Sewing - Insulated Pullover

pullover

Features:

Loose in underarms, to avoid contamination from perspiration.
Trim fit in torso.
Double layer insulation in torso (back, front, collar), single layer in sleeves and draft flap.
Uses securely stabilized continuous fiber insulation, thus durable when worn under backpack.
Uses buttons rather than zipper closure, since zippers can fail in field (jam due to fabric caught in zipper; zipper wears out due to abrasion from dirt and then won't close properly; etc). Sometimes zipper failure can be field repaired, sometimes not. Separating zippers difficult to close if hand/arm injured.
Pullover difficult put on or remove with injured arm. Emergency removal with injured arm by cutting front seam.
Collar can be turned under to give more neck ventilation in mild conditions.
Minor cutting/sewing errors no problem, since mismatches easily accommodated in bulky seams.
If lightweight outer shell fabric, wear under spare supplex shirt for protection when bushwhacking and especially when likely to encounter thorns.
Weighs about 360g, assuming shell fabric 1.0 oz/sqyd HyperD diamond ripstop nylon and insulation 2.5 oz/sqyd Climashield continuous fiber polyester, both from RipstopByTheRoll.com.

Pattern:

Similar to shirt pattern, with following modifications: slightly shorter top to bottom; single back rather than cut-on-fold back (easier to cut insulation with single piece); separate front pieces versus cut-on-fold front (allow for front opening); slight curve where shoulder line meets neck (sharp angle doesn't work with insulated garment); sleeve different shape (no need to allow for rolling up sleeve) and size (accommodate insulation); collar completely different (different method of construction); added draft flap. Front and back widths same as for shirt. Since 2 seam allowances on back and each front, plus overlap when sewing up pullover, net effect is circumference reduced by (2 + 2 + 2 + 1) * 3/8" = 21/8" = 2 5/8", or over 3" in practice for shell, plus more to account for bulk of insulation. Result is snug fit in torso, thus reduced convective heat loss due to bellows effect.

pullover pattern

Materials:

2 yards outer shell fabric, at least 60" wide
2 yards inner shell fabric, at least 60" wide
3.5 yards insulation, at least 60" wide
3 x 3/4" buttons
80/12 universal needles
100% polyester thread
Walking foot accessory for sewing machine

Instructions:

Single line of stitching sufficient everywhere, assuming strong thread. No more than single line when top-stitching to stabilize insulation.
Walking foot where specified, otherwise ordinary presser foot.
If shell fabric has right and wrong side, then right and left shell fronts should be mirror images rather than identical. Be careful both when cutting from pattern and when trimming .75" from bottom of inner shell fronts.
Cut outer shell: 1 back, 2 front, 2 sleeve, 1 collar, 1 draft flap.
Cut inner shell: 1 back, 2 front, 2 sleeve, 1 collar, 1 draft flap.
Cut insulation with fiber direction as shown in pattern: 2 back, 4 front, 2 sleeve, 2 collar, 1 draft flap.
Trim .75" from bottom of inner shell and insulation pieces.
Sew together outer and inner shell, right sides facing, 3/8" seam allowance, leave bottom open.
Walking foot. Pin insulation to finished shell, facing inner shell: double layer for back, front and collar; single layer for sleeves and draft flap. Attach insulation using zigzag in seam allowance along closed edge. Zigzag insulation to inner shell along bottom edge. Turn inside out. Fold over excess from outer shell to close bottom and top stitch 3/8". Then continuing top stitch 3/8" from all closed edges.
Walking foot. Top stitch to stabilize insulation. Use only single line of stitching, otherwise shell will bunch up. If thread breaks, seam rip and start over. Verify full bobbin before starting, to avoid having to restart because of running out of thread. Be careful to pull fabric to both sides while feeding through machine, since otherwise bottom shell will bunch up. For back and front, 3 horizontal lines: 8.5" from bottom straight, 16.5" from bottom straight, 5" from top following curve. For sleeves, 1 horizontal line: 12" from top following curve. For draft flap: 1 horizontal line, centered.
Sew together fronts from bottom to middle line of top stitching, right sides facing.
Attach draft flap to inner front, stitching over top stitching of front (so bottom of draft flap coincides with bottom of neck opening).
Attach fronts to back at shoulders, then attach collar and sleeves. Sew up sides of torso and sleeves, with 2" opening at armpits for ventilation and to avoid thick seam junction under arms.
Double fold 1" strip of supplex fabric and top-stitch to form strip 1/4" wide. Cut 3" strips and attach to right side of front opening as button loops. (Lightweight shell fabrics don't give enough stiffness for button loops, so use supplex for button loops even if outer shell not supplex.) Sew buttons to left side of front opening, whatever position gives snug fit.