A question......stupid or not

[Neal]

Dear Bruce,

In 99% of photo cases, we are picking nits. In this case I believe the total parts would be 102. The ratio would refer to 1 part A to 1 part B to 100 parts water. Of course, if the formula were 1 percent A, 1 percent B and the rest water, then it would be 100 total parts.

In any case, I doubt either of us would follow instructions from the major manufacturers incorrectly. (at least not too often. ;>) )

Neal Wydra

 

[jleeper]

Originally Posted by Neal View Post

How do you deal with a ratio of 1:1?

Neal Wydra

Straight Stock Solution. Not diluted

Can't be. Kodak regularly lists development times for stock XTOL and XTOL 1:1. This is the case that convinced me Kodak meant 1+1 when they print 1:1. As a ratio, you are correct, 1:1 should mean stock, but obviously not what Kodak had in mind for XTOL 1:1.

Jerry Leeper

 

[wfe]

Here's how Sprint does it and I have always followed this with no problems.

http://www.sprintsystems.com/filmdeveloper.htm

1:9 = 100ml developer plus 900ml water for a total of 1000ml.

Cheers,
Bill

 

[John Bond]

I recently purchased some BW- 65 from Photographers Formulary with the following example in the instructions - To make 1000 ml of working solution at 1:1:5, use 143 ml of solution A, 143 solution B and 714 ml of water. This convention uses the : and + equivilently. It makes for a rather awkard calculation to figure the exact amounts to create a specific volume. It is easier just to add the various components and then see how much volume that makes.

 

[Black Dog]

Here's how Sprint does it and I have always followed this with no problems.

http://www.sprintsystems.com/filmdeveloper.htm

1:9 = 100ml developer plus 900ml water for a total of 1000ml.

Cheers,
Bill

That's what I've done for the last 25 years too with no probs

 

[gainer]

The traditional use of : in math is to indicate a ratio. We see it in such relationships as 1:2::4:8 meaning 1 is to 2 as 4 is to 8, also expressed as 1/2=4/8. If we stick with that usage, 1 part A plus 9 parts B is a ratio of 1/9 =A/B. It also could signify that the amount of A in a total volume V of the solution is 10% of V. It's not so good to use it this way because in some such miIxtures, the final volume is not the total of the volumes combined. Methanol and water is an example. In an application where small differences in proportions make large differences in result, we should be more specific. "Add 1 part of A to 9 parts of B" is quite specific. In a case like "Dilute the stock 1:50" it's not likely to make a difference whether we interpret it as 1+50 or 1+49. A difference in timing or temperature or method of agitation can make as much or more difference in results.

I feel the mud getting thicker.

 

[spb854]

What the hell did I start?! LOL

I hated math in school! LOL

I was a chemistry major before I changed to pharmacy. I'm glad we don't have to deal with the Apothecary system with all the drams and grains like I had to learn. Talk about confusing people !!!

Go to Kodak's site and look at the data sheet for HC-110.

There is a section for "preparing working solutions from concentrate" there.

Ex: 300ml of dilution B (1:31)

It states to use 9ml of concentrate with 291ml of water
That gives you a ratio of 1:31 which gives you a TOTAL of 300ml.

I looked at it THIS way:

1/31 concentrate x 300 total volume = 9.6ml concentrate volume

30/31 water x 300 total volume = 290.3ml water volume

THAT is how I figured up how much I needed to use BEFORE I had looked at the data sheet for HC-110. I was VERY close.

I did the same with Rodinal (1+25) and the negatives came out very remarkable!!!

With the HC-110, it looked like I didn't use a long enough development time as the negatives were thin looking to me. I have had the concentrate for 10+ years and had only used it once before. I'm thinking it's now too old, BUT it DID develop the negatives. I only needed to increase the time, which I didn't.

Sorry if I've ruffled some feathers with this discussion. I only expected to see one or two replies.

Lord, I'd be afraid, VERY afraid, to asked a question about birth control !!! LOL

Steve

 

[dancqu]

Doesn't it indicate "parts" in both
instances and not ratios?

Parts? Don't you mean Odds? As in
odds are 1:9. The whole is the sum
of the parts. At least away from the
track. Dan

 

[eddie gunks]

1:9
1 part of "a"
9 parts of "b"

1:1
1 part "a"
1 part "b"

in the end if you do it the same every time it should be fine....atleast fir B&W chemistry....rocket science may be different.

 

[Bruce Osgood]

SNIP
Sorry if I've ruffled some feathers with this discussion. I only expected to see one or two replies.

LOL

Steve

END SNIP

Just goes to show, that ain't no such thing as a dumb question.