I'm one of those old-timers, I guess. I taught textile science for seventeen years at four different universities. You're using semantics to prove a point, and loving the sound of your own voice. Rayon and Tencel are both synthetic fibers, but not the only ones made from natural resources. They are absorbent. What point are you trying to make? That we deliberately "misinform" others? Or that we believe the books that have been accepted for fifty years in the teaching of textile science?
Please find another board to flaunt your intelligence--you're becoming very tiresome.
Adam, your pants are airy because they don't touch your body as closely as nylons do to mine. If your legs were tightly encased in those pants you would experience the same heat and discomfort as I do in nylons. And that's a fact.
The structure of the fabric does matter, but there are lots of other factors to consider. I teach a class on wool, and pass around a book with more than 30 swatches of various types of wool to illustrate this. There's an enormous difference between a thick wool plush and a very sheer wool voile; both have identical characteristics in the fiber stage, but the fabrics themselves have vastly different characteristics when worn, and that even depends on how the fabrics are shaped to the body, what is worn over or under them, and so on.
So it's a matter of semantics, really. You're right, as far as it goes, but it just didn't go far enough. :)
you've never heard of Gore-Tex? In case you've been living in a cave, Goretex membrane is applied to fabric and moisture vapor moves in one direction, away from the body to the exterior of the fabric.
Actually, Gore-Tex does NOT allow one-way transfer of liquid water or water vapor. What Gore-Tex does do is allow transfer or water vapor _either_ direction, and liquid water in _Neither_ direction. Gore-Tex has very tiny holes in it, holes that are smaller in size than water molecules but larger than water vapor.
That means rain on the outside of a Gore-Tex jacket will stay on the outside (think of kernals of wheat trying to goe through a sieve) while humidity from body perspiration can pass through the jacket (think flour going through a sieve).
This is why the Gore-Tex layer in Polartec Windblock is so nice: the fabric is double faced and can be used either way out, allowing me (and others!) to make two-colour jackets from a single length of fabric! :)
I have some rather glorious royal blue/scarlet stuff in the loft, a delish purple/jade green combination, and a splendid but more muted navy/turquoise one. You can't get these colours in the present range: I've had them 'archived' for a while! KEEP YER THIEVING MITTS ORFF ME STASH! :P
What's misleading here is your definition of breathability. To quote the Gore website:
"Breathability is the rate at which water vapor molecules move through a clothing layer. This movement is determined by the difference in concentration of water vapor (or humidity) between the surface of the skin and the air outside the garment, as well as the physical resistance of the fabric layers. The humidity difference is determined by your activity level, which drives sweating, and the climate around you. The fabric resistance is a property of the materials used in the garment and their thickness. Thicker layers offer more resistance and breathe less."
Breathbility is about humidity, not airflow. Gore-Tex is windproof, but highly breathable.
Gore-Tex is a microporous membrane, as are several other breathable waterproof fabric systems. Gore-Tex prevents the passage of liquid water (so you won't get sluiced down by cold water no matter how much is falling on the outside) whilst allowing the passage of water vapour so that you don't get as wet from sweat as you would, say, in an oilskin. But you won't stay bone-dry. A wicking underlayer will help keep your skin dryer, and of course it is important to wear warm mid-layers as body heat is what vapourises the sweat, driving the water vapour out through the Gore-Tex micropores.
Then there are hydrophilic membranes/coatings, solid synthetics whose material attracts water molecules, which are then driven outwards down the polymer chains by the heat differential between inside and out.
Yet such a tent, if not proofed, would be classed as highly breathable. Ventile cotton, the best breathable waterproof fabric prior to Gore-Tex, is windproof, breathable and waterproof-ish; it will saturate in a downpour and is better suited to snow-and-ice work. (long-staple cotton made into small-diameter threads and very tightly woven. Swells when damp to achieve waterproofing, so not breathable when wet)
I think you are confusing windstopping capability, which you call breathability, with insulation. The slacks will stop the air movement, but not insulate against the windchill. Rohan Airlight and Finelight fabrics are another example: finely woven enough to screen the skin from sun damage, so no air is getting through, but also highly breathable and very cool to wear in summer.
I own a travel towel that is 100% synthetic and very efficient. All modern wicking baselayers are synthetic.
Cotton absorbs and retains moisture, which takes away body heat. Modern synthetic baselayers feel just as good as cotton and transport water without retaining it.
The discussion should be about water droplets and not molecules. Gore company has this to say about "breatheability":
"The GORE-TEX® membrane has 9 billion pores per square inch, with each pore 20,000 times smaller than a water droplet. These tiny holes are too small for water and wind to pass through from the outside, which is how we can guarantee you'll stay dry and warm in a garment made with GORE-TEX® fabric. But these same pores are large enough for moisture vapor to pass through, so your body's perspiration is able to escape and you don't get clammy and uncomfortable. That's what waterproof/breathable' is all about."
Gore-Tex is the other way around. It's an expanded PFTE membrane with micropores that are **larger** than individual water molecules, but **smaller** than a size which would allow for liquid water to penetrate. The Gore-Tex patent probably expired years ago, and there are several other companies producing knock-off expanded PFTE or expanded polyurethane membranes that do roughly the same thing.
That's it. While a DWR treatment theoretically keeps you dry, they stop working at some point when it gets completely soaked. The Gore-Tex (or similar) lining then prevents that large amount of moisture from penetrating. Of course that's when you run into mass loss of breathability and moisture condensing on the inside. I've personally experienced a Gore-Tex jacket feeling clammy inside when the outside got completely drenched. But that's what pit zips are supposedly for.
And just to clear up one of the inaccuracies in this thread.....
Cotton is not a solid fiber. The processed fiber itself is very porous. That's also part of the reason why cotton works so well in towels and takes so long to dry. Synthetic fabrics aren't porous, although there are some that are hollow to increase insulation (like Dupont's Thermax or Holofil). So I guess cotton is theoretically more "breathable" for an equivalent weight or fabric weave. However - I have some really pricey polyester t-shirts that have special weaves to make them very breathable (Under Armour, Nike Dri-Fit, North Face VaporWick, etc).
"Throughout the fiber structure there are variously sized pores or capillary spaces between the variously sized fibrils in each of the six fiber parts. Consequently the cotton fiber can be viewed as a physical microscopic sponge with a complex porous structure. This internal structure makes cotton fibers accessible to liquids and vapors. The capillary action of the fibrils in the fiber pull in the liquids by capillary action where it is held in pores between the fibrils. This accounts for cotton's wickability and its unique absorbing capacity."
The current "wicking" fabrics seem to be primarily microfiber polyester, possibly with additional antimicrobial, antiodor, or moisture management treatments. I'm wearing such a t-shirt right now, and anyone would be hard pressed to tell the difference between this and a cotton t-shirt based on feel or breathability. Of course it listed for over $20, but I got it for under $7 at clearance. The only difference is that it's warmer than cotton when dry (a lot when wet) when layered, dries faster, and feels staticky (I use Static Guard sometimes) at the end of the day.
Since I'm here - any recommendations for resewing a button? Some of my hiking/travel pants have buttons and an elastic hook ring at the cuffs. The original sewing pattern seems to be rather fragile, and it'll just come loose and dangle a half dozen thread ends there. The ring elastic is about 2 mm wide, so the button really needs a little space from the fabric.
Hand sewing needle and thread is your cheapest, fastest option. Put something like a matchstick between the button and the fabric to give the space you need. Double your sewing thread to make it faster - some people here double it again. When you've sewn what you think are enough stitches, wrap the thread around the little shank to strengthen it before taking the thread through to the back of the fabric and securing it with a few stitches.
Yo can put a blob of nail polish on the thread to make it extra-secure. Nail polish will also help to secure the original stitches if you put it on when you first get the garment, thus saving you having to re-sew.
Water molecules are dipoles, meaning charged at one end and oppositely charged at the other end. When water is at liquid temp (and pressure) water molecules form into long chains (think of magnets end to end to end to end). When in liquid state, the chains are too long to "fit through" the tiny holes in Gore-Tex. When water vapor, the molecules are not chained together, and thus water vapor "fits through" Gore-Tex.
To everyone who has contributed to this thread, thank you for expanding my/our understanding. Chemistry and physics are NOT my strong suit, so this has been fascinating to read, coming as it has from so many different directions. I've thoroughly enjoyed this!
Karen Maslowski > "Um... a water molecule is the exact same size whether the water is in >
I think the more traditional definition of "wick" in the cotton industry is of absorption. That isn't the dictionary definition though, which is to "carry away moisture by capillary action".
The "technical" fabrics industry is using the literal meaning of the word. Their "wicking" means a non-absorbant fiber that tends to transport sweat quickly to the surface and dries quickly. I have a closet full of polyester "performance" clothing with trademarks like "WICKed Tee", "qWick-Dri", "VaporWick", as well as CoolMax (DuPont) and DriFit (Nike).
Some of the clothing/fabric companies are using a more descriptive term: "Moisture Management". I've even seen this with several cotton-poly blends.
Depends on the weave and fabric. I have two tight fitting compression shirts with spandex. One is 95% nylon, tighter woven, heavier, and toasty. Great on a cold winter night. The other is a thinner polyester and I can almost feel a breeze.
One of my nylon "travel" pants has a "dobby" weave on the inside. The basic premise is that the raised areas prevent sticking to the skin compared to a flatter weave. Of course on a colder day I've got polypro thermal leggings under them.....
Cotton fiber is not solid and air can pass through the porous fiber. Synthetic fibers typically are solid. I posted this elsewhere in this thread:
Perhaps with all things being equal (same fiber thickness and weave), cotton should allow more air to pass through because the fiber itself is porous. However - my understanding of the new polyester microfibers is that the diameter of the extruded fiber can be considerably less than natural cotton and the finished fabric can breathe well.
You need a spacer laid across the button between the holes. I usually use a straight pin, though for heavy fabric, I may use a round toothpick, and I recall once using the handle of my seam ripper.
When sewing a button on by machine, I was taught to use an old sewing-machine needle, resting the narrow end in the notch in the button foot for light fabrics, and the thick end for heavy fabrics. But sewing a button on by hand is faster, easier, and more secure. (Sewing on twenty buttons, on the other hand . . . )
If there is a large space between the button and the fabric, you need to hold the threads together. The canonical way is to wrap the thread around the stalk.
If the stalk is quite long, as on a heavy coat, I prefer to make a woven bar by working baseball stitch (aka "antique seam") over the two bundles of threads coming through the holes in the button. (If it's a four-hole button, regard it as two pairs, and bundle the threads coming from one pair together.)
The woven bar is quite loppy, however, so the button dangles when not buttoned. The loppiness makes it easier to button the coat, and a woven shank wears better, but you'll want to wind a stiff cone of thread if you are in the habit of wearing the coat unbuttoned. (If you *never* button it, sew the button on flat, with no shank at all.) (And don't cut the buttonholes.)
There is an incomplete discussion of buttons and the like at
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