or... when the wife ain't lookin' 

This stuff is available at your local fabric store. Take a micrometer, and get the thinnest type they have. You might want to take a sample of silkspan along. I don't remember what they call it..."interfacing", maybe . Mike Haverly gave us this info at our September meeting. I guess Mieko sews. He covered his Oriental Plus with this stuff, and it came out fine, tho it's about twice as thick as genuine Polyspan.  Seriously strong covering.  Steve

Steve, I've looked at a lot of nonwoven interfacing.  I had a really hard time finding stuff that was thin and fairly stiff, like the spring undercover.  Depends a lot on the shop and where they get their fabric.  Usually interfacing is made fairly thick to give the fabric some hand.  If you can find what you want, that is great.  A local mattress factory is just another spot to look, if they are using this stuff for the bottoms of their spring.

No problem with recycling, just cut the stuff off before you drop it off.  They won't care.  Nobody should be using a 20 year old spring anyway.  They do wear out.