Gravlax still red on skin side after 24h of curing
So, first, I don't think that gravlax looks that bad. Gravlax is never going to be the uniform peach/orange color that cold smoked salmon is (lox).  It just looks a little bit under-cured.

There are two things I do that are different from you, when I make Gravlax:


I cure it for a minimum of 72 hours, turning every 12 hours or so (and pressing the whole time, but that's a texture thing).
My cure includes a couple shots of aquavit.  I find that the alcohol helps the cure penetrate into the center of the salmon.


Here's my recipe.