I just sent an abbreviated version of my general process for rehabbing a vintage glove-tanned bag to a TPFer, so I am copying the information here for future reference:
Process for rehabbing an unlined vintage, glove-tanned cowhide
Coach bag (not suede or pebbled or other special, exotic, or delicate leather*):
- If the hangtag is missing, call Coach Coach Customer Service to request a free replacement
- Make sure the bag is clean inside, vacuum it out if it needs it
- Give it a nice long sudsy bath in Ivory or Dawn or Woolite
- Rinse well and let it drain in the sink for a bit
- Stuff it with old towels or clean rags, shape it and set it on a towel to dry (turning occasionally)
- Wait 24 hours and then remove the towels and let it continue drying
- While it is still damp apply a moisturizer like Apple, Leather CPR, Lexol, or Leather Therapy
- Over the next few days, if the leather feels dry or rough or seems to dry out quickly, give it a few more applications of moisturizer. Don't let the moisturizer build-up in the seams and crevices
- When it is dry apply Black Rocks Leather N Rich: use sparingly, work on small sections at a time, wipe off the excess and then buff.
- Give the bag at least 24 hours "to let the leather rest" and give it a second application of Black Rocks if it still looks faded and scuffed.
- Polish the hardware with an appropriate metal polish (e.g., Wenol or Brasso). If the hardware and/or the leather touching the hardware has turned green, search this thread for information on removing verdigris.
- If there has been edging loss from the sides of the straps, touch them up with matching acrylic paint, let the paint dry for 24 hours
- Wear and enjoy a beautifully rehabbed bag!
Note: This is just the process that I have used successfully with several bags - that doesn't mean it is a universal method that will work well on every bag. If you are a new rehabber or if it is an unusual bag and/or has a special problem, it is a good idea to post detailed pictures here to ask for advice from multiple rehabbers. It is also wise to spot-check products in an obscure area before applying it widely to the bag. Good luck, rehabbing is fun but addictive!
*This doesn't mean that delicate, exotic, pebbled, suede or lined bags can't be rehabbed, but they may need special treatment - ask rehabbers here for advice before you begin!