So after having mixed hydroquinone and DMSO+glycol and using it for a while longer, I'd live to give a bit further tips. My process specifically was for easy mixing of custom lith developers by using a photo-neutral solution of hydroquinone (that also won't go bad like hydroquinone in plain water would).
1. I mixed a 20g of hydroquinone into 100ml of DMSO, the resulting volume was about 130ml. I added propylene glycol to top up the solution to 200ml, making a 10% weight by volume solution. This was surprisingly easy, requiring no heating or long stirring process. One careful note: add the hydroquinone a little bit at a time or it will clump and be difficult to dissolve. In some tests, I could make a 25% solution of HQ in DMSO, but that was more than I needed
2. DMSO will have some amount of acidic buffering, requiring more alkali to counteract this
3. DMSO will behave (in a lith developer) like a weak form of sulfite. Adjust custom formulas accordingly as needed
4. DMSO forms a complex with hydroquinone and it's radicals. It seems that a high pH, low sulfite formulation with DMSO may produce an alternate developing agent similar to HQMS. It's very difficult to objectively confirm this however, as a home lab user. Suspicions are due to rapid changing in results as solution discolors from clear to yellow to a deep orange, yet remains functional with alkali addition, but at reduced overall contrast (more highlight development) and remains clean working (no fog). Glycol only formulations with HQ will not turn a deep orange like was seen and instead tend to go to brown instead, and give a resulting lack of stability over time. Beaker tests of adding hydroxide to aqueous solutions of HQ-DMSO without sulfite present will give an abnormal progression in color compared to plain HQ. Normally the solution would go yellow (with brown film on top), dark orange, dark brown very quickly. With DMSO, the progression is slower and instead goes yellow (with brown film on top), dark orange, pale brown, at which point it is stable for quite a while. Over several hours it'll decay further to dark brown.
5. DMSO is SMELLY. The smell is regarded as non-toxic and non-reactive, but you'd better get use to it because it gets into every solution your materials touch and is difficult to eliminate without remixing everything for each session. Fixer will become especially smelly. DMSO will evaporate from aqueous solutions. This can be seen by placing covers over trays with DMSO in solution, small droplets of DMSO will be clinging to the covers.
6. I had a hole in a glove that I was using for messing with the DMSO developer solution, so some of the solution got onto my hand. I noticed no change in taste nor smell, and had no notable difference to skin other than my skin becoming a bit slippery due to the alkali in the developer. This seems to indicate that highly diluted DMSO solutions will not retain the skin permeability properties that pure DMSO gives.... but still best to be careful and always use gloves and other PPE as needed. DMSO with hydroquinone specifically should in theory have a bleaching effect on skin, causing whitening. I did not get this effect in my accident.
7. The solution of HQ+DMSO+glycol that I mixed remains stable about 2 weeks later. It is stored in a 1L bottle, with only about 100ml in it. The bottle has not compressed (indicating absorbing of oxygen) nor has the solution discolored or seemed to change in anyway
1. I mixed a 20g of hydroquinone into 100ml of DMSO, the resulting volume was about 130ml. I added propylene glycol to top up the solution to 200ml, making a 10% weight by volume solution. This was surprisingly easy, requiring no heating or long stirring process. One careful note: add the hydroquinone a little bit at a time or it will clump and be difficult to dissolve. In some tests, I could make a 25% solution of HQ in DMSO, but that was more than I needed
2. DMSO will have some amount of acidic buffering, requiring more alkali to counteract this
3. DMSO will behave (in a lith developer) like a weak form of sulfite. Adjust custom formulas accordingly as needed
4. DMSO forms a complex with hydroquinone and it's radicals. It seems that a high pH, low sulfite formulation with DMSO may produce an alternate developing agent similar to HQMS. It's very difficult to objectively confirm this however, as a home lab user. Suspicions are due to rapid changing in results as solution discolors from clear to yellow to a deep orange, yet remains functional with alkali addition, but at reduced overall contrast (more highlight development) and remains clean working (no fog). Glycol only formulations with HQ will not turn a deep orange like was seen and instead tend to go to brown instead, and give a resulting lack of stability over time. Beaker tests of adding hydroxide to aqueous solutions of HQ-DMSO without sulfite present will give an abnormal progression in color compared to plain HQ. Normally the solution would go yellow (with brown film on top), dark orange, dark brown very quickly. With DMSO, the progression is slower and instead goes yellow (with brown film on top), dark orange, pale brown, at which point it is stable for quite a while. Over several hours it'll decay further to dark brown.
5. DMSO is SMELLY. The smell is regarded as non-toxic and non-reactive, but you'd better get use to it because it gets into every solution your materials touch and is difficult to eliminate without remixing everything for each session. Fixer will become especially smelly. DMSO will evaporate from aqueous solutions. This can be seen by placing covers over trays with DMSO in solution, small droplets of DMSO will be clinging to the covers.
6. I had a hole in a glove that I was using for messing with the DMSO developer solution, so some of the solution got onto my hand. I noticed no change in taste nor smell, and had no notable difference to skin other than my skin becoming a bit slippery due to the alkali in the developer. This seems to indicate that highly diluted DMSO solutions will not retain the skin permeability properties that pure DMSO gives.... but still best to be careful and always use gloves and other PPE as needed. DMSO with hydroquinone specifically should in theory have a bleaching effect on skin, causing whitening. I did not get this effect in my accident.
7. The solution of HQ+DMSO+glycol that I mixed remains stable about 2 weeks later. It is stored in a 1L bottle, with only about 100ml in it. The bottle has not compressed (indicating absorbing of oxygen) nor has the solution discolored or seemed to change in anyway
