Raising PH of Ilford Rapid Fixer to (near) Neutral for C41/ECN2?

Hello everyone,
I'm in Korea and raw chemistry for DIY, or rather raw chemistry in general, is strictly controlled and my photochemistry importer has run dry of supplies, with no definite date for resupply. I have all my other materials for C41 and ECN2 development, but no fixer. Korea has a available supply of some ammonium thiosulfate Black and White fixers, such as Ilford Rapid Fix, and I was wondering if I could use an alkaline solution to raise the PH of the fixer to the Kodak stated PH of ~6.5.

I am operating under the assumption that an ammonium thiosulfate fixer that is neutral PH and non-hardening would be sufficient as an improvised fixer for C41 and ECN2. If I am mistaken somewhere I would really appreciate some insight, and it would be deeply appreciated.

Thank you so much!

Even an acidic fixer will work OK. If you want to neutralize an acidic fixer, you could use e.g. ammonia and pH test strips to verify the pH. It doesn't have to be very precise.

Welcome to Photrio!

If you can get Ilford Rapid Fix, you should be able to get Fuji Unilec or equivalent C-41 fix.

koraks said:

Even an acidic fixer will work OK. If you want to neutralize an acidic fixer, you could use e.g. ammonia and pH test strips to verify the pH. It doesn't have to be very precise.

Welcome to Photrio!

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Thank you so much. I am just a little worried about the dye stability and integrity, I don't mind jumping through a few hoops for a more assured outcome but the situation is rather quite frustrating. I searched ammonia, and it is also a controlled substance and I don't have the appropriate business license to purchase it, even at 500ML. I suppose there aren't any more easy, but also quality PH buffering solutions available?
My last resort would be to air ship an approved photochemistry from Europe or the US via a courier that handles hazardous materials, the cost of which would be 2-4times the cost of the chemistry itself.

Lachlan Young said:

If you can get Ilford Rapid Fix, you should be able to get Fuji Unilec or equivalent C-41 fix.

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I have searched everywhere and if any conventional alternative were available, I would have bought it. I and many other photographers in Korea have been dealing with the frustrating lack of transparency on why some chemistry (black and white) is allowed and others (C41/EC2/E6) are not. The unofficial consensus seems to be BW is protected under a grandfathered policy about art preservation, but color chemistry appears to be exclusively for labs. I happily support my local lab, but many do not accept push process or cross process orders, even if we offer more payment. Importers for color kits seem to operate under some gray area hence the unpredictable nature of their availability.

perpetualnovice said:

I am just a little worried about the dye stability and integrity

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No need to worry; the dyes are perfectly resistant against an acidic fixer. The 'risk' of an acidic fixer is that the dyes would revert to a colorless state. However, to the extent this happens at all, it's reversible in modern color films and the negatives come out fine if you wash them after fixing, which is something that's supposed to be done anyway.

perpetualnovice said:

I searched ammonia, and it is also a controlled substance

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I suppose that local regulations can vary, but I'm referring to plain old household ammonia in a low concentration as sold around here in supermarkets for cleaning, degreasing etc. If this option is unavailable to you, you could also make or buy a solution of sodium hydroxide or potassium hydroxide (e.g. 10% w/v) and add small amounts of this solution to the acidic fixer until the target pH is reached. If you also cannot obtain potassium or sodium hydroxide (which is likely if you also can't buy ammonia), you might try potassium carbonate or sodium carbonate instead. With the addition of sodium or potassium salts, you will also add sodium resp. potassium ions (obviously), which will slow the fixer and/or reduce its capacity, but this shouldn't be a problem in the amounts you'd add them. However, from a theoretical perspective, ammonia would be preferable.

In the past I have done some tests with commercial rapid fixer and Ammonia solution to bring pH back up to neutral. Of course I could create a neutral fixer this way, but clearing times became noticeably longer than what the original slightly acidic fixer offered.

Therefore I recommend the following: do clip tests with rapid fixer working solution and with the modified one, and extend the recommended fixer times for your C-41 process accordingly. Note, that C-41 materials contain DIR couplers, which release compounds that form very insoluble silver salts. Please use the recommended fixer times from the C-41 data sheets and not just "double clearing time". It's always safe to err on the longer fixer time.

Some time ago, due to circumstances, I found myself without fresh fixer and had to resort to using Ilford rapid fixer as an emergency solution. It is slightly acidic - I raised its pH to around 6 (a quick check with a test strip) by adding baking soda. I used it only once, since I wasn’t sure whether it was sufficiently buffered, and in any case it was an improvised solution. I didn’t notice any visible difference in speed (I fixed in daylight).