After another trip to help out at the museum, it occurs to me that others may benefit from my inebriated experience. I am by no means an expert, but I may be able to help someone with the agony of men's breeches.
Breeches are weird. They do not fit like 20th century pants. If the wearer’s pelvis is squeezed and they feel as if they might fall off at any minute, they fit correctly. When working with a commercial pattern, ignore the assembly order and follow these directions instead. Use the pattern directions for making pockets, buttonholes, etc. These tips are most helpful if you have made 18th century clothing in the past.
Start construction with the waist band. Measure the wearer around the top of their pelvis, below the belly and across the small of their back. The back of the waistband should include a one to two inch gap for fabric stretch and weight loss. The waistband should sit low on the pelvis and come up at the back.
When cutting the waist band pieces, make allowance for gut size and the fact that the front might not be horizontal. If the waist band slopes downward at the front, the sides need to be cut at an obtuse angle so the buttons and button holes meet correctly.
The waist band can be finished at this point. Leave some room for the bottom seam, but they can be lined, the buttonholes and eyelets finished, and watch pocket created if desired, but make sure to leave the bottom seams open to accept the legs. Fold the finished waistbands in half and mark the midpoint for attaching to the leg seams later.
Fall front breeches need to have the fall cut through the outer fabric and lining. Complete the fall binders according to the pattern directions and make button holes at the top of the corners. If the breeches are unlined, add fall lining pieces and leave the bottom loose. The bearers can be sewn to the fall opening before it is cut. Since they overlap, the bearers can have a button and buttonhole, if desired. A gap can also be left in the fall seam to button the fall to the waistband buttons.
Now for the hard part: the legs. Most breeches in this period are tight and should fit snugly right under the kneecap. Measure the wearer from the center of the crouch to one inch below the knee. If the wearer’s feet and knees point straight ahead, the pattern pieces need no side adjustment. Most folks are bow legged. If the breeches are to be lined, fitting can be done on the lining and the changes transferred to the fashion fabric. Make sure the pattern has a stand that sticks out on the leg back pieces at the bottom of the outer seam. This is for the buttons. Both front and back leg pieces should also have a tab that hangs down about an inch to support the band. If the breeches are fly front, there should also be a similar stand on the crotch seam of the right front leg piece.
If there is no lining, make muslin fitting pieces of the legs. Make them slightly larger than the pattern. If they are fall fronts, don’t cut the fall. If they are fly fronts, sew the fly seam shut for fitting. The crouch seam should be high, tight, and centered. If the center back pulls, material needs to be added to the top to make the back seam longer. Ignore the back gathers and vent for now. The center front seam may need some adjustment at the top for proper fit.
The bottom seams of the leg fronts should be slightly concave, and just below the kneecap. The rear seams convex, and just above the hollow at the back of the knee. Keep the bottom seam tight to help hold the stockings in place, and follow the knee contour closely. There is not much movement below the knee, but there should be a small pocket above for knee movement. Some breeches have a slightly longer inseam than out.
Once everything in front is nice and snug (looks like the image above) sew the center front and back seams of the outer fabric and any lining. Make sure to leave the top back open a few inches for a vent. Sew the first inch or two of the outer leg seam together, and make pockets, if desired. If making fall fronts, complete the fall lining and finish the fall. If these are fly fronts, make buttonholes and a finish the button stand. Add fly buttons. If making unlined fall fronts, whip the loose bottom of the fall lining to the crouch seam.
Turn the legs and waistband inside out. Match front of the waistband pieces to bearers and pin the fronts of the legs to the finished outer waistband. The waistband should be upside down at this point. There is considerably more material on the waistband front. The back of the waistband should an inch or so longer than the leg pieces at the vent if there is a vent insert. If the vent will be open this isn't needed. Gather the rest to fit. The back should form a moderate bag to sit into. The front of the waistband gets sewn to the bearer pieces. Sew the outer waistband piece to the legs and turn it up. Sew the waistband lining down (don’t sew through the watch pocket.) Add a vent triangle piece if desired, leaving the eyelets free on the outside.
Button the waistband inside out on the wearer and check the fit one last time. If all is well, the bottom of the legs can be trimmed to ½” below the kneecap and just in the hollow at the back of the knee. After any last minute adjustments, unpin and finish the inner leg seams. Finish the outer leg seams as far down as the button stand. Clip the seam allowance into the button stand so it lies flat under the front leg piece. Add buttonholes and buttons in a line that matches the seam above. There may be some excess material at the front, but this will be gathered into the band.
There are many styles of knee band, follow whatever directions come with the pattern. Measure the wearer’s leg just below the kneecap and subtract the button panel overlap—this is the size of the opening the finished knee band SHOULD have for attachment to the leg. Turn under and stitch knee band bottom seam and knee band lining seams (make sure to make a left and right!) The longest part is at the front and gets inserted into a buckle or gets a buttonhole. The back of the knee band is about an inch long and will most often get a buttonhole for a buckle or a button. Finish the sides and top of the knee bands as far as the opening left for the legs (the size of the wearer’s leg measure below the knee.) Clip the outer knee band fabric and pull out the small tab for leg attachment.
Clip the front and back leg bottoms within ¾” to 1” of the outside edge and up to the height of the seam allowance. This will allow the knee band to overlap the button stand on the legs and hold it securely. Pin the knee band upside down, to the bottom of the leg, starting with the long part at the front. Gather or ease any excess leg material into the knee band at the front and sides, to make a kneecap pocket. Sew the seam allowance and turn the knee band down. Sew the lining over the seam allowance, but not to the button tab on the outside of the leg. Instead, sew the loose end of the knee band vertically to the outside of the buttonhole tab. It should look like this.
Fly front breeches are now complete. One last fitting is recommended for fall fronts, to mark the bottom of the fall edges and where the buttons should go. The fall should be tight and not gap too much when sitting.