Best (ecofriendly) way to waterproof an old (1970s) canvas ridge tent?

Question

I've inherited a 1970s ridge tent which is in good repair but could do with being re-waterproofed. Any suggestions for a cheap/green solution?

Answer 1

wax based seam sealers.  They aren't too expensive.  You can even make a batch yourself.  It just needs to be reapplied every few years.

Answer 2

Baby seal oil is waterproof and biodegradable too.