Fixer PH

I did a search and really couldn't find the answer I was looking

for, so here goes. Other than dipping litmus paper into it, how does

one know if fixer is alkalaine or not?

I want to try some pyro, and have a large supply of fixer I got from

Freestyle, but have no idea as to its ph. When shopping for fixers

there are lots out there, but other than the stuff from Photographers

Formulary none seem to even mention ph.

One way is to contact the manufacturer or supplier and ask for a copy of the Material Safety Data Sheet (MSDS). They are required to supply these if you ask. The MSDS is usually a couple of pages long and contains details of the hazards associated with a product, giving information on its safe use and handling. pH is one of the items that is required to be listed on the MSDS.

 

Since you mentioned litmus papers, they are not precise enough for what you are wanting to determine here. You should look for some "multistrip" pH determining papers. Follow this link: http://sargentwelch.com/product.asp?pn=WLS65271%5FPK

These have usually 3 or 4 strips of indicating papers attached to the end of a plastic strip. By comparing the colors of each strip of the indiactor papers, you can usually get pH values that are within 1 pH unit, sometimes 1/2 depending on the pH value and your experiance using them.

 

Many rapid fixers such as Ilford Rapid Fix and Hypam have a pH of around 5. The pH will rise a little when used at working strenght. These types of fixers work just fine with pyro. pH 5 to 5.5 is pretty close to neutral. What you don't want to use are fixers that have had acid hardeners added to them. So if you are using a product like Kodak Rapid Fix that has an A and B componant, just don't add in the hardener (the little bottle).

 

Kirk

IS it rapid fixer?

If it is the pH should eb around 5 - 5.5

 

Since I have never bought their stuff, why don;t you give them a call and ask them directly or look at their MSDS, may have them

In fact, pH 7 is neutral. A pH 5 is almost as acidic as acid stop bath (the indicator in Kodak Indicator Stop changes color when pH rises to 5.2, IIRC). That's still too acidic for best results with pyro, according to Anchell and Troop.

 

If it's commercial fixer sold for amateur use, it's easy to tell if it's acidic. If the bottle doesn't say Photographer's Formulary TF-4, it's acidic. The fixers sold for C-41 processing are alkaline, but TF-4 is the only alkaline fixer sold over the counter to plain people in reasonable quantities. TF-4 should have a pH of 8 to 8.5, which is close to that of some developers (some run up to 9).

Bruce,

 

I use C41RA fixer for everything -- Since I moonlight for a lab, I buy it at cost! :)

 

If you can, make a deal for C41 or C41RA fixer with a local minilab to buy it through them.

 

One caution: If it's fixer for C41B or C41RA (as opposed to C41), then it's FAST: 60 seconds is all you need for film!

Donald states: " The fixers sold for C-41 processing are alkaline, but TF-4 is the only alkaline fixer sold over the counter to plain people in reasonable quantities. TF-4 should have a pH of 8 to 8.5, which is close to that of some developers (some run up to 9)."

 

There is one other fixer that could be suitable, which I can buy at my local photo shop. Agfa FX-Universal is made primarily for colour processing but is very good for B&W too. Agfa here (Australia) are now labelling it with B&W dilutions. It can be bought in 1Litre and 5Litre plastic bottles. pH diluted is close to 7. Smells slightly of ammonia, and emits slight SO2 smell in use, but the darkroom is MUCH less smelly compared to using the standard acid fixers.

 

If Agfa turns up its toes in Australia, I will revert to simple hypo plus sodium sulphite with maybe a dash of ammonium chloride to make it a little bit rapid.

There is a very simple, but imprecise test: Smell.

 

Assuming it's a rapid fixer (if it's sold in bottle, it probably is. If sold as dry powder, it probably isn't), it will contain ammonium thiosulfate.

 

All fixers smell. The more acidic the fixer, the more of the typical unplesant sulfuric smell. The more alkaline, the more or the ammonia smell. Many fixers are designed at between pH 6 to 7, where the smell is least. Around 8 the ammonia smell gets (very) noticable, at 5 the sulfuric smell gets unplesant.

"All fixers smell."

 

That's not really true. TF-2 and I guess just plain hypo doesn't. No acid and no amonia. I guess it does have some smell but it's pretty close to zero.

well well, i make an acid rapid fixer with no smell, and everyone can make it also, it´s as easy as to add some borax to the comercial fixer, normally 10 to 15 grams per liter should do, but you can add a bit by bit and check with litmus paper, this will elevate the ph of the fixer, largely reducing or eliminating the sulfur dioxide emissions that makes the acidic smell.

I use acid rapid fixer(ph of about 6-6,5) for prints for 5 minutes

formula contains

sodium thiosulfate 250 gr

Ammonium chloride 50gr

sodium bissulphite 20gr

borax 20 gr

to make 1 liter

 

it´s practically odorless and very cheap

 

for film i use alkaline fixer

formula

sodium thiosulfate 250gr

ammonium chloride 50gr

sodium sulfite 15gr

borax 12gr

 

clears film in less than 30 seconds and has a ph of around 8

i usually fix films for 5 min and t-grain films for 8-10

no problem of overfixing

 

for tanning and staining devs like pmk pirocat-hd and more recentely gainer PQ-TEA i use plain hypo plus ammonium chlodide for 10 minutes, maximum stain i can get.

 

Using ilford rapid fixer or facsimiles add 10 to 15 grams of cheap borax to a liter of diluted fixer and you can get odor free darkroom, if you increase the borax amount you can get a alkaline fixer that washes from film in 5 minutes

It is the acid in fixer that makes it smell of SO2. Fixer does not need to be acidic, unless hardening is required. Modern materials generally do not need hardening.

 

A darkroom that is largely odour-free is much better than one full of SO2 from acid fixer.

Donald Qualls wrote:"In fact, pH 7 is neutral. A pH 5 is almost as acidic as acid stop bath (the indicator in Kodak Indicator Stop changes color when pH rises to 5.2, IIRC). That's still too acidic for best results with pyro, according to Anchell and Troop."

 

and " TF-4 should have a pH of 8 to 8.5, which is close to that of some developers (some run up to 9)."

 

Donald - you are being a little too restrictive in your concepts of pH values the relationship to acidic, basic, and neutral. A fixer with a pH value of 5.5 is only as far from neutral as your pH 8.5 TF-4. For all intents and purposes, pH 5.5 and 8.5 can really be considered neutral.

 

You mention that indicator stop bath changes at pH 5.2 - that is to indicate that the bath has been exhausted. The pH of stop is actually a bit lower than that, somewhere around 3.0 for fresh acetic acid stop. The stop bath has essentially become neutral at pH 5.2 and is no longer effective as a stop.

 

Also, I've tested PMK with acetic acid stop and water rinses, and I find no practical differnce between them. What has your testing found?

 

Kirk

<i>Also, I've tested PMK with acetic acid stop and water rinses, and I find no practical differnce between them. What has your testing found?</i><p>

 

If you reread my previous post, you'll see I was quoting Anchell and Troop concerning acid stops and pyro -- I've never used a pyro developer of any kind.

Just to add more confusion, I went through the MSDS sheets of all the B&W fixers listed at Freestyle. The Kodafix was the most acid, but the rest all were around a ph of 5, give or take a little. So it looks like Photographers formulary stuff may be the only easily available alkaline fixer. I am no chemist for sure, but a ph of 5 does not seem all that acidic to me. I guess I need to read up on pyro more before diving in to see what all the fuss is about.

I prefer the slightly-more-acidic-than-neutral rapid fixers for my pyro negs. I have found that alkaline fixers may reactivate any residual developer in the negative resulting in streaks and spots. I have experienced this only with alkaline fixers and next-to-exhausted dilute rapid fix (i.e. an alkaline environment). The slight acidity of common rapid fixers prevents this. I used TF-4 for a while and have now switched back to Hypam at print strength. No more streaks!

 

Regards

let us not forget that PH number have a factor of ten to each step.

Ph7 is neutral. PH6 is ten time more acidic than 7. PH5 is ten time more acid than 6. ECT.Therefore, PH5 would be 100 time more acidic than PH7.