Making Gear: Insulated Pants

The last trip made me realize that I need insulated pants to stay warm when we are winter camping.  I looked around at various options online, but didn't find what I wanted (at least not for what I wanted to pay).  A lot of what was available was heavy gear aimed at skiers and snowboarders - good for what it is intended, but more than I want to carry. I finally decided to make a pair myself.


After some research, I decided to go with synthetic insulation, 4 oz Primaloft Sport.  Down is lighter and more compressible, but it is also a lot harder to work with and with our next trip coming up, I wanted to be able to finish them quickly.  I finally settled on black 1.1 oz nylon (that means that it weighs 1.1 oz per square yard).  Primaloft requires downproof shell fabric, since its fibers tend to leak out of fabric that is more loosely woven.  The nylon met that requirement and it was the lightest fabric I could find without spending three times as much.

I used the Healey Pass Pant pattern from Storm Mountain Designs.  I omitted the patches, pockets, and leg zippers since I wanted these to be as light and simple as possible.  The pattern is not designed to be insulated or lined pants, but it is simple enough to add those things to it.  After further research, I decided to quilt the insulation to the inner shell and leave the outer shell free of them except at the waist and ankle.

I started with the outer shell.  When I cut the pieces out of the nylon, I marked the front pieces with chalk since it would be easy to mix up the front and back pieces.  I did French seams, which are stronger than regular seams, but also require ironing.  Ironing nylon is not something to be taken lightly.  I set the iron on the coolest setting and used a press cloth just to be safe. Once the legs were together, I did a fitting and decided to grade the waist, making it lower in front than in back.  This will allow me to sit down without the back dropping too low or the front bunching up from extra fabric.

For the insulation and inner shell, I cut out the pieces from the nylon again and then pinned them to the insulation.  I then put a line of quilting down the length of each piece and zig-zag stitched around the edges.  Primaloft does not require close quilting, so that should be sufficient to stabilize it.  Once all four pieces were quilted, I assembled them in the same way as I did the outer shell, except I used flat seams instead of French seams.  There was just too much bulk to do French seams.  I put the inner shell into the outer shell and graded the waist.  Then I attached an elastic waistband and used lycra from an old pair of cycling shorts to hem the cuffs.

The finished pants fit well and weigh 11 ounces.  They cost about $60 to make, which is quite a bit less that what I would have spent to buy a pair.

Pictures (click to enlarge):

Cutting out the shell fabric.

 French seams.

Using the inner shell fabric to cut out the insulation.  I discovered after quilting the first piece that I needed to use a lot more pins to keep the nylon from walking all over the place.

A lot more pins.

The insulation after having been quilted.

One of the quilted inner shell pieces.  After quilting, I trimmed away the excess insulation.

Tearing away the scrim.  The scrim is a light fabric that is attached to one side of the Primaloft to make it easier to sew (so it won't get caught in the feed dogs of the sewing machine).  Once it is sewn, it can be removed to make the garment lighter.

The graded waistline.  The front is four inches lower than the back.

The finished product.  They won't win any fashion awards (doesn't everyone need extra padding around their hips?), but they will be warm in camp.