FG-7 can probably trace its origin to Champlin 17 which does not appear in Chamlin's book but appeared somewhat later in Minicam magazine in 1940. Dr Lowe of Edwal was not above borrowing formulas. The formula is very simple BUT one of the two developing agents chlorhydroquinone is no longer available.
I looked at the MSDS for FG-7 and at one time Edwal was getting around the lack of availability of chlorhydroquinone by making it in situ by reacting p-benzoquinone (a particularly nasty chemical) with hydrochloric acid. So the original developer can still be made.
FG-7 was one of the most versatile developers. Whether I used it 1:15 with water for slower films or 1:15 with 9% Sodum Sulfite solution for faster films I always got good results. My favorte combination was 1:15 with water with Panatomic-X rated at 64. Grain and sharpness were very good and it had a slight compensating effect too. Apart from these qualities, it had very good shelf life. Edwal ruined the good keeping quality by switching from a dark brown glass bottle to a white nearly translucent plastic bottle. The biggest difference between using it in the early 1970s and using it more recently is that the faster flms are much better. Many developers sold in plastic bottles had keeping problems. These included the many Paterson formulas, the imitation Rodinals and the house brand concentrates. HC-110 is an exception. Even in its plastic bottle it lasts quite a while and PC-TEA also lasts a long time. The current Tri-X, developed in D-76 1:1 gives much better results than Tri-X from the early 1970s developed in FG-7 1:15 with 9% sodium sulfite solution. You can get results which are similar to what FG-7 gave by using Ilford Microphen 1:1, Ilford DD-X, Kodak X-tol, Clayton F60 or any other phenidone based developer. If you want to make up your own stock, PC-TEA will also give similar results at 1:50 and will last a long time.
They made some big claims! I used and liked it back in the day. I thought it could be a bit mushy with the SS but never experimented with varying the quantity. Good shadow detail and I believed it added some usable speed and retained good tonality.
Offer still good?