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1. ## Benzotriazole solution?

I used to purchase the 2% benzotriazole solution from Zone VI. Now that this is not available, I have purchased the powdered benzotriazole from photographers formulary. What is the ratio of powder to distilled water to obtain the 2% solution?

2. A 2% solution would have 2g of benzotriazole in 100ml water.

3. Gary the percentage solutions are based on metric measurements and ignore the form of the items being added together..dry versus wet..volume versus weight. If I have 100ml (A ) and I add 10 ml of a secondary solultion (B) then I have a 10% solution of B into A. If I have 100ml of A and I add 10 grams of B This is also considered a 10% solution. In terms of of only volume or of only weight the items may differ substantially from the sated percent..

4. Claire, your answer is a little incorrect. If you take 10 ml or 10 g of a chemical and dilute it UP TO 100 ml with water then it will be 10% but if you use 100 ml of water it will be less than 10%. Even this must be further defined as weight / vol or vol / vol.

If you weigh the total solution and bring it to 100 g then it becomes wt/wt or vol/wt.

For use, measuring out the solutions in which solvent is volumetric or weight based is done differently. This can be critical in some applications due to the density of different solvents or solutions.

Gary, the benzotriazole may need to be dissolved in alcohol. I don't believe that it dissolves well in water, but then I have not tried lately. I keep mine in either iso propyl alcohol or methyl alcohol.

PE

http://home.att.net/~jeffrey.d.mathi...de/percent.htm

6. The maths problems go away if, instead of saying "percent", you get used to refering to it in terms of gram/Litre, and remember that the volume is that of the finished solution, not the amount of water (or other solvent).

So, my potassium bromide stock solution, which you might call "10%" is 100g/L. If I want a small amount, it is clearly 100mg/mL.

Benzotriazole will dissolve better in water with a bit of sodium sulphite which in most cases will not affect the developer since there will usually be much more sodium sulphite present anyway. Try 20g/L or 30g/L of sodium sulphite in your stock solution.

7. I agreethat my posting lacks accuracy.

8. I have some old gently fogged Agfa paper on hand. I have the benzotriazole crystals but haven't a clue of how much I need to try and reduce the fog levels. Just need a normal start point from some one please.

9. About 0.2 grams of Benzotriazole per liter of developer is a good starting point.

10. Originally Posted by Tom Hoskinson
About 0.2 grams of Benzotriazole per liter of developer is a good starting point.
Thanks Tom. Now back to the darkroom

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