confused about dilution

i'm a total beginner at developing black&white; i've only taken one

short course. i bought a jessops econodev and the instructions say

that the dilution for normal speed is 1+12, and for high speed is

1+9. the stopper says 1+10, and the fixer says 1+4/1+9. how much of

each should i mix with, for ex. 1 litre of water? and what do they

mean by capacity: 2.3(normal speed) and 2.9(high speed)? sorry if

the questions seem kind of dull, but i really need help. thx.

for 1+9 (10% final strength) add 100ml of chemical solution to 900ml of water for final volume of 1000ml. I recall that when making "percentage" solutions from dry chemicals you add 100 grams of chemical to a FINAL volume of 100ml water to make a 100% solution of that chemical-- this is because 100 ml of distilled water weighs 100 grams.

Note that you never start with the final volume of water when mixing dry chemicals in water, always a bit less, generally about 10% less than the final volume. NOTE THAT YOU ALSO NEVER NEVER ADD WATER TO YOUR CHEMICAL solutions! Always add the chemical mix to the water so that there are not issues with overheating of the solutions which could cause dangerous splattering of any strong chemicals.

If we assume you are developing a 35mm film in a Paterson tank, normally 300ml of fluid is used. So if your developer requires you to use a dilution of 1:12, then the total sum is 13. Divide the 300 by 13 which gives you 23.07. You therefore need 23.07ml of developer and 276.93 of water. To make it alot easier, create a working solution of 312ml. Then you need 24ml developer and 288ml of water.

Developers at 1:9 = 10; divide 300 by 10 = 30. 30ml of developer and 270ml of water.

The same method is used for the stop and fix.

1:4 = 5. 300/5 = 60. 60ml fix + 240ml water

1:10 = 11; 300/11 = 27.27ml stop + 272.73ml water. For easy calculation use 308ml of working solution, this way you use 28ml stop + 280ml water.

It follows you need an accurate set of measuring cylinders to get the right mix.

If you are developing a 120 medium format film in a Paterson tank then 500ml of solution will be needed. Same method of calculation.

ie 1:9 = 10; 500/10 = 50. 50ml dev + 450ml water and so on.

Then of course, we could go into Rodinal @ 1:25, 1:50 and 1:100.

All good fun. Enjoy yourself.

Be patient, be meticulous, be very clean in working practices and keep notes for future reference.

If all else fails try Ilford FP4+ & Rodinal @ 1:25.

Good luck.

The dilution is measured as a part of a whole. Thus 1+9 or 1:9 means there is one part of the chemical to 9 parts water, or a total of 10 total parts. Divide the total volume of liquid you wish to mix by 10 that will give you the amount of chemical to add per total liquid volume.

I'm not familiar with Jessops chemicals but I would think the higher dilution of developer (1+12) is for the film rated at its nominal ISO and the 1+9 is for a higher rated exposure index. If "stopper" means the stop bath, dilute it 1 part of chemical to 10 parts of water. The fixer dilutions are probably for film and for paper. Film will be the stronger dilution (1+4), paper will be the more diluted (1+9).

Again, I'm not familiar with the chemicals you are using but this is generally the way photo chemicals are mixed.

Maybe some practical hints:

Use different stopper and fix for paper and film.

Mark it like: paper stop 1+10 , paper fix 1+9 and film stop and film fix 1+4.

By the way 1:50 is 1+49 but in these high dilutions this difference in accuracy is neglectible.

If your developing tank has a volume of 500ml and your developer dilution (high speed) is: 1+9 -> 500/(1+9)= 50ml concentrate + (9X50ml)=450ml water. Total volume 500ml. Watch the developing temperature about mostly 20 degrees C +/- 0,5 degrees C.

I wish you a lot of succes.

best regards,

Robert Vonk

www.FotohuisRoVo.nl

Quote: "If we assume you are developing a 35mm film in a Paterson tank, normally 300ml of fluid is used. So if your developer requires you to use a dilution of 1:12, then the total sum is 13. Divide the 300 by 13 which gives you 23.07. You therefore need 23.07ml of developer and 276.93 of water. To make it alot easier, create a working solution of 312ml. Then you need 24ml developer and 288ml of water."

This is incorrect as described, as 1+12 refers to a final volume of 13 units (one PLUS twelve gives thirteen), while 1:12 generally refers to a RATIO of one part per twelve parts total when dealing in volumetric units. A bit confusing but also straight-forward once you think about the additive versus ratio aspects of the formulas. This is particularly important to understand when doing dilutions where those numbers are the same or very close (such as 1+1, 1+2 and 1:2). I suspect this is why most directions on liquid photographic chemical containers give the "+" description rather than ratios.

And as I noted above, percentages for solids dissolved in liquids refer ultimately to the weights (or more accurately the MASSes) of the component parts. Thus 10 GRAMS of NaCL in 100 ml (aka 100 Grams) of water gives the 10% solution expected (which we expect should then weigh 110 grams total). However, I don't actually believe this is the correct result since we generally bring the FINAL volume to 100ml, and in the end there is actually a bit less than a true 100ml (100 grams) of water in the final solution.

A fine distinction that is probably responsible for a lot of confusion in the photographic world, especially with B&W darkroom formulations. And I'm sorry to say I cannot further clarify the issue on percentages, so perhaps a current chemistry major can give a more precise and accurate answer.

Maria, that sounds like Econotol 2 you have there. You should have a helpful leaflet on the side of the bottle. I have a sheet here with the full list of developing times for Econotol 2, so let me know if you want any additional times.

<p> You should dilute the concentrate with water, and I'd suggest sticking with 1+9 for now, if they have given times for your chosen film. The developer should be made up (diluted) immediately before use and is known as a 'one-shot' developer, so should be thrown away after use.</p>

<p>Don't worry about the capacity, that usually refers to the number of films that can be developed with the contents. Fixer can be diluted at different strengths for film or paper. 1+4 is the concentration required for fixing films. Label the Stop and Fixer bottles so you know what is in them next time. Squeeze any excess air from your developer bottle to avoid oxidation, which will ruin it over time.</p>

<p>I have a handy table at <a href="http://www.geocities.com/ruralwales/dilute.html">http://www.geocities.com/ruralwales/dilute.html</a> for a range of dilutions and volumes. A 35mm tank (takes a single roll of film) will usually hold 300ml, the Paterson 2-reel tank 600ml.</p>