Tuesday, September 27, 2011

TCB - Trouble In Paradise

I've been playing with p-aminophenol developers again.  I found that parodinal + ascorbate + borax (RCB) makes for a fine grain full speed developer.  I also found that substituting ascorbate for sulfite in parodinal works too (TCB).  However, doing side-by-side tests as a one-shot developer, I find that I need twice as much ascrobate-parodinal as I do sulfite-parodinal to get the same level of activity.  This bugs me a bit as ascorbate-parodinal is half as efficient as sulfite-parodinal which means I'm wasting a fair amount of  ingredients.

Activity levels aside, the visible difference between the two is the formation of long needle-like crystals in the sulfite version and not in the ascorbate one.  I don't know what the crystals are but if they are p-aminophenol that means that sulfite-parodinal is super-saturated while ascorbate-parodinal is not which would explain the difference in activity levels.  Could it be that the conversion of acetaminophen to p-aminophenol needs sulfite to complete?

I have nothing against sulfite and it's something I stock anyway as I use it in my fix.  I'm just curious about the chemical process here so I can better understand what is going on.  I am not a chemist in any way so I'm hoping to learn from others with more knowledge about this.


No comments:

Post a Comment