Re: Seno developer disposal
Hi,
I don't know how to neutralise to pH 8.5 to 9 either, since neutral means pH 7 (I am a science and chemistry teacher...)
Can you check the pH of the solution - can you get pH paper ot tester (beer makers, garden centres and aquarium shops sell them)?
How much chemistry do you know? Here's a brief description, if you don't understand, ask again and I'll give you more details. If you do know, please don't be offended
if I make it too simple...
pH 7 is neutral. Below that is acid, above is alkali. The further away from 7, the stronger the acid or alkali is (0 is most acid, 14 is most alkali)
If a solution is acid, adding enough sodium bicarbonate (baking soda) or chalk will make it neutral (it will fizz, just carbon dioxide). This is a good safe way to neutralise an acid.
If you want to move the pH above 7 you must add an alkali like sodium hydroxide (caustic soda), often sold for cleaning drains, or developing PCB's! Be careful with this, it attacks human flesh *very* nastily, worse than acid. Dissolve a teaspoon of sodium hydroxide in 500ml of water and add slowly, stirring and checking the pH until you reach what you want.
To move the pH down, you need to add acid, such as dilute hydrochloric acid or strong vinegar. Again, add slowly while stirring and checking the pH until you get where you want (probably neutral 7).
OK...
Personally, assuming the pH is above 7 (developer usually is), I would add plenty of white vinegar (it's usually cheaper than hydrochloric acid), then mix with the cheapest casting plaster you can find (don't use cement, it may react) in a strong plastic bag and let it set. Much easier.
Cheers,
FoxyRick.