Stop bath while film processing - is it necessary?

<p>Hi there,<br>

Recently I talk with one of the salesmen in photo shop while I was getting my chemistry. She claimed that using stop bath while film processing in not required.<br>

I usually do this as that was the way I was thought in the college, but that was only evening course so I might missed something.<br>

Thanks for your help.<br>

All the best</p>

<p>Stop Bath will enable your fixer last longer compared to not using it.</p>

<p>I've never used it. As long as your dev times are > 5 mins or so, you can probably get away with just a water bath for 30 seconds or so after the dev step. </p>

<p>Technically, it is not needed, but as Bill said, it helps the fix last longer as it would otherwise use much of its strength to neutralize the developing agents. You can always just buy a jug of white vinegar if you want to save money, I just think that a stop bath is good practice and you should water bath it at least anyway, why not throw in some vinegar in that water!</p>

<p>It is especially not needed if you use a fixer like Photographers' <a href="http://www.photoformulary.com/DesktopModules/StoreProductDetails.aspx?ProductID=137&tabid=9&tabindex=2&LangID=0">TF-4 Formulary Archival Fixer</a> (a print fixer, but works fine on film, but it does not have a hardener).</p>

<p>good advice</p>

<p>I have read that some modern emulsions, possibly Kodak Ilford and the few remailing rolls of Agfa<br>

have a harder emulsion. and can " tolerate" a stop bath<br>

but on the freestyle site where they sell the eastern european films with a more fragile emulsion they<br>

say you SHOULD NOT use a stop bath. these "fragile films" are capable of excellent resuls in terms of contrast and grain and tolaity. but the shock of going from an alkaline developer to an acid fixer can damage them.</p>

<p>I should have typed "from an alkaline developer to an acid stop bath."<br>

stop bath is acetic acid, similar to vivegar. not all fixers are acidic.<br>

but the transition can cause harm without a rinse in water of a SIMILAR temperature to the developer.</p>

<p>Thanks for your great respond,<br>

I think I stay at the stop bath, but I might add some less stoper next time to the water<br>

Best of luck</p>

<p>I use the acid stop bath to stop the developing process as fast as possible... without it, the developing process continues without control. It could be important if you use straigh developers (undiluted) with that shorter developing times (I do). I prefer to use citric acid instead of acetic (a Kodak formula used 15grs per liter)... it is used by the culinary industry, is not harmfull at all, and smells way better. </p>

<p>You probably know, but while citric acid is used by the catering industry (it's what makes lemon juice acidic) so is acetic acid, as it's the majority component of vinegar.</p>

<p>Right. Another interesting acid for stop baths is the boric acid. Also used in the past by the <em>catering</em> industry (thanks Alec) for seafood conservation, it is also not harmful and odorless.<br>

(---Not harmful in reasonable quantities, I mean!---)</p>