Reply by Dallas

Consider that some of the sand paper may have been damaged by moisture.

I bought about 6 packs of various Gator Grit brand at my local hardware and everyone of them sloughed off the grit very quickly.

I took them back and my friendly hardware guy replaced them.

We looked at the cases and some of them had water damage.

I usually clean up problems like that with a card scraper. Easy to make and leaves an ultra smooth finish.

-- Improvise.... Adapt...... Overcome!