I finally had a chance to do up some line drawings to illustrate the problem with the petal sleeves of the wedding dress I recently altered. There are more pictures in the blog entry Petal Sleeves pt. 1.
The shape of the sleeve pattern adds a lot of extra material under the arm - creating almost a circular sleeve. The hem of the sleeve flapped around like wings. IMO, it wasn't very attractive. Even though the dress was a plus size dress, I can't imagine any woman wanting this style. I find it hard to believe the designer intended this either. I could be wrong since I am not familiar with wedding dress design. I do know that wedding dresses are designed to be easy to alter so perhaps the designer allowed for extra underarm width to accommodate the size of any upper arm. Even so, with the combination of removing excess shoulder height, recutting the armholes and sleeves, the alteration was not that easy. I dare say, it is either sloppy pattern making and/or grading. I would pin the source of the problem on grading from a size 6 all the way into a plus size. I (and Kathleen) have blogged about this many times (search for "Grading is not morphing" at Fashion-Incubator). Plus sizes should have their own patterns separate from Misses sizes. Trying to save time and effort by "grading" patterns from a size 6 up into the plus sizes leads to problems like this. Of course, I don't really know if this is exactly what happened. I would need to look at the whole size range and even the actual pattern pieces to know for sure.
This is what the pattern pieces and fit looked like on the bride before the alteration. The petal sleeve is a regular cap sleeve in the example below. You can see the extra width added at the hem of the sleeve and the wings it creates under the arm.
Below is the shape of the pattern after the alteration. I probably removed a good 1.5" from the sleeve hemline. The fit of the sleeve looked 100% better.
Now if the intent of the pattern maker was to allow the bride to be able to lift her arms for dancing, then it was added in the wrong place. A gusset should be added at the underarm - not the sleeve hemline.