If you make corsets, you will already know that you are making "negative ease" garments from non-stretch fabrics. A corset can be put on because of its busk fastening, and because the amount of negative ease is adjusted with the lacings. But what if we wish to make a garment with no fastening to aid dressing and no lacings to pull in the inches? We make the garment from stretch fabrics so the garment can be stepped into and pulled on... but how much stretch fabric to use? Get out the calculator: it's time for negative ease.

If you have done any regular garment pattern drafting, you know that you take a set of body measurements, then add extra to the measurements to allow for movement when wearing the garment. This is your classic Ease Allowance.

When drafting negative ease, we take away a few centimetres from those "skin fit" body measurements so that the garment will fit snugly against the body, or in the case of foundation shapewear, garments will actually reshape parts of the body (but not perform miracles). In an underwired bra, negative ease is used to spring (pull) open the underwires and to hold the bra band plus wires firmly against the rib cage/chest wall to cantilever the weight of the breasts.

So first we must measure the elasticity of our chosen stretch fabric and remove a calculated amount from the skin fit body measurements to draft a pattern. As we are making a corselette, we will use a fairly strong Powernet (+190g/sm) for most of the figure shaping body of the garment.

Cut a 20cm x 20cm square of your chosen Powernet / stretch fabric, use a pen to mark on it the Warp and Weft of the fabric (Warp runs along the length of the fabric and Weft runs from one selvage edge of the fabric to the other selvage edge - from "weft to right", if you like).

Place one edge of the 20x20 square against a ruler with one corner up to the 0 mark and hold it firmly in position. Now pull the other edge of the fabric from the 20cm mark out along the ruler.

You will reach a point where you will no longer be able to stretch the fabric. This is the fabric's "elastic limit" (the elastic limit of the Powernet in the picture was 28cm weft / 25.5cm warp). You do not want a garment to have the fabric at that extreme of tension, but somewhere between the elastic limit ruler measurement and the 20cm "at rest" measurement is a comfortable, working stretched measurement. You will have to judge the working stretch for yourself (as I do not have your fabric in front of me) but remember two design requirements of this corselette. Firstly, the garment is a shaping foundation garment to smooth out the "lumps and bumps", so there must be a reasonable amount of elastic pull to the fabric when worn. Secondly, the garment is supposed to be put on by pulling the garment up the body, so the waist area of the garment must stretch enough to be pulled over the hips / bottom of the wearer.

You must do this elastic limit test in both the warp and weft directions of the 20x20 fabric square and make a note of the stretch measurements. Do the tests several times to get a good "feel" of how the fabric behaves and its elastic "pull". If you have been following the bra making articles closely, you will remember that some powernets stretch more in one weave direction than the other, and you will also remember that the direction with more stretch goes "around the body" (in industry, the manufacturer of a fabric should supply you with a data sheet with all the fabric's characteristics).

Now for the maths part. We could play the "percentage game" again, but instead we will calculate the pattern measurements using "Scaling Factors".

If we use the measurements of the Powernet in the picture as an example, then the calculations for the Scaling factors (SF) would be:

Weft SF = 20cm unstretched divided by 24.5cm stretched = 0.82 (for around the body)

Warp SF = 20cm unstretched divided by 23cm stretched = 0.87 (for up and down the body)

So if your "skin fit" (natural) waist measurement is 68cm, then

SF 0.82 x 68cm = 55.8cm pattern / garment waist measurement.

If your "skin fit" (natural) hip measurement is 94cm, then

SF 0.82 x 94cm = 77.1cm pattern / garment hip measurement.

If your underbust skin fit measurement is 75cm, then

SF 0.82 x 75cm = 61.5cm pattern / garment underbust measurement.

Remember to put the scaling factor number into your calculator first, then multiply by the skin fit measurement.

After you have made and tried on a few garments, you will gain experience of foundation garment stretch fabrics' elastic pull and understand that the calculated measurements may need some "tweaking". The waist measurement may be a little too tight to pull over your hips, for example, or not tight enough to "control" the waist line. This is all part of the technical fun with creative foundation garment making.

As we are making a corselette (open at the bottom of the garment) we will not need to calculate negative ease for the "up and down" body measurements. If we did, the corselette would just "ride up" and not sit correctly on the body. There would also be too much elastic pull on the stockings. (If we were to make a Panty Corselette, we may use a small amount of negative ease for the "up and down" body measurements.)

Next you need to take a set of skin fit body measurements.

1. Waist

2. Hips (20cm down from waist)

3. Top Hip (10cm down from waist)

4. Around the top of thighs (just under the bottom, or lower, to suit you). Also measure down from the waist to the point around the top-of-thighs measurement.

5. Underbust to waist.

6. Waist to just below the crotch level, or where you wish the bottom hem of the corselette to be at the centre front (1950's corselettes tended to be quite "long in the body").

For the next measurements you need to imagine a side seam line down each side of your body and take the measurements from the lines. (Tip: wear a simple leotard or fitted top that has side seams when taking the measurements).

8. Front Waist.

9. Back Waist.

10 Front Top Hip.

11. Back Top Hip.

12. Front Hips.

13. Back Hips.

Front and back measurements, when added together, should equal the full measurements that you took first, 1, 2, and 3.

Drafting the Pattern

We are going to use your bra pattern draft (blocks with no seam allowance) for the corselette, so you do not need to retake any bust measurements (what do you mean, you have not drafted a bra pattern yet? Read the bra articles and get on with it!)

You only need to draft the cradle and wing blocks without any seam allowance. Draft a three-part cup with 5mm seam allowance. We are using stretch Powernet for part of the cradle, so when drafting the bra cradle there is no need to spring open the underwire, we are just using an underwire to help draft the cradle shape, or you can just use your breast root trace for the cradle shape.

To draft the pattern you will need two sheets of paper that are wider than half your hip measurement and longer than your torso length (unless you are using a computer). Start by drawing a centre front line down the centre of one sheet of paper and copy the bra cradle and wing block onto the centre line at the top of the paper. Measure down from the cradle / cup seam line at the underwire "balance point" / under point of breast point by the "Underbust to Waist" measurement. Square a line across the paper at this Underbust to Waist measurement and mark the line "waist". Square lines across the paper at 20cm down from waist and mark as Hip, 10cm down from waist and mark as Top Hip, around the Top of Thighs from Waist and Waist to just below the Crotch level, or where you wish the bottom hem of the corselette to be at the centre front.

Now for an artistic bit. We will make this corselette with a non-stretch "control panel" at the centre front. I will not give any measurements for this, as the shape of this panel is up to you. You may wish to draw or make a classic curvy panel, as in the diagram, or go for something different such as using straight lines to give a diamond shape on the tummy area (you can do some research and look at images of vintage garments for ideas). Although we are not putting underwires in this corselette, start to draw the panel from the underwire "balance point" on the bra cradle and finish at the below Crotch level line. This control panel can be made from a heavy satin or lace fabric or the same fabric as the bra cups, backing the fabric with a Denier lining fabric to prevent bias stretch.

Calculating the Side Seams 

Next we will calculate where to draw the side seam lines the front control panel into account. Starting with the waistline, measure the width of the control panel at the waistline and take the measurement away from your skin fit front waist measurement. Now multiply the around the body Scaling Factor by the remaining waist measurement, then divide by 2.

Example (based on UK size 12 measurements),

Front Waist = 34cm

34cm – 8.3cm (control panel width) = 25.7cm

SF 0.82 x 25.7cm = 21.1cm

21.1cm / 2 = 10.5cm

Draw a mark at 10.5cm either side of the control panel edge on the waistline.

At Front Top Hip line,

Front Top Hip = 42cm

42cm – 15.4cm (control panel width) = 26.6cm

SF 0.82 x 26.6cm = 21.8cm

21.8 / 2 = 10.9cm

Draw a mark at 10.9cm either side of the control panel edge on the Front Top Hip line.

At Front Hip line,

Front Hip = 45cm

45cm – 7.7cm (control panel width) = 37.3cm

SF 0.82 x 37.3cm = 30.6cm

30.6cm  / 2 = 15.3cm

Draw a mark at 15.3cm either side of the control panel edge on the Front Hip line.

As there is no part of the front control panel at the Top of Thighs level, we just need to calculate the SF for the around the top of thighs measurement and divide it by four.

Top of Thighs = 89cm

SF 0.82 x 89cm = 73cm

73cm / 4 = 18.3cm

Draw a mark at 18.3cm either side of the centre line at the Top of Thighs level.

Now, using a Flexi Curve or pattern drafting curve, draw a smooth side seam curve starting at the bra cradle / wing side seam line and work down through the marks at the waist, top hip, hip and top of thigh levels. When you have one smooth side seam line, copy it to the other side.

The Back Next we need to draft the back panel before we can draw in and true up the bottom hem of the garment. First on the front draft, mark in a half way point on the bra wing bottom hem. Then square a line up from the waistline to this point and measure the length of this line (see pic). We will use this "wing to waist" measurement for the back pattern draft.
On to a new sheet of paper, copy (carbon paper / tracing wheel) from the front pattern the left side seam line, waist line, top hip line, hip line and top of thigh line.
Next draw a line parallel to the waist line at the measurement you took on the front pattern from the waist line to the bra wing bottom hem. Then place your bra wing block (pattern with on seam allowance) with its bottom hemline on this line and with the wings side seam line up against the corselet side seam line. Lightly trace around it.
You now need to reshape the top hemline to touch the top of the corselette side seam. You also may like to lower the centre back of the wing a little and curve the hemline into a "Camisole" style back (more in keeping with 50's style) instead of a "Leotard" bra back.

Calculating the Back Measurements
Turn on the calculator again and work out the back measurements.

Back Waist = 34cm

SF 0.82 x 34cm = 27.9cm

27.9cm / 2 = 13.9cm

Draw a mark at 13.9cm from the side seam line on the waistline line.

Back Top Hip = 46cm

SF 0.82 x 46cm = 37.7cm

37.7 / 2 = 18.8cm

Draw a mark at 18.8cm from the side seam line on the Front Top Hip line.

Back Hip = 49cm

SF 0.82 x 49cm = 40.2cm

40.2 / 2 = 20.1cm

Draw a mark at 20.1cm from the side seam line on the Hip line.

The Top of Thighs level, calculate the SF for the around the top of thighs measurement and divide it by four.

Top of Thighs = 89cm

SF 0.82 x 89cm = 73cm

73cm  / 4 = 18.3cm

Draw a mark at 18.3cm from the side seam line on the Top of Thighs level line.

Using a Flexi Curve or pattern drafting curve, draw a smooth Centre Back seam line curve starting at the bra wing centre back line and working down through the marks at the waist, top hip, hip and top of thigh levels.

The Bottom Hem

We now need to draw in the bottom hem of the corselette.

Place the Back panel block up against the Front panel block with the side seam lines touching at the Top of thigh area. A trick to save you cutting up your blocks is to copy just the bottom halves of the blocks on to new sheets of paper, draw the hemline then copy back the hemline onto the blocks.
You can also "true up" the top hem of the corselette. Again place the back and front drafts together at the side seam lines at the top.
To hold up your 1950's seamed stocking we need to sew suspenders [US: garter tabs] onto the bottom hem of the corselette. On the front draft at the bottom hem, measure half way from the side seam line to the centre front line. Now put a mark 1.5cm to the side of the half way measurement: this is where we will sew on the front suspenders. The 1.5cm position is so that the suspender is not on the centre line of the leg and will not show through your 1950's tight fitting pencil skirt. The back suspenders can go on the half way measurements on the back panel's bottom hem.
As the front of the garment is made of two different fabrics, you will need to split the front draft into the non-stretch "control panel" and the Powernet "front side" panel.
To turn the control panel, front and back blocks into working patterns, add 5mm seam allowance to all three and add pattern marks, make up and identification comments.

As with normal pattern convention you now have only half a garment pattern, so cut a pair of Side Front panels from Powernet and cut a pair of Back panels from Powernet. Cut one Front control panel in outer fabric and one in lining fabric. Also cut a pair of bra cups and linings (if your chosen bra cup fabric needs lining).

Fabrics, Elastics and Findings (the shopping list)

• Non-stretch fabrics for the cups and front control panel
• Strong (190g/sm) Powernet for the body panels (1.5m or 1¾yd)
• Denier lining for the cups and front control panel
• Plush hem elastics, 10 to12mm (½") and 15 to18mm (¾") wide
• Bra strap elastic
• Seam tape (6mm NL2 (¼"))
• Four stocking suspender ends
• Two strap sliders and two strap rings (findings)
• Thread (colour matching or contrasting)
• "Stretch" fabric sewing machine needles

Sewing it Together

Sew together the bra cups following the instructions in the bra articles and put to one side.

Next we will sew together the "body" of the corselette.

As with the bra making we will use a "three step" zig zag stitch for the seams so that they will stretch, unless you possess an industrial "Twin Needle Cover Stitch" sewing machine (lucky you) with the top loopier removed and you are using "Fluffy" Nylon stretch thread in the bottom loopier (no, a overlocker/serger will not do.) 

Set your sewing machine stitch length so that the three step zig zag stitches are quite close together. The stitch length will open out when the garment is stretched and worn.

First, sew the back panels together at the CB (centre back) seam using a straight stitch, then open out the seam allowance and three step zig zag stitch across the seam line. Foundation garment seams need to be "flat" for comfort (no overlocker/serger sewing).

When you have zigzagged a seam you need to "Crack" the seam (sounds painful, but it's how it's described). To crack the seam, go along the seam pulling and stretching the seam and fabric. You will hear the straight tack stitches snapping. The seam will now stretch correctly.
Next, sew the front control panel lining to the front control panel at the CF top hem using a straight stitch; bag out and straight stitch the edges.
Now sew the front control panel to the front side Powernet panels using a straight stitch. I like to sew with the Powernet under the non-stretch fabric as the feed dogs help to pull the Powernet through the machine without stretching. Fold the seam allowance towards the Powernet and sew seam tape over the seam allowance on the inside (see bra making articles for seam tape info). You may like to sew on a Galloon edged lace trim on top of each control panel/Powernet seam on the outside (no trim stitches on the Powernet please) or use a decorative machine top stitch.
When you have sewn the front panels together, sew in the bra cups, cover the cradle to cup seams with seam tape, and again you may wish to apply a lace trim over the top of the seams on the outside (no trim stitches on the cups please). Now you need to sew the bra strap anchor points to the back panels at the top hem. Make up two strap anchors using tape or ribbon and bra strap rings. Thread a length of tape through the rind and sew across the tape next to the ring. You can have a single short length of tape / ribbon for each anchor or go for a Fifties look and have triangle strap anchors (this works better as it spreads the pull of the bra straps out along the top hem). Sew the strap anchors on by placing the anchor on the back panel, right side to right side. When you sew on the plush hem elastic and fold it under, the strap anchors will fold up into their correct positions (see suspender sewing pics for the way to sew on strap anchors).
Sew the back panels to the complete front at the side seams using a straight stitch, then open out the seam allowance, three step zig zag and crack the seams. Next you can sew a 10 to 12 mm wide plush elastic to the top hem/bra cup underarm hems of the corselette. Measure the length of the hem from one cup apex, down the cup underarm hem, around the back, up the other cup underarm hem to the apex. Take away 2.5cm from this measurement and mark the measurement on a length of plush elastic. Use a single step zig zag stitch to sew on plush elastic, working from one cup apex down the cup underarm hem, around the back, up the other cup underarm hem to the apex. Fold under and three step zig zag. See bra making article for full instructions on sewing plush hem elastic. Make up two bra straps as per bra making article instructions, and sew in place.
The bottom hem of the corselette is next, but we need to sew the suspenders [US:garter tabs] in position. Make up four suspenders by threading short lengths of bra strap elastic through the top of each suspender and sewing across. Place each suspender in position, right side to right side of corselette fabric, and tack stitch. When you sew on the hem plush elastic and fold under, the suspenders will go into the right position. This will trap the elastic suspender strap ends between the corselette fabric and the plush elastic.

As with the top hem of the corselette, measure around the bottom hem and take away 2.5cm from this measurement. Transfer this measurement to a length of plush elastic; the plush elastic can be about 15 to 18mm wide.

When you sew the plush elastic on to the hem, overlap the ends of the elastic by 1cm at the centre back seam.

All that is left is to try the corselette on!

To inspire you to experiment more with negative ease for stretch fabrics, here is one of my foundation garment designs. It's an all-in-one long leg strapless panty corselette. There is boning to keep the cups in place, so I have put a hook & eye/zip closure in the centre front control panel so that the garment can be put on.

In the next article I will go over the do's and don'ts of adding more figure control panels to the corselette and other foundation/shapewear garments, plus how to turn the corselette blocks into patterns for a girdle, long line bra and a Merry Widow.