good string to tie fletching on?

[JackCrafty]

Poly-cotton thread that can be bought at Wally world or any fabric store.  Cheap, strong, and can be glued down with anything.  Nice variety of colors too.  Might be a bit time consuming because the thread is very fine.

[Loki]

The best thread I have found (after silk) is 'Gutermans top stitch' It's thicker than normal cotton which I find far too thin for whipping.

[Cromm]

The best thread I have found (after silk) is 'Gutermans top stitch' It's thicker than normal cotton which I find far to thin for whipping.

That's the stuff I use you can get it in lots of colours and it works real well. Just have to make sure you get the green reel ones for right thickness.

[bow-toxo]

Silk is my recommendation, also.

 Me too.

                                                                   Erik

[Marc St Louis]

There's a couple of things I use.  One that is easy is 100% cotton quilting thread, a bit pricey but very strong stuff.  The other, which I actually prefer but is a pain to get, is the individual threads in baling twine.  You have to cut the twine then pulls out the threads one by one and most are too short to use.  Both are natural fibers