That makes sense. So I'm indeed using much less overall liquid, and actually I can see some irregularities on the surface.
From my previous experience with other dichromate processes, where I brush sensitized clear gelatin, if I hesitated just a fraction of second while brushing, the first brush strokes would show up clearly as more intense orange patches. You can't notice this on the pigmented carbon tissue, but dry gelatin is very thirsty.
I might try pre-brushing some distilled water (with some acetone, but not too much or it will dry out too fast) in order to get the surface slick and have the dichromate spread more evenly.
I can also try to size my support in two 4% gelatin coats instead of one 8% coat. The thicker gelatin might create a rough surface that compromises the adhesion of the support.
I'm not quite following you on the dichromate amounts. 5ml of 8% concentrate makes 0.4 g of dichromate for your 8x10" sheet, which makes 0.005 g/sq. in - right? I'm using 12ml of 2% solution on a 8x11", which makes 0.0027 g/sq. in, so it has more contrast.
I don't have a densitometer, but I can say my negative is quite thick but not too contrasty.
Thanks for your advice, I'll let you know how it goes.