Can you re-use c41 chemicals from B&W to colour

[oli_sones]

<p>Hi all,<br>

I have a couple of rolls of C41 B&W that need developing and also a few colour rolls. Is it possible to re-use the chemicals from the B&W or best to mix a fresh batch for the colour? <br>

Thanks!</p>

[Alan Marcus]

<p>The chemicals of the C-41 process, once mixed have a finite shelf life. The color developer contains derivatives of benzene also known as coal oil, since it was initially extracted from coal, the type used to fuel steam engines. The color developer has an affinity for oxygen which it naturally extracts from air dissolved in the waters of the developer. This oxidizes the developer and it reverts back to coal tar which is staining. Also, the presence of coal tar means the developing agent is being exhausted. The shelf life is unpredictable based on the type of bottle and how it was capped and the air space above the surface of the liquid. Likely 6 weeks is safe for a used bottled color developer. If discolored, discard and mix fresh. If still clear and looks like tea, then it’s probably OK. However no one will tell you anything but use at your own risk. The other chemicals are probably OK. The bleach/fix loves and needs oxygen work do its task. The bleach/fix removes metallic silver and silver halides from the film. Look at the liquid, it should be translucent and most are blood red (EDTA + iron) this gives the blood red color. <br>

<br>

The stabilizer is a rinse agent plus a biocide, it should be OK. </p>

[john_shriver]

<p>You can use any mix of C-41 films up to the capacity of your developing kit and it's mixed shelf life. There's no "special" burden of the chromogenic B&W films when processed normally in C-41, they just have different dyes than the color films.</p>

[glen_h]

<p>Also, there is a table of how long to increase the developer time depending on how many rolls have been done.</p>

<p>To me, best is to mix a batch, then do the appropriate number of rolls, then discard.</p>

<p>The capacity should be different for different speed film, but I have never seen a table for that. Otherwise, C41 B&W counts the same as C41 color, and mix all you want. If you do it in a commercial lab, they don't keep them separate. </p>