That was my first thought having worked with both, Sil by itsself is certainly not sticky, for PU coated fabrics the PU coated side will stick to itself. Not really stick but it won't slide along the same face side easliy. As for Sil tarp, just roll it up and stuff it in a bag. No need to fold and repeated folding will/may break Sil coating down over time if the folds are in the same place time after time....
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