Hi ! Back at home from an Easter trip to my mother's in law place, I think it is better to start a new thread, than to respond to the old one. I use Xtol since it's introduction, and had only once a failure which was predictable (and did not hurt me...) First : If the A package is cacked, do not mix it. It has got some wet air inside and is probably dead. Ask for a replacement, you may obtain one... Next, boil your tap water and let it settle overnight. This will drive calcium salts into a sludge at the bottom, drive dissolved gasses out, kill all present organical matters, and letting it settle will drive the sludge down. This will ensure a "near perfect" water to mix and keep your product alive. Mixing :I mix the stuff in a 5 liter pail starting with 2,5 or 3 liters water (a rubbermaid one with a transparent window at bottom, which I calibrated to 5liters.) Mix the A part until TOTALLY dissolved, using a big plastic spoon, and crack the small cacked spots in the pail bottom. You may obtain a pale orange liquid, this is normal. (using lukewarm water helps a bit) Mix with B part stir as long as needed (I miss the 1 liter pack which mixed perfectly using my magnetic stirrer...) Try not to put air in the mix, so DO NOT make a vortex by stirring too hard.... (otherwise boilling the water was a waste of electrical power...) Adding part B will clear the orange color if you've got one. Adjust to 5 liters when done. Storage : Use brown 1 liter glass bottles with a tight fitting plastic screwing cap. Check it has a gasket of some sort (mine has a "lip" going inside the collar of the bottle and it is a perfect seal) If possible use bottle used to put medicines. They often are good at keeping oxygen out, and at not leaking.... When you pour one liter on the bottle there is air above the liquid... So add Xtol until the level is at the brim. Close tightly and label properlly, adding the mixing date.... Doing this, you have enough Xtol to complete 4 liters and are left with a partial liter.... Use the remaining to fill small bottles based on the processing tank capacity : My Paterson uses 300 cc for a 135 film. As I use Xtol 1+2, I need 100 CC for one film. So I've bought dark amber bottles of 100 CC with the very same caps as the one liter ones... I preciselly measure 100 CC stock and put it in every 100 Cc bottle. This, as previously, let some air above the liquid. I now top up with water. and close as tightly as I can. Label accordingly. This way, my stock Xtol goes well beyond one year storage ! And it is stored in a room without too much heat in winter and no air cond in summer, just under the roof... Usage : When I need to develop a 135 film, I pour my full Xtol 100 cc bottle in a beaker and add water up to the 300 CC mark. (it is immaterial to check the exact volume I've got in the bottle because I know I have *exactly* 100 cc stock (which was measured out earlier...) ) But you must be carefull when you've topped up, because if some liquid goes above the brim, it's lost, and Murphy's law said that it is stock Xtol going out, not water.... To double check activity, I put the 135 leader in the working strength Xtol during 3 or 4 minutes, during the time it takes to prepare stop bath, fixer, etc... If the leader turns black, Xtol is working. If not, dump it and save your film... When my 100 CC bottles are all empty, I use one 1 Liter bottle to fill them repeating the cycle until all Xtol is used up. I loose a little Xtol this way because I've a little more than one liter to cut into 10 bottle of 100 cc. So you've an option: dump the extra, or use it to top up the 100 CC bottles.....I tend to favor the latter.... It has worked for me since the Xtol introduction, and it gives me one of the finest dev. I know.... I keep all Xtol bottles dedicated to this usage, including the mixing pail and big spoon.... Boilling the water is something I learned when I was a kid in college at my camera club.... So old tricks die hard... Enjoy ! P.S. Claudio Bonavolta ( http://www.bonavolta.ch ) will reach the 3 year storage mark for stock xtol this month using a very similar mixing/storage method.... Maybe he is trying to enter the Guinness book ?