This just in: I am not a complete idiot, nor am I malformed. The problems that plague me when I try to sew pants from many commercial patterns (Simplicity, Butterick, McCall) are not unique. I am not completely inept. I learned this with a trip to Fashion Incubator, a site for those who design for manufacturers.* What a relief!
Kathleen Fasanella discusses common industry problems, researches why they occur, and tells designers what they can do to avoid them. She bought a pair of manufactured pants for her husband, showed that they did not fit, sewed a gusset to make them fit better, and told us why no real human could have worn those pants to begin with. As I understand it, the mistake that makes many pant patterns fit poorly creeps in during the grading, when they enlarge the pattern for different sizes. If the additions are made in the wrong place, a whole set of fit problems can occur. I sort of knew that.
I love knowing what makes clothing work and why. There is even an answer for why the waistbands of pants seem to get smaller at a different rate than the rest of the pants. It's in the cut. If you cut the waistband alongside the pant leg, it shrinks at a different rate than if you cut it across the width of the fabric. It gets smaller faster. It's not my imagination. Henceforth and forever more, I will cut my waistbands across the fabric, even if I have to piece them.
Fitting a pair of pants is indeed almost as complex as, say, rocket science. Weight gain is not evenly distributed. Allowing for weight gain requires knowing where you store it. If, unlike Lyndon Johnson, you store fat above the waist, you've got it made. Folks who store fat in their thighs have one problem. Those who get big middles have another. Each fat storage zone has its own shape, and sometimes the best you can do is to disguise it.
In other words: everything I was ever taught about fitting pants is only partially true. The rules that worked when I was severely underweight don't work now that I am normal and then some. I have curves. They are pleasant, but they are still curves, and pants patterns are designed to fit a median. No, let me correct that. Pants patterns are designed to go on a variety of shapes. They only actually fit one shape well, and the rest of us must learn to put up with what we get, or change brands.
Off I go to fiddle with my stalled pants project. I've also dug out former college level sewing instructor Terry Jones' instructions for making pants. She very kindly posted them years ago during one of my prior rants about pants patterns. Terry Jones can make just about anything seem simple. Her instructions are calm, matter of fact, step by step, and I should have followed them long long ago instead of getting distracted by moving 3 times in 3 years and having sewing machine and fabric out of reach for 18 months.
*Anyone can read Fashion Incubator, but only those who have bought her book may comment on the site. This ensures that she only has to deal with informed commenters. I am grateful and happy to be allowed access to all this inside information.