How about "The leather tanning and quality thread"? Unless somebody has a better idea.
What is your reason for wanting to do that? Not sure about calf, but someone (maybe Ron Rider?) posted pics of a burgundy/#8 shell shoe left in direct sunlight for some period of time. One foot had faded to a brown (not bad looking but definitely faded) whilst the other (not left in the sun) still had the red/eggplant hues and was much darker.
There was a discussion (can't remember if it was this thread or maybe the Alden thread) about this. I asked if it was advisable for me to put my #8 Alden x J.Crew PCT boots in the sun for a few days to see if I could accelerate the "aging" of the colour. I was advised against doing that and should just let time do its work normally. I'm not exactly sure why it was discouraged. Maybe some with more knowledge about leather can chime in.
I'll use this thread to restate a question I previously posted elsewhere to no avail:
Why don't we see any shoes made from elk/moose leather?
Why do we see shoes made from far more exotic leathers, but not from this fairly common and widely hunted animal? I hope that one of the leather/shoe professionals can explain this to me.