Help! I am a photo teacher. It is near the end of the year and we just ran out of Hypo with no budget for buying more. Some black and white projects are still due. Is there a cheap alternative that we can make and use that is SAFE for high school students? How do I make the alternative and what are the guidelines and precautions for using it?
The fix solution you seek is one of the most inexpensive chemicals of the black and white process. You can use most any fixer formulas. In other words, fixer for X-ray, fixer for film and paper. You might buy some from a local camera shop or photo studio. In any event, the stuff is benign. You be at ease, allowing your students to work with it. It has the smell of vinegar because most formulas contain acetic acid (concentrated vinegar). Call or go to your local hospital, they likely will give you a package of X-ray fixer after you plead your case. You can test - swish a snipping of 35mm tongue in paper cup filled with fixer. Do this in the light. You will see the film change from opaque to transparent. Time this reaction. Fix time for film and paper is double the time it takes for the film to clear. If the film does not clear when performing this test, the solution is contaminated of exhausted.
Hospital and dental have mainly phased out chemical based X-ray for digital however, some chemical X-ray is likely in use. Just as likely, the local hospital will have some boxes of fixer in the basement. Make some calls.
Can't say that I've personally tried this one, but my copy of The Darkroom Cookbook reports the following:
- Water at 125F/52C, 2.0 liters
- Sodium thiosulfate, 480.0g
- Sodium bisulfate, 45.0g
Use undiluted. Unlike Plain Hypo this fixer can be saved and reused. It allows easy toning with direct toners, such as selenium.
The plain hypo formula is a bit more simplistic, and I can type if here if you want, but it seems a poor fit for student use because it "has poor keeping qualities." In other words, it's a mix and use, fast, kind of solution.
Here's the CDC guide on Sodium Thiosulfate.
And here's the CDC guide for sodium bisulfate.
As with all chemical mixing processes, it's probably best that you do the mixing, and let your students use the solution with the same cautions they'd normally use with hypo.
Photographer's Formulary has the Bisulfate at 1 lb. for $7.95 (~453g) and the Thiosulfate at $49.95 per 10 lbs. (~4535g).
That would give you ~10 batches of 2 liters each for ~$56 (so, let's say a total volume of 20 liters, or $2.80 / liter)
BH has Ilford's Rapid Fixer at $34.95 / 5 liters and recommends using either a 1+4 or 1+9 dilution. After diluting, the cost per liter is either ~$1.40 (1+4) or ~$0.70 (1+9).
So, making it yourself really only becomes an alternative to buying if you can source the ingredients for significantly cheaper than buying from Photographer's Formulary. Maybe the chemistry department can help you out there?
Plain fixer formula:
750 ml Water
240.0 g Sodium Thiosulfite
1000 ml Water-to-make
Fixing time is around 5 to 10 minutes