Peppertoast, whom I strongly suspect is suffering from Winteritis (or is possibly super organized, and planning her summer sewing whilst the snow lays thick outside in freezing Canada) has asked me to describe the square shoulder adjustment I used for the Parfait sundress. Fortunately for me, this is a very easy adjustment.
Here is my square shoulder. It is a rather an extreme example.
I usually adjust for square shoulder in every pattern - my standard adjustment is 5mm, front and back, this amount of adjustment was worked out by trial and error, I do this when cutting out the toile, even for a brand new-to-me pattern line.
The Parfait pattern is nicely drafted, and you can see from this diagram from the instructions that the shoulder is quite shaped, with a strong slope at the shoulder seam of the straps.
I suspect that the Colette patterns are actually drafted for a more sloping shoulder than the big 4 patterns. My suspicion is due to the many changes I made to the shoulder and sleeve of the Lady Grey coat pattern. For this reason, I made a similar amount of adjustment to the Colette pattern pieces as I had in the coat - a 10mm adjustment at the back, and a 7mm adjustment at the front. This is slightly less than the adjustment to the coat shoulder, as the sundress strap is not as wide as the shoulder section of a garment with a sleeve. I admit to eyeballing this adjusted measurement.
According to my Taunton Press "Fitting" book, to adjust for a square shoulder you mark a point the desired distance above the outermost seamline of the shoulder, and rule a line from the neck edge seamline of the shoulder to the marked point.
When preparing this post, I did briefly consider re-doing this properly, but in the interest of truth in blogging (ie laziness) I decided to show you instead the shameful sloppy method that I did use for this particular adjustment, which involves no rulers, and uses the outer edge of the seam allowances as a reference point. I felt that I could get away with this for a mere shoulder strap. I would be more precise if a sleeve or collar were involved.
Even after this adjustment, there is still slope at the shoulder seam. Here is the seam on the toile. You can see that the front strap still angles in towards the neck, which helps keep the strap sitting on the shoulder (this really is a well thought out pattern)
In a standard bodice sloper, a square shoulder adjustment also involves raising the bottom of the armscye, to preserve the dimensions of the armscye. In my personal square shoulder adjustment, I rarely alter the armscye, as I usually need to make a large upper arm adjustment, and the extra 10mm at the shoulder seems to work well with my sturdy mesomorph arms.
In the Parfait pattern, I removed approximately 15mm each at front and back from the length of the straps, shortening the dress between the bust/shoulder blades and the top of the shoulder. This is not a common adjustment for me. I made no alteration to the bodice below the bust/shoulder blades nor at the armscye.
I hope this explanation helps.
Here is a close up of the green target circle print fabric from the lime Parfait for Carolyn. The contrast between the cream background and the green motif is not very clear, I am sorry that I could not get a more clear photo for you. The print is very small, so the fabric reads as a solid unless you are quite close.