I just went through and read the thread you are talking about....I've made foam decoys in a similar fashion over the last several years, but instead of the mastic compound the writer is talking about in the thread, I use a product called "Kool-seal"...it is used to seal the roofs of mobile homes and such. You can find it at any large home supply store, and runs around (I think) $14/gallon. It is water based clean up as well. I simply brush kool-seal on the foam, put the burlap (or whatever) on the foam, then paint another coat over top. I like to 'double wrap' my decoys (to 'coats' of fabric).
Instead of using burlap, I use old surgical sponges that aren't used, but have to be discarded....they have a loose weave, but are tighter than the burlap shown in the pictures in the thread. I have also used old bedsheets in pinch, so I think it would work for your burlap as well.
Hope this helps you..................
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