Maybe you can try some gentler color removers (can't be used on some fabrics). I googled "fabric color remover"
Update:
This looks like a great idea. For now, this project has been put on hiatus..................
Because now
I'm dying my 07 Black First, BLACK! I purchased her from RDC not too long ago, and when it came, it had this strange sort of coating. It looked like a waxy gloss. The description said that it had a spa treatment from LMB. I haven't ever sent my bags for a spa treatment before, so I didn't know what to expect.
When the Black First came, it "looked" nice, but overall it was shiny and the waxy stuff that it was treated with started flaking off like dry skin. Now, I don't know if this is the result of LMB's spa treatment, but if so - I will never send my bags in for the spa treatment. It was gross.
Anyhow, once the waxy stuff started flaking off, the black started turning gray. I was really disappointed. I didn't want to sell her on ebay since I knew I wouldn't get any from it (since I'm brutally honest with my listing descriptions), so I decided to dye it.
I don't have any before pictures (I couldn't wait once the Tarrago Black #18 was in my hands), but you can imagine what it was like. Faded (though not due to use) gray, and in some areas, that green color that I hate on black bags.
First, I used a sponge to do the primer all over. All over in the corners, the buckles, everywhere. The idea is to get all the waxy crap off, and the leather as "dry" as possible for the dye.
Then, I applied the first coat. After the prelim coating, it already looked MUCH better. And because it was black on black, it was much easier than the beige on pink. I dyed everything, the handles, the whipstitching, everything but the leather that holds the silver tag.
Second coat: the bag looks like a dream! A damn dream come true! JET black and soft after a bit of use. And I mean JET BLACK.
WILL POST PICS LATER TONIGHT OF THE DARKNESS THAT IS MY BLACK FIRST.