Hello Roy, welcome to the caffenol club. Yellow-brownish fog when using table salt is a socalled dichroic fog as my dear friend Robpointed out. It can be wiped off while the film is still wet, but that's probably not the best solution.
I made a comparison between salt, iodized salt and pot. bromide and in that order the anti-fog-power increases.
http://caffenol.blogspot.de/2011/07/salt-in-soup.htmlIodized salt in the US has twice as much iodine than the european and is supposed to work better, but the winner is pot. bromide hands down. If you want to use salt, try to use not more than 10 g/l to avoid dichoic fog.
Pot bromide does not decrease neg contrast, it's vice versa, the fog eats contrast. But fog isn't as bad as many may think. If it's not too extreme, you can print or scan through the fog easily. If you have fog-free negs you never know if shadow detail is already diminished. I scanned almost black fogged films with nice results.
In every case you need a restrainer/anti-fog if you get uneven development f.e. with stand development. But 5 - 10 g/l salt can give you not fog-free but even development.
As said before, this all also depends on the film brand, film speed and expiring date. And yes, Tmax400 is a difficult film in caffenol while Tmax100 is great and easy to handle.
Best - Reinhold
