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Photo Forum / Film Photography / Darkroom / December 2005a really stupid question:
thats no lie either. it is, i can admit, very stupid: when mixing formulas does, for instance, 1:4 mean 1 part x to 3 parts y, for a total of 4? or 1 part x to 4 parts y for a total of 5? after years of doing the former im starting to have this creeping uncertainty about it. it just struck me a few days ago that i dont really know for sure, which is really unacceptable, i think. > when mixing formulas does, for instance, 1:4 mean 1 part x to 3 parts > y, for a total of 4? or 1 part x to 4 parts y for a total of 5? after > years of doing the former im starting to have this creeping uncertainty > about it. it just struck me a few days ago that i dont really know for > sure, which is really unacceptable, i think. If you check the Kodak literature, they explicitly state that when they use a term such as 1:4, it refers to the RATIO of stock solution to water. In that case, it would be 1 part stock plus 4 parts water (1+4=5). In different context, when one speaks of a 1 to 5 dilution, it means that 1 volume is diluted to a total volume of 5 volumes. Unfortunately the Kodak ratios are often called dilutions which might lead to confusion. Rather than using 1:4, it would be helpful if the ratio were stated as 1+4. thanks for clarifying this for me. now, if youll excuse me, im going to go re-mix all of my chemicals. or, actually, just increase the dilution accordingly >thats no lie either. it is, i can admit, very stupid: > [quoted text clipped - 3 lines] >about it. it just struck me a few days ago that i dont really know for >sure, which is really unacceptable, i think. 1:4 is a ratio, meaning that for every 1 part of A, you need 4 parts of B. Because people want to interpret this as a fraction (1/4), which is incorrect, it's typically written on photo chemicals as 1+4. So, yes, you've been measuring wrong. Rob "Six parts gin to one part Vermouth" Novak  SignatureStrange, Geometrical Hinges: http://rob.rnovak.net > Rob "Six parts gin to one part Vermouth" Novak The only difference between a Gibson and a Martini is a pearl onion or an olive. And there is an interesting story behind the Gibson. Signature"To announce that there must be no criticism of the President, or that we are to stand by the President, right or wrong, is not only unpatriotic and servile, but is morally treasonable to the American public."--Theodore Roosevelt, May 7, 1918 www.gregblankphoto(dot)com Rob Novak spake thus: > Rob "Six parts gin to one part Vermouth" Novak I take it you don't buy the "bartender glances at the vermouth bottle briefly" school of dry martinis? A friend of mine mixes the greatest martinis in the world (gin or vodka). He never measures anything, and they're always different, and always the greatest. SignatureGod willing, the many crimes of the Bush Administration will eventually be printed in a nice leatherbound, multi-volume edition that will look fantastic on my bookshelf. >I take it you don't buy the "bartender glances at the vermouth bottle >briefly" school of dry martinis? That's not a dry martini. That's not an "ultra-dry," either. That's a glass of cold gin with an olive. If your bartender can't tell the difference, then it's time for a new bartender. If the cigar-boom fratboys want to hold a straight-gin-dick-size-war, more power to 'em. >A friend of mine mixes the greatest martinis in the world (gin or >vodka). He never measures anything, and they're always different, and >always the greatest. I pour by count. I actually buy and use those little pour spouts. Saves having to try to pour into silly jigger measures, and I don't lose the bottle caps once I'm into my fourth cocktail of the night. SignatureStrange, Geometrical Hinges: http://rob.rnovak.net > thats no lie either. it is, i can admit, very stupid: > [quoted text clipped - 3 lines] > about it. it just struck me a few days ago that i dont really know for > sure, which is really unacceptable, i think. As Michael stated I always mix 1+4 to end with 5 and I read 1:4 as 5 total, regardless of notation I make the formula work by adjusting the time to suit my purposes,...a lot less confusing that way. Signature"To announce that there must be no criticism of the President, or that we are to stand by the President, right or wrong, is not only unpatriotic and servile, but is morally treasonable to the American public."--Theodore Roosevelt, May 7, 1918 www.gregblankphoto(dot)com > thats no lie either. it is, i can admit, very stupid: > [quoted text clipped - 3 lines] > about it. it just struck me a few days ago that i dont really know for > sure, which is really unacceptable, i think. It confused me too. If I'm making one liter of a 1:4 formula do I divide 500ml by 4 or 5? I had a brainstorm one day and realized it was 1+4. TADA! No more overdeveloped negs. Now how do they figure out the expansion of the universe? SignatureIt is not our patriotic duty to send children to be butchered & slaughtered & to butcher & slaughter others every time a general or a politician gets a hardon for a war. Rather, it is our patriotic duty to demand the highest burden of proof to justify war. >Now how do they figure out the expansion of the universe? Biggest measuring tape you ever saw. SignatureStrange, Geometrical Hinges: http://rob.rnovak.net if the dilution is 1:4 what i usually do is take 500ml and divide that by 5 that gives me what amount I would use for the concentrate and then top it off with water to the 500ml. easy. duff > thats no lie either. it is, i can admit, very stupid: > [quoted text clipped - 3 lines] > about it. it just struck me a few days ago that i dont really know for > sure, which is really unacceptable, i think. > thats no lie either. it is, i can admit, very stupid: > [quoted text clipped - 7 lines] > really know for > sure, which is really unacceptable, i think. Stating dilutions this way is Kodak practice. 1:4 means 1 part stock to 4 parts water, for a total of 5 parts. Normal chemical practice is to use this notation to mean 1 part of something to 3 parts of something else for a total of 4 parts. No wonder its confusing despite having been used for perhaps a century. Ilford uses a plus sign in its notation, i.e., what Kodak calls 1:4 would be in Ilford notation 1+4, which is a lot more obvious. Over the years most other photo chemical suppliers have followed the Kodak notation or have stated the dilution in words. Signature--- Richard Knoppow Los Angeles, CA, USA dickburk@ix.netcom.com Now I'm happy reading this, Richard!! I thought I was a complete fool thinking 1:4 means: if you have 4 parts in total, 1 part is developer while the other _3_ parts are water so 1:4 = 1 part dev + 3 parts water 1+4 = 1 part dev + 4 parts water. The difference is made by who uses it: a real chemist or Kodak ;-) | > thats no lie either. it is, i can admit, very stupid: | > [quoted text clipped - 20 lines] | followed the Kodak notation or have stated the dilution in | words. > Stating dilutions this way is Kodak practice. 1:4 means 1 >part stock to 4 parts water, for a total of 5 parts. Normal >chemical practice is to use this notation to mean 1 part of >something to 3 parts of something else for a total of 4 >parts. No wonder its confusing despite having been used for >perhaps a century. Er - no. Ratios are ratios, whether we're talking chemicals, people, or widgets. For example, the empirical formula for methane is CH4. The proportional (ratio) notation for methane is C:H=1:4. That's 4 hydrogen atoms to every 1 carbon atom. Five parts. It's the way ratios work. It's not specific to Kodak. 1/4 is "one part out of four". 1:4 is "one part to every four." Always has been. As for citation - the tome I happen to have at hand is "Braille Code of Chemical Notation, 1997 edition" but I'm sure that other texts will concur. SignatureStrange, Geometrical Hinges: http://rob.rnovak.net > > Stating dilutions this way is Kodak practice. 1:4 means 1 > >part stock to 4 parts water, for a total of 5 parts. Normal [quoted text clipped - 15 lines] > way ratios work. It's not specific to Kodak. 1/4 is "one part out of > four". 1:4 is "one part to every four." Always has been. Yes, that's right. In scientific notation 1:4 means four parts. But what Richard was saying is in photo chemistry 1:4 means five parts. >Yes, that's right. In scientific notation 1:4 means four parts. Cite? I'm not being difficult - I'm genuinely curious. Every reference I have at my disposal indicates otherwise. I'd be interested in seeing an example where this is the case. SignatureRob on the Web: http://rob.rnovak.net > >Yes, that's right. In scientific notation 1:4 means four parts. > > Cite? I'm not being difficult - I'm genuinely curious. Every > reference I have at my disposal indicates otherwise. I'd be > interested in seeing an example where this is the case. There's been lengthy discussions on this topic in r.p.d before. A google search will bring some up. Dr. Richard Henry, chemist, MD, author of a textbook on clinical chemistry, many scientific articles, plus the photo reference Controls in Black and White Photgraphy notes on page 88 of his 2nd edition that many photographers "employ 1:2 when they mean 1 part to be diluted/added to 2 parts" for a total of 3 parts. He then says "In most other scientific fields the notation 1:2 has an entirely different meaning, namely, dilute 1 part of the solution to be diluted to a final [total] dilution of 2 parts -- equal parts of each or 1+1." Henry worked mainly as the director of a clinical laboratory of international scope. Richard Knoppow posted the following during a previous discussion on dilution ratio confusion: >...Kodak has been using this form [1:2 = 1+2 for 3 parts total] >for a very long time, Nearly a century, if not longer. It may be >a hold over from old practice or from English practice, which was >often different than US in the past. Keneth Mees and most of his >principle scientists at Kodak Labs were English. |
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