I use sheepskin on the Porsche, however, I also use the MF "dread locks" type on lower panels only AND with a different bucket as well. The sheepskin is for top, fender, door etc. The MF is for lower rocker panel area, lower valance etc.
Porsche black is super soft so you really have to rinse often. I rinse with forced water on the mitts after dunking them to loosen any debris in my rinse bucket. If I didn't do this, I found light marring one day due to a small piece of dirt embedded into the mitt. :wall
I gotta get that black sheepskin mitt to match the car.:grinno:
Foam guns or basooka foam is really a good way to flush dirt off first. It's closer to tunnel washing as they used high pressure foam and water to blast off dirt. Some tunnel washes lay heavy foam down in a thick blanket effect, then it passes the high pressure wash area and any physical mops as well. The closer you can get to tunnel washing w/o the physical "touching" the better in release of dirt.
I also find that even after light washing, I have to use an ultra-fine clay to remove debris that did not get taken off by wash. I'd rather clay than risk scratching due to something getting into the mitts.
Also, sheepskin quality varies from mfg to mfg. Some are super soft and thick, others are thinner and a bit more harsh. Some almost resemble a wool cut pad. Stay away from those!! Wool is too stiff for washing. The longer the wool, the better. If it gets matted, brush it out (if you have dogs, a slicker brush works well, then comb it) but if it doesn't get unmatted, toss it, get a new one.
Regards,
Deanski