By Will Rietveld, Gossamer Gear Trail Ambassador
A high-end air permeable Gore-Tex or eVent
waterproof-breathable jacket costs $350 or more, and it’s not ultralight; the
lightest one is the Montane Spektr at 8 ounces. A polyurethane laminate rain
jacket costs $150-$200 and is lightweight (down to about 6 ounces) and durable but
not very breathable. Propore jackets are cheap but not very durable. In this
article I will describe how to make a hooded Tyvek jacket plus chaps for under
ten dollars, in a few minutes using a pair of scissors.
The finished Tyvek hooded rain jacket is extra long and weighs just 5.25
ounces. The chaps weigh 2.6 ounces. You may get some comments about the white
color (like “where did you park your space ship?”), but it is actually quite
functional because it stays cooler compared to a dark color.
Tyvek is a spunbonded olefin (http://en.wikipedia.org/wiki/Olefin_fiber)
nonwoven fabric that is made up of millions of polyethylene fibers.
“Disposable” Tyvek clothing”, made of type 1443R soft Tyvek is cheap,
waterproof, somewhat breathable, lightweight, and highly resistant to tears and
punctures. The fabric weight is about the same as silnylon (1.3 ounces per square
yard).
You can use an available Tyvek lab coat as a rain jacket or
windshirt, but it has snaps on the front closure and no hood, which make it
less than ideal. So, the only way to get a hooded jacket with a front zipper is
to purchase Tyvek coveralls and cut them off below the zipper.
The ideal Tyvek coveralls are DuPont “white disposable
coveralls with hood”, style number TY127SWH. These are made of soft 1443R Tyvek
without extra coatings, so it’s lighter weight and more breathable. Disposable
ProShield Tyvek (and similar Tyvek from other companies) coveralls have a
smooth coating on the outside, which makes it look like DriDucks fabric, and it
weighs a little more. The challenge is purchasing a single coverall or two;
most cleaning supply stores sell them by the case of 25. The easiest way to
purchase a single coverall is from Home Depot, but they are the slightly
heavier ones with a smooth outside coating.
Sizing is important; to get a jacket and chaps with long
enough sleeves and legs, and enough room to layer over other clothing, you need
to use coveralls that are two sizes larger than your normal size. I normally
wear a size Large, so I get a 2XL Tyvek coverall. The larger size also provides
extra length so the jacket and chaps overlap. If you only want to make a jacket
you can go with your normal size or one size larger; note that the sleeves run
a little short for a taller person.
The tailoring is so simple that anyone (including me!) can
do it. Here’s the stepwise process:
- Lay the coveralls out flat on a table, front side up.
- Make a mark about 2 inches below the bottom of the zipper.
- Use a pin or other sharp object to puncture the coveralls all the way through to the backside.
- Carefully turn the coverall over and mark the exit point on the backside seam.
- Put the coveralls on and make a mark on one side about 4-5 inches below your waist.
- Take the coveralls off, fold them over, and mark the other side so the two sides are even.
- Draw a smooth concave curve from the center point to side marks on both sides of the coveralls (see photo below, four places total). This will give you a dropped front and tail for the jacket, and raised sides for the chaps.
- Use a sharp scissors to cut on the line all the way around. No hemming is needed since Tyvek does not unravel.
- To make the chaps, cut two pieces of lightweight flat braided cord 30 inches long, then sew the middle of each cord under the folded top edge of each leg of the chaps.
After
making marks on the coverall for the bottom and sides as described above, draw
a smooth line and cut on the line with scissors. This yields a tall jacket and
a pair of chaps. My wife added tie cords at the top of the chaps to tie them to
belt loops, and a couple of pleats on the backside to make them fit
better.
Note that since the front zipper does not separate at the
bottom, the rain jacket needs to be put on as a pullover. To make the garments
completely waterproof, coat the seams with Roo Glue or diluted silicone.
If you wish, you can add a storm flap over the front zipper.
My Tyvek rain jacket made from the Home Depot Tyvek
coveralls weighs 4.25 ounces, and the chaps weigh 2.6 ounces. A rain jacket
made from the lightest soft Tyvek (style number TY127SWH) in size XL weighs
3.15 ounces. Although you get a pair of chaps from this project, my personal
preference is to purchase a pair of Tyvek pants, which I will discuss in a
future blog article. You can also wear very lightweight nylon rain pants, like
the new Montbell Versalite Pant which weighs only 4 ounces.
You are probably wondering how waterproof and how breathable
a Tyvek rainsuit is. I wore the jacket in the shower at home with 30 pounds of
water pressure and it only leaked a little through the front zipper. As far as
breathability, check out the following graph; I just happen to have that data
from a previous project on waterproof-breathable jackets.
Comparative jacket breathability in
terms of accumulated humidity inside the jacket during a sustained 2.25 mile
steady uphill hike and reverse downhill hike. Jackets were completely zipped up
throughout the hike. Note that the Tyvek jacket and DriDucks jacket perform
about the same; they both reach 100% humidity inside after about 35 minutes and
stay steamed up. The lightweight Marmot Essence Jacket (polyurethane laminate)
performed slightly better, about the same as a traditional Gore-Tex jacket
(Montbell Thunderhead Jacket). The more breathable eVent Montane Spektr Smock
(lowest curve) was clearly more breathable than all of the other jackets.
Overall, a Tyvek rain jacket is very easy to make, very
inexpensive, and very durable. Its breathability is about the same as DriDucks,
and not that different from Gore-Tex, which is actually not very breathable.
The white color actually makes a lot of sense since it will be cooler to wear
in the summertime. Happy hiking!
