Can you say more about this? Do you cut the stock made with TEA with however much P.G. and factor that into the dilutions?
IE: 400ml 510-Pyro + 400ml P.G. then 1:50 for 1:100 dilution
Does the P.G. have any effect on keeping qualities?
No, the P.G. is inert.
When the TEA is mixed with water it provides the alkali that activates the developer - the P.G. is fully soluble in water and it is inert. I only add enough P.G. to lower the viscosity of the TEA a little.