# Chemistry: Ratios

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• 11-28-2004, 10:34 AM
photomc
Good explanation Dean..next point is just keep doing what you have been, if you start changing everything - well IT IS Like STARTING OVER.
• 11-28-2004, 10:37 AM
Bruce Osgood
Quote:

Originally Posted by Dean Williams
Look, I just put that last part in there in case Bruce wanted to know how a TRUE ratio was figured.

If we all just replace the colon in a dilution with a plus it will save a lot of head scratching. Remember that first of all.

When Kodak says "D76 1:1" they mean one part D76 and one part water. I don't know why they use the ratio thing here (the colon) instead of a plus sign.

1:0 is a misnomer. You can't have a ratio with only one quantity

1:1 is what we call stock solution. One part developer in a total of one part. That's a 100% solution.

1:2 is half stock and half water.... and so on.

Just remember to replace the colon with a plus sign and all this ratio stuff won't matter.

Now that works for me. Thank you.
1 (Stock) + 1(Water) = a 50% Working Solution.
1 (Stock) + 2(Water) = 33.33% Working Solution.
• 11-28-2004, 12:07 PM
Jorge
I have never heard of true ratios or false for that matter. But the important thing is that it does not matter. As long as you use the notation in the way you understand it consistently you are in good shape. The explanation that 1:10 means one part in a total of ten parts seems unecessarily complicated, If we are going to use scientific notation, we would be talking about solutions with a precise specific gravity, or solutions with molarity, molality etc, etc.

In the end if you make 1 part in 9 or 1 part in 10 the difference is so slight as to have no impact in processing, so people, just do it the way you understand it and do it that way always and you will be fine...
• 11-28-2004, 12:16 PM
TPPhotog
I am so happy that Rodinal states 1+25; 1+50 or 1+100 and my Ilford chemicals 1+4 or 1+9 much much easier to understand. After all as we soup our negs we are cooks not scientists LOL :D

But as already said as long as the dilutions are consistant for your own use, does it really matter. Remember if you always make the same dilution then it becomes a standard for your use and that's all that matters.
• 11-28-2004, 06:04 PM
dancqu
Quote:

Originally Posted by Lee Shively
I used to know how to mix photographic
chemicals. Now I have no idea what I'm doing. Send help. My

I sympathize. I read a thread similar to this a year or two ago
at rec.photo.darkroom. I'd always used the universall convention
of the colon when expressing ratios. I've returned to darkroom work
after many years absence.

I read a number of posts declaring that the unique nature of
photographic chemistry sets it apart from all else when expressing
ratios. So, I adopted the + ; 1+1+8 rather than 1:1:8. The first
reads one part A PLUS one part B PLUS eight parts C while the
second reads one part A TO one part B TO eight parts C.

To make a long story short, I've gone back to the universally
used convention of the colon when expressing ratios. The colon
is just TOO universally used. I think I've been using it for at
least 50 years and not been once out of line in doing so. Dan
• 11-28-2004, 06:50 PM
Lee Shively
I mix D76 1:3. That means I mix 8 ounces of D76 stock solution with 24 ounces of water to make up a total of 32 ounces. When I use it 1:1, I mix 16 ounces of D76 stock solution with 16 ounces of water to make up a total of 32 ounces.

I mix LPD 1:4. That means I mix 10 ounces of LPD stock solution with 40 ounces of water to make up a total of 50 ounces.

I mix Dektol 1:2. That means I mix 16 ounces of Dektol stock solution with 32 ounces of water to make up a total of 48 ounces.

I don't know if it's "+" or ":" that's correct or even if my proportions are correct. I only know it works every time, 100% of the time, to my complete satisfaction.

(I also mix 1.5 ounces of 100% agave tequila with 1 ounce of Cointreau and 2 ounces of fresh squeezed lime juice to make a killer margarita. I have no idea how you write that as a ratio. I just know I need one right now!)
• 11-28-2004, 07:00 PM
TPPhotog
Quote:

Originally Posted by Lee Shively
(I also mix 1.5 ounces of 100% agave tequila with 1 ounce of Cointreau and 2 ounces of fresh squeezed lime juice to make a killer margarita. I have no idea how you write that as a ratio. I just know I need one right now!)

I thought this bit was easy until the question was asked - now I'm as confused as everyone else :confused:

Think I'll join you in your recommended soup here :D
• 11-28-2004, 08:08 PM
jim appleyard
TPPhotog has a great point about consistancy. It's great if YOU know what you mean with whatever sign you use. However, as has been pointed out, the colon is open to interpretation. Maybe I'll be in the minority, but I'm sticking with the "+" sign. With that one there's no doubt. It will always mean x+y=z. But then I've always said "passenger side " or "driver's side". The left or right front of the car isn't accurate enough and depends where you are standing.
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