10 steps to sew the Merckwaerdigh test bra

In the previous posts I’ve led you through the new Merckwaerdigh e-course for bra pattern drafting to get to this point ; the actual sewing of a bra! Hold on, not yet to wear all day but to test the proportions and support. This is an important step in the whole process  ; test and adjust untill your personal bra fits perfectly. Once it does you can start using the gorgeous fabrics I’m sure you already were tempted to buy. But for a first test it’s better to save them for later and just use different remnants or even scraps (you don’t need much quantity for these small pattern parts). Carefull preparation and the right order of stitching are very important when sewing a bra. When the order is wrong some parts might no longer be accessable.

STEP 1 : Trace the pattern parts very precisely. To stay this accurate it would be best to add the seam allowances around your paper pattern instead of estimate them while cutting the fabrics. For lingerie the seam allowances are much smaller, just 0,75cm and it would be hard to stick to this when you usually add wider seam allowances for other clothing. And there is an easy trick for this; tape 2 regular pencils together and the distance between the points will be exactly 0,75cm!

The picture is not about the test bra obviously but gives a good indication of what I mean. NOTE : don’t add a seam allowance to the fold at the band midfront! And do add information on the pattern parts like which part it is or the stretch direction, in the Merckwaerdigh e-course you will find a lot of tips about this.

STEP 2 : Cut the fabric. Make sure to follow the stretch direction and never ever cut the fabrics on bias, not even the non-stretch cup lining. Because they are all very fine knits the left and right of the bra would shape very differently. The best way of cutting is while the fabric is flat on the table surface. The stretch yarns make it extremely flexible and as soon as you pick it up it will deform. The most accurate way would be cutting with a rotary cutter but scissors could work as well as long as you keep the fabric flat.

STEP 3 : Sew the cup parts. Usually for any bra you would start sewing with the cups. But first thing is to check the needles you use. For stretch fabrics the best sewing needles are the stretch needles. Not regular needles, they are too sharp at the point and could get stuck in the stretch yarns. Not jersey needles, they are a bit too wide at the point and could make holes in the fabric. Stretch needles are just a bit more pointy and above all they have an extra coating which let them slip easily through the stretch yarns.

Before stitching you pin or spray-glue the cup lining to the fabric. Spray-glue will stiffen the fabric somewhat, personally I always use temporarely spray-glue. After a first washing the glue will be gone but the fabric and lining will still stick a bit together and won’t slide away form each other. But the stiffness will be gone. In the test bra is only one seam to sew; the coupe seam. The best way to sew is with a serger but an imitation stitch on a regular sewing machine could work as well. And then topstitch the outer edge with a large straight stitch so it can be removed easily when adjustments are needed.

STEP 4 : Insert the cup in the band. Pin the band on the cup along the underwire seams with the right sides together. Start pinning on both ends and work your way to the centre. Keep in mind the outer edges of the seam allowances don’t have the same length! They are only equal on the stitching line without seam allowance included (= pattern). For the band the seam allowance outer edge will be shorter while for the cup the seam allowance outer edge will be longer. Stitch with a straight stitch at 0,75cm from the outer edge. Stitch with great accuracy right on the stitching line to avoid the cup getting smaller or larger!

STEP 5 : Sew the underwire casing. Now that’s a tricky one! The test bra has a full band which means it’s running all around the body while a raised band will be in 2 separate parts. For a full band you flip the bra to get the cup on top but leave the band hidden behind it. Now first cut the undewire casing at the right length;  ; measure on your band pattern the underwire line + 1cm (to allow a smooth rounding for the casing). Pin the underwire casing on top of the seam allowance at the cup wrong side. Leave at both ends 0,75cm (for finishing the outer seams) and pin from both sides towards the centre. Stitch with a straight stitch as close as possible to the inner edge of the casing. Use a slightly larger stitch than you normally would to get through the underwire casing thickness.

STEP 6 : Finish the band bottom edge with elastic. Before finishing the underwire casing you first have to finish the band bottom edge with picot elastic because you can’t access the bottom edge after the second stitching of the underwire casing. You sew the elastic in 2 steps.
First place the picot elastic over the seam allowance on the right side of the fabric, the picots towards the fabric. Stitch along the picots with a narrow zigzag.
Second turn the elastic to the wrong side and stitch the stretched elastic with a narrow zigzag along the straight length as close as possible to the edge.

STEP 7 : Finish the underwire casing. Put the test bra down with the wrong side up after the elastic has been sewn. Fold the underwire casing flat on the elastic, it will cover the elastic halfway. Stitch the underwire casing with a straight stitch as close to the outer edge as possible.

STEP 8 : Add elastic to the top edges. Now finish the top edges of the bra with picot elastic in the same way as at the bottom edge.

STEP 9 : Attach the straps. Cut the straps elastic in 2 equal parts. Attach a slide on one end of each strap with a narrow zigzag stitch. Push the other ends each through a ring and back through the slide as in the picture. Pin each loose end on the wrong side of the band at the bottom edge at 5 to 7cm from the midback. Sew on with a narrow zigzag stitch at the bottom edge and on the top edge.

STEP 10 : Attach the closure. Slide the band fabric in between the closure layers, stitch with a narrow zigzag stitch with eyes on the left and hooks on the right (left and right as in the way you wear the bra).


For this purpose Merckwaerdigh has developed a checklist you can use in the fitting session for your test bra. I already wrote a blog about this fitting checklist explaning how this works. The Bra Fitting Checklist is also available as a free download to use for any bra you want, even the ones you buy in a shop. You can find it in the list of free downloads on the Merckwaerdigh website.

The Merckwaerdigh e-course Part 1 : the master pattern is now ready! Not yet available though because you can hardly use it without Part 2 : designing. Which I’m still working on right now … More posts about this coming soon!

In the meantime ; since 8th of June 2020 the e-course is READY and available in the Merckwaerdigh shop on the Etsy platform!

For an overview of all the Merckwaerdigh internet activities and the button to subcribe to the Merckwaerdigh Newsletter take a look at www.merckwaerdigh.nl


One thought on “10 steps to sew the Merckwaerdigh test bra

  1. Pingback: How to draft new bra band designs with the Merckwaerdigh e-course | Merckwaerdigh Blog

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