Benzotriazole is used as an organic antifoggant and density depressant in developers.

Benzotriazole acts as a restrainer without affecting other properties of the developer. It can also be used as a fog restrainer when processing out dated papers

When blue-black or cold-black image tones are desired with bromide papers, benzotriazole should be used in addition to, or substituted for, potassium bromide

Make a 0.2% solution of benzotriazole (2 grams benzotriazole in water at 125°f/52°c or higher to make 1 liter) then reduce the bromide to 1/10 or 1/6 strength and use just enough Benzotriazole solution to prevent developer stain or fog. A little experimentation may be required.

The same treatment can be applied to chloride and chlorobromide papers to eliminate any greenish black tendencies and/or achieve a blue-black tone.

Related Questions and Answers

Q: 1. What's the particle size?

A: The folks at Photographers' Formulary say, "Our Carbon Black is very, very fine. It might be called an “air float” powder."

Q: 2. Is this a liquid or powder?

A: Powder

Q: 3. Can I use to replicate water drops in fresh/cold bottle drink transpiration?

A: Photographers' Formulary Glycerin (Glycerol) - 100ml can be used create droplets when photographing bottles or drinks.

Q: 4. Can this product be used for Lith developing?

A: Photographers' Formulary Potassium Bromide can be used as an ingredient for lith developer.

Q: 5. What is the expire date of this item?

A: The expiration date is 2017. It does not have a specific one but the manufacture gives it that time frame from when they make it.

Q: 6. Is this harmful to the lungs?

A: Never heard disease because of metol

Q: 7. Is it possible to send it in Canada?

A: The Photographers' Formulary Hydroquinone (100 Grams) is only available for in-store pickup; we can't send it anywhere.

Q: 8. Have these got the wider cap and opening exactly as pictured? I got some of these earlier in the year and the lid and opening were too small to pour chemicals out quickly. I'll upgrade if they've now made them exactly as pictured.

A: The Photographers' Formulary Plastic Bottle (Black, 950mL) does have a wider cap and opening compared to previous versions.

Q: 9. How long is the shelf life once mixed? Is the solution oxygen sensitive?

A: This is from their website:The unused solution keeps indefinitely. After the first use, however, it should not be kept more than two months. Its capacity is about 20 8X10's for paper, 29 rolls of 120film, or 36 exposure 35mm film per liter of working solution.I'm not sure about oxidation, but with at two month shelf life, I don't believe that will be a problem (I am not an expert on this subject).

Q: 10. Can the air be squeezed out to improve shelflife of contents? Is it rigid?

A: The bottle should be mostly full, but it can be squeezed slightly to remove air. It was not designed specifically for this, but I like this bottle better than the collapsible kind because its easier to wash and keep clean between uses.