Whenever we have something 'new' we simply spritz the item with water, then take simple dry concrete/plaster mix and sift it on the item with a flour sifter.
You can also use spray adhesive and the dry mix.
Not sure the exact vision of adding the burlap. I personally like JUTE NETTING better than burlap - but thats just my opinion.
The scene sounds cool! Post some pics!
"My day is not complete unless I have terrified a complete stranger!"
Erick James Gyrion
Owner - Oblivion Haunted House