I'm doing a 6' 4/5 wt flyrod, what are your thoughts on using silk thread? The main reason for this choice is I have the color on hand in silk.

I have used silk thread before from Sunset back in the DAY and had no problems with it.

You need to be aware of one problem that I run into with the silks I use on a daily basis, you can't run them thru the usual tensioner very well, the silk will fray VERY easily. Beleive it or not, I use the "old fashioned way" that is outlined in Dale Clemens book- - - - spool in a shot glass, and run the thread thru the pages of a heavy book, when I need more tension, add a book, you will not have the problem with fraying. It is possible to use a tensioner, (Thompson's) and you can use the one Cabela's sells, but you need to have it released as if you did not have any tension on it at all. Silk is a different animal when it comes to wrapping.. Nylon is round, silk is oval, gotta wrap it easy, not too tight, pack it gently otherwise it will jump on you. But the good thing is that you will have a very nice looking wrap.

Tight lines to all ~~

I have an old Thompson's rod wrapper, so I don't have any trouble with the silk fraying.

I love silk, especially Pearsall's gossamer. I love the ultra-low profile wraps, and the color you get. I have never used CP on it, as I've heard it's prone to blotching with CP. Do be aware, however, that very tightly-packed silk wraps--though beautiful--make it nearly impossible to get your tunnels filled with finish.

I make bamboo fly rods and only use silk thread on them, tho i do have some experience with nylon also, not all bamboo rods were done in silk. I think you will find that silk makes a much better looking wrap than nylon does, especially if you use the smaller diameters. It is different to work with in that it doesn't take kindly to being overworked, lay it down with the wraps as tight to each other as you can in the first place, it will make a better wrap than packing it too much. Burnish it with something round and smooth when you are done and just pay attention to how the finish is going on when you finish it. I have used both varnish and epoxy on silk wraps and have had no trouble with the tunnels not getting enough finish in them, at least not that were because of the material.
john