Lifespan of Fotospeed LD 20 Lith Developer?
Does anyone know how long Fotospeed LD 20 Lith Developer lasts after being mixed and made into a stock solution?
Also, I mixed a liter of it today and combined it with an older batch I used on January 6th with only one print ran through it. Would mixing it with some old brown affect the lifespan of the developer?
It depends on dilution. I've mixed 20ml A + 20ml B + 1000 ml water, and needed to change / replenish the developer after four 9 1/2 x 12 prints.
Well, I mostly use the default dilution on the package:
15 mL Part A + 15 mL Part B + 970 mL of water.
I'm also asking for the lifespan of the developer while not being used, as I print lith often with a 1 day - 3 days between each printing session.
Justin, the most instructive test I have found to determine the State of the Soup is to simply drop in a test scrap with the lights on. For one, it will tell you if the developer is active. Two, it will show if there is enough semiquinone present (in form of old brown) for infectious development. Three, it will demonstrate need for a restrainer, i.e. KBr or NaCl. (A dash of benzotriazole will also work.)
As I do quite the same as you, printing over the course of a few days, I have found the best way to preserve the activity of the developer is NOT to pour it into a jug for later use. For a small tray, cover it with saran wrap or like plastic wrap, and for large trays a kitchen garbage bag sliced in half will work well.
Press the plastic into contact with solution, and it also seals well along the edges. Work the little bubbles to the sides first.
Oxygen is the enemy. Eliminating surface area eliminates oxygen. Pouring a solution back into a jug (and back into the tray again later) creates turbulence and increases the surface area by untold amounts, albeit for a short time. Perhaps this goes against convention, but when you pour a solution into a jug you have effectively mixed in a giant dose of air; put a cork in it and let it cool, and the O2 has nothing else to do but oxidize your developer. Of course, if you can't leave your tray out, that is a different story.
I don't know the ballpark lifespan, Justin. Throw in a scrap at the start of your print session, and you will have your answer.
I am fairly new with Lith development. But 4 or 5 9.5x12 (24x30 cm) before repenishement is what I have noticed also.
Originally Posted by Tom Kershaw
Last edited by Romary; 01-13-2009 at 03:00 AM. Click to view previous post history.
Reason: ortho + metric sys.
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