I'm sorry I was unclear about the sulfuric acid. Kirk is right of course. The reason I have a gallon of 37% Sulfuric Acid is that for a molar equivalent of 1 L of 50% NaOH, you will need about 1 L of 37% Sulfuric Acid, which is the strongest that can be bought on the open market here. You do not dump the acid onto the hydroxide solution. You must have it in a dilute form. I dilute it to about 3.7% so I have plenty of water ready to flush things with. I also like to have a little extra acid to be diluted kept around the lab to get the splashes, if any.

Sodium Hydroxide is far more harmful and quick acting to cause injury than Sulfuric Acid. That is not to say that they are not each dangerous, but the harm from Hydroxide is virtually instantaneous, especially to the eyes, whereas, you have a few seconds to rinse off the acid.

Also, this combination will generate heat but few fumes are given off. This often depends on the floor material.

This combination is also selected to help preserve my floor just in case.

Take care. All is well in my lab this AM. I left the still warm 1 L bottle in its containment bath of cold water overnight just in case. The lid was just a bit loose. So, if the bottle broke the hydroxide would be contained in a diluting water bath and that was in my stainless steel sink. The loose cap would prevent any potential explosive condition in case contaminants had gotten into the hydroxide somehow. It would also protect against a vacuum being created over the hydroxide as air and water vapor condensed as it cooled further.

Rodinal is perfectly safe albeit the solutions are very very alkaline and they must be handled as such. It is the mixers that have to take extra precautions.

PE