I'd like to purchase a tarp as some point, both to put up over a small camp at some point, and to use over a hammock.
When I've camped with my uncle he's used a folded over builders tarp, which has worked so far but I have seen other that have leaked, either 'out of the box' or due to fire damage (hot sparks from a fire causing tiny holes).
What are the characteristics to look out for in a quality tarp, and how can I spot them before I buy them?