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# Thread: beginner - 24 exp. vs 36 exp in diluted xtol

1. Originally Posted by Gerald C Koch
To many people 1:3 means 1 part to make a total of 3 parts or 1+2. This why it is better to use the unambiguous notation using the plus sign '+' rather than the colon ':'.
There is no logical reason to take the clear and direct annotation of 1:3 and obfuscating the meaning by using 1+2, unless the goal is to befuddle others out of pure meanness.
1:3 means 1 part to three parts and not 1 part into a total of three parts; "1:3 means 1 part to three parts" is used in chemistry books and cook books.

2. Originally Posted by Sirius Glass
There is no logical reason to take the clear and direct annotation of 1:3 and obfuscating the meaning by using 1+2, unless the goal is to befuddle others out of pure meanness.
1:3 means 1 part to three parts and not 1 part into a total of three parts; "1:3 means 1 part to three parts" is used in chemistry books and cook books.
Most chemists would disagree.

Granted in photography we have long used 1:3 to mean one part concentrate or stock to three parts water. But in chemistry, and thus to some coming to photography from other fields, it's confusing because it means exactly what the post you were responding to said (in fact I had started to point that out myself but every time I do, a weird argument ensues.)

I always prefer the 1+3 nonemnclature because it's clear and unmistakable to BOTH groups - people who only know darkroom work and those coming from other fields that involve mixing solutions.

EDIT: Or, I notice you say it means the same in chemistry. When I took high school chemistry in 1980 and college freshman chemistry a couple of years later 1:3 meant one part in a total of three parts. Maybe that convention has changed since. Never the less, no one mistakes 1+3 while some might mistake the meaning of 1:3.

3. Here we go again...

The ":" can be used to indicate either a ratio or a factor, depending on the commonly-accepted use in the particular field in question. You have dilution ratio (1:3 = 4 parts total) or dilution factor (1:3 = 3 parts total). Basically, only scientists use dilution factor. Pretty much all laymen (and photographers) use it to indicate a ratio; that is what ":" is commonly understood to be in "real world" use. So there should be no confusion in the matter...but if there is, a closer read of the manufacturer's technical data sheets and instructions will clear it up.

4. You're right of course - but why not just write it as "1+3" and be done with it? Since NO ONE will misunderstand that?

5. I am more confused by the plus than by the ratio symbol, since I have never seen it used that way. Numbers separated by ":" clearly indicate that the numbers are meant only to indicate proportions (except in the aforementioned professions). Numbers separated by a "+" indicate that the numbers on either side are the actual amounts to be used in measurement. Anyone who has passed 1st grade math knows that. Using an addition sign to indicate a ratio, against common conventions, is not clear.

And neither of them mean anything without stating what the numbers on each side of the symbols mean. You don't just say "1:3," because it doesn't mean anything by itself. You'd say something along the lines of, "Stock to water 1:3," "One part water to three parts stock," both of which make it abundantly clear. If you say "to" or "ratio," it is immediately clear what is meant.

6. Suit yourself. I've seen 1+3 in photography since at least the 1970s, to indicate one part stock PLUS three parts water. Makes perfect sense to me. We could just write "1 to 3".

Shrug.

7. Older formulas would often say "dilute 1 part of developer with 3 parts of water." A bit wordy but totally unambiguous. The problem is that some mathematically challanged people do not see the ':' as indicating a ratio. People on APUG are fairly frequent in asking dilution problems. Let's make it easy for them. For this I personally prefer the '+' notation.

8. Appreciate getting answers, but can see it would be best if I don't use either the colon or + sigh but spell out exactly what I mean.Amazing how things get sidetracked.

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