Agitation is often treated as a complicated and mysterious function that a photographer can only master after countless hours of trial and error.
Frankly, agitating the SP-8x10 is so simple that it confuses people. Follow these three guidelines and you should get perfect negatives every time:
First, be sure to presoak. This has nothing to do with preparing the emulsion for processing and everything to keeping the film flat.
- "Taco" the film (curl it emulsion side in like a taco) for ten seconds before placing it in the tray. This lets the water get under it faster.
- Once loaded and with the lid on, add 250-500 ml of water.
- Rock the tray gently until you hear the film "clicking" as the tray rocks. This indicates that it has freed itself from the bottom of the tray.
Second, don't use too much chemistry. This is one situation where too much can be worse than too little! That probably sounds counterintuitive, so we'll explain.
Rocking the tray produces a wave on the surface of the liquid. The old rule of thumb: the wave motion extends below the surface approximately twice the wave height. So the more liquid you have, the less actual agitation occurs at the bottom of the tray.
We've found that 250ml to 300 ml is comfortable range. (We know of photographers who have gotten great results with as little as 200 but that seems a bit risky to us.)
You'll have to make sure your dilution is strong enough but most common developers should be fine.
Third, keep it random! There are two basic approaches to agitation with the SP-8x10.
- Raise/drop technique: Some people have had great success leaving the tray on the table and just lifting one edge of the tray up about one centimeter and then lowering it.
- Lift and swirl: You don't want the liquid flow to follow the same path with every agitation cycle. If it does, you can get artifacts on the negative. Mix it up. We like to tilt side-to-side and then to one corner and then front-to-back. Doesn't really matter as long as it's random.
We hope this answers your biggest questions, if not, send us an email.