-huh...  the Durable Water Repelent must lube up the outside of the fabric enough so that the water droplets roll off without breaking the cohesive bonds that keep that droplet too large to pass through the "pores"...kinda like water off a duck's ...   back.   What's the duck do? It keeps it's feathers clean and oiled;but it can grow new feathers to replace broken down ones wheras we must replace the fabric with new when the structure is destroyed. Got it. ("...don't pull the mask off that ol Lone Ranger,...") Thanks. Suppose I can only make the the old stuff work so long untill I turn it into some kind of stiff,heavy ,varnished "oil cloth".  'nuf said.