I'm new to lith printing. Matt Blais was over here a couple of days ago to show me the ropes so to speak. We were doing 16 x 20 prints on Ilford MGFB (both glossy and semi matt). I had some lith developer that we used (Rollie). Note that the developer concentrates had been sitting in a half full bottles for a couple of years. We mixed it up at about 1:25 dilution and the first 3 prints or so worked really well. However, after that, we got clumping of the grain as shown in the attached image. We tried some other developer (Moersch) and got one good print, but the second one started doing the same thing. Matt hadn't experienced this before in his work and wasn't sure what was causing it. So - what could be causing this? Is it: - bad developer concentrate that had been sitting in the half full bottles for too long. - bad water - we used tap water to mix the developer. Maybe I should use distilled water. - couldn't have been the paper because we used sheets from 3 different packages. - something else????