As far as sanding goes, on a glass, alum, or copper calls. I only sand them Back N Forth across the call to cut groves in it. On a slate, it really doesn't make a difference which way you scub it, becaise mostly your just cleaning the gunk out of the slate pours and not trying to cut groves into it. It's up to you what grit sandpaper you use, and it depends on how well the call is playing? You can change the tone of a call by using a course or fine grit sandpaper, the finner the grit the higher the pitch the call will be. On slate calls if you use sandpaper I recommend using a fine grit 200 grit of higher, most will use just a green scotch brite pad. On alum or copper I like to use a brown scotch brite pad because it's a little bit courser and scratches it better. I'll also use it on a glass call that I want to kee kee on, it smooths the cuts in the glass out and makes it easier to run a kee kee. It's important to keep your striker tips clean on most woods, some play better dirtier and some won't play at all dirty?
Dodge County NWTF Chapter
WI. Youth Turkey Mentor