I use a metol based ( no Hydroquiononne sp) in the Developer, I place the exposed negative into the developer for about 3 minutes, I then take it out and use a point light source flash
for a second or two and give the whole negative an exposure, then I put it back into the developer and finish as normal.
I use Professor Jolly's method and can give you the formula if you like, just email at bob@bobcarnieprintmaking.ca an I will respond with the exact formula.