Has anyone used water resistant backing?
 

My husband has requested a picnic blanket quilt. I would like to back it with something that's at least water resistant, has anyone done this? Any suggestions?

My thought is that the quilting might ruin the water proofing... Maybe if I tied it instead of quilting?

Yeah, I think any time you perforate the backing, you're going to lose water proofing. Where (and WHY? lol) are you picnic-ing that it's so wet??

If it were me, I think I'd simply lay a waterproof tarp down first, then my picnic quilt on top.

I can only think of the vinyl fabric used for tablecloth or imitation leather that is sold in the home dec section of JAF or Hobby Lobby. I sewed lunch bags out of the tablecloth fabric. You could always lay out the table cloth face down and then put your quilt or blanket on top. Can't wait until you all have picnic weather !! STAY WARM !!!

I was thinking of using something like the Sunbrella fabric we have on our outdoor furniture... I live in Kansas, and springtime is usually very rainy, so even when you catch a sunny day, the ground is wet!

Here is some information on Sunbrella fabrics; apparently they are "water repellant" not "water proof" and normal use will reduce this feature and requires an application of a water repellant spray. http://www.eastcoastcanvas.com/faq.htm#waterproof

What about that PUL fabric that is used to cover cloth diapers and other baby items? I've seen it at Joann fabrics and sometimes Tuesday morning. Don't know if it is totally waterproof but maybe

I've used flannel backed tablecloth for lawn chair cushions and for baby changing table mat. Neither were quilted.
I've also used thermal backed drapery fabric for a long cloak. Also not quilted. Very warm and keeps the wind and drizzle off. If it gets really soaked in a downpour it does feel wet inside.
Think you would be best to follow the above suggestion to just put a tarp or plastic tablecloth down under your quilt.

I like the PUL fabric idea, that's exactly what I'm looking for! I don't need it to be 100% waterproof, just enough to keep the wet ground from soaking the blanket. And my husband hates using tarps, the blanket always slides off! Thank you!

I would use Crypton fabric if you can find it. It's a special process that makes it almost waterproof. We have a fabric outlet that sells it locally, but you can find it on ebay, or google crypton remnants.