The annual bowsaw thread usually mentions two points about the
windings used to tension the saw: (1) linen thread is best, and
(2) linen thread is no longer available, because leatherworkers
now use waxed nylon instead of the more traditional waxed linen.

This weekend I stumbled across a source that not only stocks linen
thread in every thickness you can imagine, but does mail order as
well:

        Robin and Russ Handweavers, Inc.
        533 North Adams Street
        McMinnville, Oregon 97128

        (503) 472-5760
        1-800-932-8391

This place mainly caters to weavers, spinners, and other serious
fiberheads, which means that their spools tend to come in one pound
sizes and run around $15 to $20 for linen suitable for use with
bowsaws.  Some thread labelled "10/2 wet spun linen" is about the
same weight as what you would use to stitch leather, and is
unwaxed.  They also had 1 lb spools of "barbour", which is about
1/16" thick, already waxed, and resembles the cord used commonly
for mailed packages about 20 years ago; this stuff looks like it
would be pretty good for bowsaws as well.

I am not affiliated, etc.  My girlfriend occasionally shops there,
and I now have a multiple-lifetime supply of bowsaw thread.

Hope this helps,
Norm W.

Is the linen thread used for cue sticks suitable?  The following link
sells Irish linen in small quantities.

http://www.cuestik.com/

Keith Bohn