Waterproof Breathable Fabrics
The term "Waterproof/Breathable" (W/B) refers to any fabric with a PTFE coating
laminated to the inside, that both repels water and moves moisture and vapor
from the inside to the outside. Gore-tex® and Ultrex® are probably the
most known of these types of fabrics.
Terms: First of all, Gore-tex® is a registered trademark
of the Gore Company. There is a tendency to use the term in
a generic sense (as in Kleenex and Xerox) when referring to W/B
fabrics, but this is not correct. There are many brands now
available, that all perform similarly with variations on how waterproof
and or how breathable they are.. There is some debate as
to which brands are better than other brands. This debate
is in the realm of discussions of "micro-porous vapor transfer"
and other fun technical stuff. For the purpose of this page,
I will use the term "w/b" to refer to all types of laminates.
This page,
by Any Mountain, is a good directory to all the different types of coating
and laminates.
3-layer vs. 3-ply: I have frequently heard the terms "ply" and
"layer" misused in reference to w/b fabrics. The term "ply"
refers to thread construction. A ply is a smaller thread that
is used in the making of a bigger thread. A 3-ply fabric
will be constructed of heavier threads than a 2-ply fabric. "Layers"
refers to the layer of laminate bonded to the fabrics. Most w/b
fabrics are 2-layer and require a lining to protect the membrane.
A 3-layer w/b has an additional layer of tricot bonded to the inner
layer, and do not require additional linings.
Linings: I get asked a lot of questions about appropriate
linings for w/b fabrics. If you are unsure, let ready-to-wear
(RTW) be your guide when planning your project. There are
three types of fabric that you can use as lining a w/b garment:
Taffeta, mesh, and various types of fleeces. Taffeta
is slick and slippery. It is inexpensive, and makes it easy
to slide a garment on over multiple layers. The main drawback
I have encountered with taffeta is that it can retain moisture and
become clammy and cool under certain conditions. Meshes,
such as "micro-mesh" seem to hold less moisture than other types
of lining. Many times you will see taffeta and micro-mesh
combined in RTW garments, with taffeta on the sleeves and below
the snow cuff, and micro-mesh in the body of the item. Fleeces
can also work as linings, depending on the purpose of the item.
There are some very nice lightweight 100% polyester wicking
jerseys available, that would be suitable if a little more warmth
is desired. If you want to avoid a lining at all costs, you
will want to use a 3-layer Gore-tex®. Visit sources
page for a list of outdoor fabric sources with internet access.
Seams and seam sealing: You can to do your own seam sealing on w/b fabric, with very nice results. The old stand-by method is to use a seam glue, Seamgrip
being the best product available. It is now possible for home
sewers to use iron-on tape. I have found two types of 1" wide tape: a
clear tape suitable for 2-layer fabric, and a heavier type more suited
to 3-layer w/b fabric. For sources of tape, go to the
sources page and check out the suppliers. You iron the tape directly onto your seam allowance, the goal being to heat the tape enough to bond the tape to the laminate without melting it. Sounds tricky! With a little practice (on scraps, please) you will get the hang of it. Every iron has it's own temperature range, so experiment for the best results. Too hot will melt everything, and too cool won't activate the adhesives for a good bond. I have had the most success using a see-thru teflon press cloth (available from Clotilde Notions) and a 1" thick board, turned on edge, clamped securely, and placed directly under seam. Use a "press and lift" motion, and let each section cool before moving it. Curves are tricky, you may want to use a 'ham' (shaped
pressing form) and experiment with clipping the tape. On curves you can also use a combination of seam glue and tape. For seams, trim the seam allowance to 3/8-1/4", and topstitch to one side. Only use a 100% polyester thread. For more information on thread, visit the Tips page. One other option is to have a partially sewn garment professionally heat sealed. Wy'east Fabrics offers this service; contact them for more information.
Visit the Cascade Layers
site by Rochelle Harper for photos and more tips on using seam tape.
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