Sewing Men's Slim Trousers in Wool, Leather and Denim: Taper, Ease and Fit

A slim trouser is narrower than a classic trouser along its full length but still falls cleanly from the seat. A skinny trouser follows the leg closely from the thigh to the ankle and usually relies on stretch in the fabric. A tapered trouser can be relaxed through the thigh and then narrow strongly from the knee to the hem.

For woven, non-stretch fabrics such as worsted wool and rigid denim, a slim or tapered cut is the realistic choice. A true skinny cut generally needs stretch denim, stretch wool or a stretch leather.

Ease is what lets you sit, climb stairs and move. Slim trousers reduce it, but cannot remove it completely in a non-stretch fabric.

• Wool suiting with no stretch: keep enough ease at the hip and thigh to sit comfortably; the narrowing should happen mainly below the knee.
• Stretch wool or stretch denim with 2 to 3 percent elastane: hip and thigh ease can be reduced considerably, because the fabric gives when you move.
• Rigid denim: needs similar ease to wool, and it softens and relaxes a little with wear.
• Leather: it does not recover once stretched, so keep slightly more ease than in a stretch fabric, especially across the seat and knee.

In a slim trouser the seat and crotch carry the fit. A crotch curve that is too short in the back creates horizontal wrinkles under the seat and pulls the waistband down when you sit. A curve that is too long gives sagging folds. A flat seat needs less back crotch depth and a shallower curve; a fuller seat needs a longer, deeper back curve and more height at center back.

Make a toile in a fabric with similar stretch and weight, and fit the seat and crotch before narrowing the legs. If the leg is narrowed first, every crotch problem becomes worse, because the leg no longer has room to absorb the folds. A pattern drafted from your own measurements, including the crotch length front to back, is a strong starting point for a close-fitting trouser.

Checking the leg in front of a mirror while walking shows whether the taper pulls. If diagonal wrinkles appear from the inner thigh to the knee, the thigh has been narrowed too much and needs to be released.

1. 1.Mark the knee line on the front and back legs, about halfway between the crotch line and the hem, usually a few centimeters higher.
2. 2.Decide the finished hem width; for a slim men's trouser it usually falls between about 16 and 19 cm across, measured flat.
3. 3.Take the reduction equally from the inseam and the outseam, so the crease line stays centered on the leg.
4. 4.Make the back leg slightly wider than the front at the hem, so the trouser covers the back of the shoe and hangs well.
5. 5.Blend the new lines into the original ones above the knee with a smooth curve, avoiding an angle at the thigh.

The leg opening must still let the foot pass through. In a non-stretch fabric, compare the planned hem circumference with the measurement around your heel and instep with the foot pointed; the hem must be at least that size, or you will need a zip or a vent at the ankle.

Slim trousers are usually worn short, with no break or a light break, so the hem rests just on the top of the shoe or slightly above the ankle. Excess length bunches at the ankle and spoils the clean line. Try the trousers with the shoes you will wear and hem accordingly.

In wool, slim trousers keep classic tailoring details: a fly with a zip, slanted or on-seam pockets, a curtained waistband and a sharp crease pressed along the center of the leg. Choose a crease-holding worsted and press the creases with a damp press cloth.

In denim, the slim leg goes well with jeans construction: flat-felled inseams, topstitched pockets, a yoke and riveted stress points. Use a size 100 or 110 denim needle, a heavier topstitching thread, and a longer stitch. For stretch denim, cut with the stretch running around the body, never down the leg, and sew the main seams with a slight stretch stitch or a narrow zigzag so they do not crack under tension.

Leather trousers are close-fitting by nature and very much part of the trend. Choose a soft lambskin or a thin goatskin around 0.6 to 0.9 mm thick; heavier leather is stiff at the knee and seat. Faux leather on a knit backing is easier to handle and usually has some stretch.

Because pin and needle holes are permanent, fit the trousers completely in a toile before cutting. Cut single layer, wrong side up, with weights and a rotary cutter, and place pattern pieces to avoid flaws and thin areas of the hide.

• Use a leather needle and a stitch length of 3 to 4 mm. Short stitches perforate the leather and weaken the seam.
• Hold layers with clips instead of pins.
• Use a roller foot, a Teflon foot or a strip of tape on the bottom of the presser foot so the leather slides.
• Do not backstitch; tie off the thread ends by hand.
• Flatten seams with a rubber mallet or glue them open with leather cement rather than pressing with steam.
• Line leather trousers with a smooth lining so they slide on and off over the leg.

The closer a trouser fits, the more it depends on the pattern matching your figure. Minerva Patterns drafts each pattern in garment-industry CAD from the measurements you enter, so the seat, crotch length and thigh are built for your body before you start tapering, or you can choose a standard size.

Choose PDF in A4, US Letter, A0 or one long sheet, a projector file, PLT for a plotter or DXF AAMA for pattern software, with or without seam allowances. For leather, a pattern without seam allowances is handy: you can add exactly the allowance each seam needs.