Over the past few weeks I've started the process of re-dyeing the red leather interior of the car and fixing the cracks and tears throughout. It took a lot of researching and digging to try and find a suitable method that wouldn't damage the leather more, would have the results I was looking for, and would hopefully last.
The leather in my car was faded, and the seats had spots of bad cracking and a few tears, but IMO the leather was saveable. If you want a perfect final result, your only option is to reupholster the interior with brand new leather. I'm not looking for perfect, I'm just looking for a significantly improved appearance while also repairing and reinforcing all of the existing tears and cracks (so the leather doesn't degrade more to the point where reupholstering is the only acceptable option.)
The process I settled on goes something like this:
1) Remove as much of the dirt and old dye as possible by scrubbing the leather with acetone. Once you think it's as clean and dye free as you can get it, scrub it over two more times with acetone. You want as much oil and dye removed from the leather as possible to allow for the new dye to penetrate the leather deeply. Otherwise, it will just sit on the surface and flake off in a short period of time.
(My driveway ended up looking like a murder scene during this process - mountains of dye soaked red paper towels. I found using paper towels was better than using rags, as the dye being removed would quickly clog the pores of the rags.)
2) Once all the acetone has evaporated, use 320 grit sand paper to sand back the deeper cracks to get them as flat as possible. Don't worry about being too aggressive.
3) Once the sanding is complete, repair any tears by gluing in leather backing beneath the tears with leather adhesive. Allow time for the adhesive to fully cure - some can be accellerated using a heat gun.
4) Fill in all cracks with leather filler. Also use leather filler to fill in on top of the repairs made in step 3. Leather filler often comes in various colors. It's ideal to use something similar to the dye you will be using, but it doesn't have to be exact. Leather filler cures quickly with heat, so apply a small amount at a time and cure it with a heat gun. Add more a little at a time, if needed until all the cracks are flush.
5) If you want to retain a leather texture over your filler repairs, you can use a textured leather imprint sheet to create a texture in the top layer of filler as you cure it with a heat gun. If it doesn't come out to your liking, you can always sand it back and try again.
6) Lightly scuff the entire surface you will be dyeing with 320 grit sandpaper.
7) Spray on very light coats of leather dye. Wait at least 10 minutes between coats. Leather dye is not paint; unlike paint which will mainly stay on the surface, the leather dye will permeate the leather. Spraying very light coats will allow the leather to suitably soak up the dye. Heavy coats will result in the dye drying on the surface before it has a chance to penetrate the leather - this will result in peeling. Spray as many coats as needed to get the color you are looking for.
8) Allow to cure for a few days. For high use items like seats or steering wheels, allow the dye to cure for about 2 weeks before handling. After the leather has cured, apply ample amounts of leather conditioner to get the moisture back into the leather that the acetone stripped out. This will prevent the leather from drying and cracking.
My results so far:
The door cards weren't too bad. The drivers side had a few places that needed small amounts of filler, but structurally the condition of the leather was quite good - just faded, especially at the top. I don't have good pictures of what they looked like before, but there are a few shots earlier in this thread where they can be seen.
Immediately after applying the last coat to the driver's door card.
Before shot of the fading and oil staining on the steering wheel. The general condition of the steering wheel was good, so I didn't use any filler.
Driver's door card finished and installed.
Steering wheel finished and installed. I'm going to have to carefully go over the stitching with black dye once the red cures. I couldn't figure out a way to mask off the stitching and still get a good finish on the rest of the steering wheel, so the process of returning the stitching to black will be addressed later . . .
Passenger's door card finished and installed.
Overall shot
Next step is to start working on the seats. Both seats are a lot worse than the door cards and steering wheel. The drivers seat will need a lot of filler. And each seat has a tear that will need to be reinforced, glued, and filled. I estimate each seat will take 1-2 days to complete.
Some before shots of the seats:
I've started on the drivers seat - got about 30% of it scrubbed before I ran out of acetone. I'll update as I make more progress.
