Sodium hydroxide is also known as lye, and as a commercial product called Drano (and other registered trademarks) for cleaning out clogged plumbing pipes. These crystals were relatively inexpensive, and were pure enough be used in photographic processing chemistry. But it is difficult to find these products nowadays in the powdered form in the supermarket, as it could be used in the manufacture of crack cocaine or methamphetamine. The typically available drain cleaner in the local supermarket is a concentrated solution of sodium hydroxide, which could give the proer pH for a developer recipe, excet for the fact that the de-clogger also contains sodium hypochlorite, laundry bleach, also good for disoolving organic waste trapped in the pieps, but would remove the gelatin emulsion clean off the glass or film. The crystals can sometimes be found in large farm supply or construction material stores.
Dissolving it in water gives a higher pH than sodium carbonate, and developers that use it, like Holographic Recording Technologies BBAA, Kodak D-8, Photographer's Formulary JD-4, and SM-6 have higher activity than those that are sodium carbonate buffered.
Here is what the Photo-Lab Index from Morgan & Morgan has to say about it: