Use the dull side of your knife. When you rescrape something, buyers or graders are generally afraid the area you rescraped might be tainted. Most generally if you have leather that has been roughed up by a scraping knife, the hides will grade most usually no better than a slt. damaged. A lot of the time the hide will be graded as a damaged or low grade. When the leather has been roughed from rescraping, it is impossiblr to read the leather of a coon or what ever you scrape. Once you have taken the rag filled with warm water over the roughed area and work the leather over with the rag, you must hang the coon on a nail or something so it will redry. Once you have completed the work and the hide drys, if you have done your woek correct, the hide will look hardly any different than any other well scraped hide. If you get it to wet, you may have to put it back on a strtcher for a day or two. Sometimes when you rescrape the hide, the area that had to be rescraped will be a little damp under the gristle or grease.
One other thing I always do when rescraping coon is, put the hide flat in the freezer untill the whole hide has frozen good and stiff . By doing this you make the areas that are not completly cured the same consistancy as the rest of the hide. I always rescrape coons frozen. If I have 20 or 30 to rescrape, I only take out 2-3 at a time , if that many, because you want the hide to stay frozen while scraping/
One other thing to remember now, the hides are very fragile when dry scraping them, so be very carefull as to not tear them.
It can be done and it can be done nicly, but you must take your time and be patient.