Well, I've done it now, and I feel a right idiot...
Decided I wanted a warmer tone on some prints, and mixed up a batch of G.262 developer from the instructions in the exellent Darkroom Cookbook.
Exposed my test strip, dropped it in.
Funny, it's developed in 15 seconds! Ah well, I'll give it a full 3 minutes to see what it does...
Nothing more really happened, and the tones were as cold as ever...
Dumped in a lot of water, so the dilution was 1:6. This should give a RED print in 6 minutes or so.
New test: Still 15 seconds, but slightly warmer tones after 6 minutes...
Well, since I had all this developer which didn't give the tones I wanted, I decided to print a batch of postcards. Did that, then left it (the developer, not the batch of postcards!) overnight in the tray.
Next day: Developer is now murky dark brown - try it again for good measure before I throw it out.
Surprise! It still develops nicely in 30 seconds (slowed just a little bit...)!
By now I'm beginning to suspect something's wrong with my chemicals, my water, my mixing, myself, or - finally - the paper.
Digging deep into the box of old stuff in the darkroom (that box has followed me for many years!), I unearth a pack of Ilfobrom. Anyone remember that?
Guess at 2 stops more exposure - just in case the paper's still working. Plonk it in the brown soup.
But then, after five minutes, the print starts developing! And it's brown! Even with bromide cold-tone paper!
Finally I realise that Ilford MG IV RC has incorporated developer in the emulsion. As long as the soup was alkaline enough, the prints would look exactly the same...
I'll have to buy some REAL paper one day.
Are you sure about the paper including developer? The Ilford datasheet seems to imply it doesn't.
That's what I thought too. Another test on Tetenal TT-speed also gave the expected result, then another sheet of MG was done in 30 seconds. At least in MY darkroom, MG IV will be treated as if it has developer in it.
It develops very quickly, but I'm fairly sure they've stopped incorporating developer in the emulsion. An Ilford rep posted something about this on photo.net a while ago, and if I remember correctly, said they removed it for archival reasons, so MG IV RC should be less likely to deteriorate as the earlier RC emulsions did.