
Many years ago one manufacturer, I think Johnsons of Hendon, would use both - so say dilutions of a developer were1:10 and 1:15 or 1:20 then for clarity add the 1+9, 1+14. 1+19 in brackets I think in smaller print immediately after.
Click to expand...

But just to be clear, 1:10 = 1+10, not 1+9.
 
PhxMedFormatPhotog said:
But just to be clear, 1:10 = 1+10, not 1+9.
Click to expand...

Totally incorrect 1:10 is a ratio and made up by adding 1 part to 9 parts so 1+9, the fact that Eastman Kodak use the wrong term is irrelevant except for their products. Percetol the Ilford equivalent of Microdol-X uses the term 1+3, and Kodak Ltd (UK/Europe) always said 1 part plus 3 parts so 1+3, they never used the ratio.

Ian
 
PhxMedFormatPhotog said:
But just to be clear, 1:10 = 1+10, not 1+9.
Click to expand...


Ian, I believe that you are wrong. It is 1 to 10 as in 1 part to 10 part. What you are talking about is 1:9. Johnsons of Herndon was not following the convention used in chemistry for centuries.
 
.....then what does this mean.?
....1:1
What is your math for this.?

When i mix developer that is 1:9.....I get One Liter of product.
You are saying i should have 900 ml.?
 
Last edited:
1:3 definitely means “1 into 3”, but then again wtf does “one into three” mean?

They should write 1+3.
 
Sirius Glass said:
Ian, I believe that you are wrong. It is 1 to 10 as in 1 part to 10 part. What you are talking about is 1:9. Johnsons of Herndon was not following the convention used in chemistry for centuries.
Click to expand...

Look up what a Ratio means: A 1:10 ratio is a 10% dilution, 1:1000 a 0.1% dilution. 1 to 10 means take one part and water to dilute to 10 that's the ratio, the term "to" doesn't mean plus "+" it means the ratio also denoted as ":".

Kodak Ltd were always very clear, for instance: Take 1 part A, I part B, 1part C, and 7 parts water Kodak D1, that's 1+1+1+7 = 10 parts in total.

CMoore said:
.....then what does this mean.?
....1:1
What is your math for this.?
Click to expand...

The problem is mathematics is plural, so it's maths, there's more than one number

Only Eastman Kodak incorrectly use the term 1:1 others use F.S. for full strength. Kodak incorrectly us the colon : instead of the plus + sign. Their inherent mistake in Chemical instructions wasn't there in their Research papers etc. This is what causes the confusion.

Ian
 

Then we agree!
 
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