Cotton mop cover

Washable, reusable....boring but functional.

I didn't have a pattern for this one...I just measured my Swiffer and added enough length to fold over the ends.   It's basically just a long rectangle.  I made a few rows 'ribbed' by crocheting in the back loops, so that it has more scrubbing power.

 
Then I sewed 3 sides closed, and left the 3rd open so that it's easier to get on and off the mop, and added strings to tie it in place.  

I made mine with 100% cotton yarn because I plan to use it wet,
but if you just want to use it dry for dusting hardwood floors, you could also make it with acrylic.