DraftingFitting, My Bowl

My Bowl

Have you tried copying your true crotch shape? It is quite revealing and may even explain some of your pant fitting issues. There is an easy and inexpensive Aluminium Foil method which I also think of as the “tin foil crotch”.  There are several methods actually and I’ve tried a few in the past.  I wanted to repeat the exercise because I seem a bit befuddled as to how much length I need to cover the undercarriage i.e. the crotch extension length.

For this exercise, I like to use a flexible ruler

and I use small stretchy hair elastics to ‘mark the spot’.  Spots (plural) in this case.  I tied 1/4″ elastic around my waist.  Then slid 5 elastics onto my ruler. (I had to wrap the elastic around the ruler twice to get them to stay in place.) I put one at the zero mark. This is the end that I put on my back at the 1/4″ elastic.  I formed the ruler around my crotch up to my front waist and slid the last elastic up to that point.  The other 3 elastics were moved to sit at my inseam and at the front and back points where my body curves underneath.  I like to double-check everything. So standing in front of the full length mirror, I placed a 12″ ruler between my legs.  Initially it was slanted just like I know that I am.  My undercarriage is not level.  It is tilted towards the back. However, I made the ruler level and moved the 2 elastics marking beginning and end of curve.  It is with relief I can tell you, they didn’t move by much.  I took the curve off my body. Had to do that a couple of times because it would reform.  Finally, I measured how much I needed to bring the marker at the front waist forward so that the ruler could slide down and off without further distortion.

Before starting this exercise, I had cut a square of 18″ wide tissue paper and made an inverted cross (No I’m not a sat*n^st. That’s just the first word that popped in my mind)  Now I placed the formed curve on the tissue with inseam on the upright and curve markers on the cross line.

Did I not warn you this would be revealing?  Before we go further, I see inaccuracy.  I have the curve marks placed about level, when logically the back mark should be lower than the front. The other thing I notice is that I have my front waist lower than my back. Absolutely wrong. Just as my undercarriage dips towards the back, the back waist lowers.  But I know these things, so I think I can work with them. If it becomes too much of a visual distortion for me. I would cut a new tissue, make a new cross and  trace “My Bowl” in a more accurate angle.

First thing that strikes me is how un-U-like I am. When I open a pants pattern and put front and back crotches together, I usually see a big U, sometimes a big and little Ll. In years passed, some patterns would have a V-shaped crotch. (The V never worked for anyone.) According to the visual above,  I am very round. Like a fishbowl.  I am relieved to see that the curve as I marked it is much longer than most patterns allow. I am relieved because I have added as much as 3″ to a pattern to give me enough length.  However, I am not immediately operating on my fitted pants patterns. They fit. Why mess with a good thing?  But I did wonder why they work.  And I think “Bias” is the answer. To my knowledge at this point, a  pants crotch is cut almost entirely on a bias if not true bias. Bias, no matter whether working with stretch or nonstretch fabrics is amazing in its ability to conform to the object (my body) beneath.


So another exploratory exercise that concludes with me not knowing where this knowledge is taking me, IOW what do I do next. But I am relieved to see the shape and the position of the markers. It confirms my actual sewing experience.

3 thoughts on “My Bowl”

  1. This is an excellent tool to have Bev and you’ll be glad of it. If I could offer a suggestion, it would be to mark your hipline on it. This is extremely helpful.

    To do that, tie a 1/4″ elastic around the waist and make sure it’s at your waistline, wherever that falls. Then tie 1/4″ elastic around the body at the point where your leg joins the torso. Make sure it is level all the way around (have DH measure with a tape measure if need be, esp that back and front are same distance from floor). Now, measure from bottom of waist elastic to the hip joint elastic at back and at front. Best to have someone else do this so the numbers aren’t distorted a bit by bending or moving. Measure to the 1/8″ inch if possible and then record those.

    Now, take your ‘bowl’ and measure down that same distance on both Front and Back. Mark. This is your hipline. Draw a line straight across the bowl from front mark to back mark. You now use this line to plot your ‘centre of the body’/inseam line.

    Your centre of the body line will be exactly perpendicular (90 degrees) to this hipline. Clear ruler works great for this. Draw line from your inseam mark all the way to the waistline.

    NOW, to use this bowl, here’s how I do it: Set the bowl on the back pattern piece with the inseam right on the inseam stitching line on the pattern. You will see two things immediately: The waist height on the pant will likely not match yours and your bowl will sit way back into the body of the pant back.

    Let me say first that the grainline on your pants should be true centre. Fold the pant leg at the hem in half, do the same at the knee, matching the inseam and outer seam. Crease along the CF/CB crease line and continue that crease all the way to the waist of the pant. Don’t worry – the inseam and outseam won’t match beyond the knee but that’s fine. Mark that crease onto your pattern piece – all the way from hem to waist.

    Now, as the bowl is sitting on the back pant crotch area, make sure that the ‘centre body’ line on the bowl is parallel to that creaseline/new grainline you marked on your pant pattern.

    Next, adjust the height of the pattern so that the waist height matches yours (on the bowl). If the hipline is marked on the pattern, match those on pattern & bowl too.

    Then lightly trace around the bowl from crotch point to hipline mark on your bowl. Remove bowl. OMG – what a bite that bowl took out of the pant!! If you just cut that as your new centre back seam, the pant wouldn’t fit because there wouldn’t be enough fabric left in the back pant.

    Instead, what I do is to slice the back pant leg right across the crotch line. I mark the crotch line (at the stitching point in the crotch, not cutting line) perpendicular to that new creaseline/grainline. While holding the bowl at the crotch point, move the torso section of the pattern to the the right (or left if you’re working left handed) until the edge of the bowl is sitting on the stitching line of the pant pattern at the point where the pattern curve starts ends and the CB seams starts. This gives you the room your behind needs BUT preserves the rest of the room your body needs. More importantly, I find that it preserves the inner leg seam angle of the original pattern. Now you can trace around the bowl on your pattern piece, from crotch to hipline. Then you add seam allowances and true it up with the Centre back. You’ll probably have quite a job where hipline of the bowl meets pattern but just remember when truing that your body needs quite a slanted CB seam.

    You’ll need to true up the side seam and make a muslin.

    If you find you have too much bagginess in the back under the behind, you may need to pin out a diagonal dart. This is an excellent tutorial on how to do that: http://cationdesigns.blogspot.com/2015/12/that-diagonal-pants-dart.html

    Personally, I’ve not had great success using the bowl on the front pattern piece but I suspect that’s operator error and I’ve just not learned how to do it properly yet. For the back, however, it’s an excellent -and educational, as you say – tool.

    1. WOW thanks! I’ve copied your email and formatted it a bit so I can follow step by step. It will be a few days before I can work with all this information but I definitely will.


  2. BTW, I forgot to add that I trace the bowl & all the markings onto cardboard so it holds its shape when you are using it. I use coloured file folder or poster board because it shows up well when I use it under the paper pattern. (FWIW, I also mark the date and my weight on it – things change~.)

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