Boofer, I think the look of the Caerphilly has nothing to do with the cave since, at the time of the pic, it hadn't been in there yet. It's been drying in my cellar at about 65 degrees and 60% humidity (pretty dry here in Montana.) I think the look of the Caerphilly is just the lighting and it looks about the same as all of my other natural rind cheeses at 4 days. There never has been any Geo or PC in my cave since I've never used them.
But about the B linen look of the Gruyere... I had both Limburger and Muenster in the cave but in separate ripening boxes from non-linen cheeses. The only thing I can figure is that I didn't sterilize the mat before I put the Gruyere on it (but that's not like me.) The other thing is that, compared to the Limburger and Muenster, the color and texture of the rind are significantly different. But that, I suppose, could be attributable to the fact that the Gruyere only got infected by wild linens. But it still confounds me since I have six different Asiagos and Manchegos in the cave and they haven't discolored at all.
I run the cave at 53 degress and 83% RH both well regulated with external controllers.
I guess I'll just let it go and see what it tastes like in 6 months. But is there some standard for keeping the cave more sterile? Just curious.