Hi, I have a question regarding Tetenal RA4 colour developer and starter solution:- Some months ago (Sept/Oct 2009), I bought a 10L Tetenal RA4 (35degC) kit to use in my Nova Trimate. It came with 80ml starter concentrate. This is added to the fresh colour developer to give it the same characteristics as developer that has been in use for a while. I used about 50ml of the starter to make up my initial batch of just over 2L working strength developer. Just before Christmas, I ran out of paper which temporarily put a halt to my printing session while I wait for a new delivery. Since then, the tank, still full of chemistry, has been sat idle. The colour developer in the tank has darkened considerably (oxidisation). Also the required colour filtration in the enlarger changed considerably towards the end of the session (prints had a considerable yellow/red cast). When my new paper arrives, I am wondering whether to discard the colour developer completely and make up a new batch from the concentrates (I have about half remaining) or to carry on using the old solution. The problem is I have insufficient starter solution left over to make up another 2L working strength developer. Nova sell the Tetenal starter solution separately, but only in 1.5L bottles. Since I am expecting to switch to digital printing for colour work after the current chemistry has been used up, I don't really want to buy a large quantity of starter and throw most of it away. My options seem to be:- 1) Carry on using the old developer and replenish as usual, adjusting the filtration as required. 2) Bite the bullet and buy 1.5L starter, make up fresh developer and throw most of the starter away. 3) Use the remaining 30ml starter to add to an initial 2L of fresh developer and hope that's sufficient. 4) Mix some of the old developer to the fresh batch. The only other option I can think of is to make up my own starter from raw chemicals. The pdf file below suggests it might be a combination of Potassium Bicarbonate and Potassium Chloride. http://www.freestylephoto.biz/pdf/msds/silver/Silver_Pix_RA4_Starter.pdf Any advice :confused: Cheers, Brian.