Nige is right, one way to resolve this gain in contrast is to pre or post flash the paper to lay down a base fog similar to film. Also one can flash in developer so long and the tank is still and the media completely immersed. This helps preserve the (Help, do I refer to them "darks of the neg" or "print highlights") anyway, the partial development of the negative darks before flashing acts as an intelligent mask while flashing. Areas already darkening will resist further flashing, but the white areas do not resist the flash and it is self balancing this way through the midtones.