Hi Kevin,
It might be useful to try to eliminate the cause of your fog, rather than try to get rid of it (prevention rather than cure, if that makes sense.) I don't know the details of your recipe or ingredients so I'll just throw a few out. With simple emulsions, which haven't been chemically sensitized, these can include:
1) non-photographic gelatin
2) light leaks somewhere along the line
3) under-washing, especially if your recipe is made with ammonia (under-washing also show itself as tiny crystals on the dried surface of the emulsion, except on paper coatings.)
4) over-washing without returning a bit of halide to the emulsion
5) over-development, which usually happens when someone thinks that's a good way to get more density.
My standard operating procedure is to wash thoroughly and then return a little KBr (potassium bromide) to the washed noodles before melting them and/or right before coating. Different writers say different things about the 'when' of addition, but honestly, I haven't been able to tell the difference as long as it's added after washing. The rule of thumb seems to be (and it works great for me) to add 1-2 drops of 10% KBr for every gram of silver nitrate in the recipe. Every recipe is different, but so it comes down to a little trial and error. Start with one drop and go up if necessary. At some point, your speed will drop (but that can be hard to detect in slow emulsions). If you still have fog at that point, something else is wrong. If light leaks are eliminated, then the problem is almost certainly in your developer or how you are using it.
Emulsion that is made too diluted (not enough silver halide for a given amount of gelatin and water) is a biggie. The problem can be in the original recipe or (more likely) too much water retained in the washed noodles. Really wring those puppies dry! Having the noodles in a sturdy cloth bag helps. I use a cotton jelly straining bag.
A second way to get thin emulsion is during the coating, even a vigorous emulsion. If it goes on too warm (thin viscosity) or you pour too much off, there won't be enough emulsion on the plate to make a vigorous image.
Over-development can't deliver a good density to a thin emulsion, it will only deliver fog.
Good luck. Looking forward to seeing your tins!
d
