VinceInMT
Subscriber
I don't know what I am talking about except that back in the day when I worked as a drafter I ran lots of blueprints through our machine and the "developer" came from bubbling air through a bottle of an ammonia solution. I remember that the contents of the bottle were quite a bit more concentrated than the household type. A quick look online showed that one can still purchase it (in the states anyway) and it's listed as 29.4%.