Soft-tailored Blazer Kit Sew-along

Welcome to our the sew-along for our Soft-tailored Blazer Kit!

We’ve used the same numbering for our sew-along as in the pattern instructions for K3715, our chosen pattern.

We haven’t replaced any of the steps – but we have added details to some of the stages, including photographs where we think they’ll help.

We recommend you follow the pattern instructions which we think are very helpful – but at each stage, check to see if we’ve added anything.

Our collaborator for the Soft-tailored Blazer Kit is Diane at DreamCutSew, who’s provided two additional options for the pattern: a full bust adjustment (FBA) and a buttoned sleeve vent. We’ve inserted links to her website at the points in the construction process where you’ll need to follow the instructions for this additions.

Before you start

Don’t forget to prepare your fabric! We don’t recommend you pre-wash your wool fabric. This is because once your blazer is made up and lined, as with a similar off-the-rack garment, it will need to be spot- or dry cleaned as the lining will respond differently to the wool if washed. Also you’ll have expended some time and effort shaping and fitting your blazer and that fit and shape will risk being lost if washed. However we do suggest you steam your wool gently before cutting. To do this, put your iron on a low steam setting and hold it about an inch away from the fabric for a few seconds until you’ve covered the whole area of the fabric. Allow the fabric to cool and air naturally before starting to work with it.

The following construction procedures are listed in the same order as the pattern instructions, starting with VIEW A and then with Steps 1-5 for VIEW B listed afterwards. Steps 6 onwards apply to both Views.

Pattern alterations

For our kit, Alice created her version of VIEW B, using our ‘Varenna’ silver grey wool. This version has patch pockets. No adjustments were made to the pattern design of fit for her version.

Alice is 5’7″ tall with a 37″ chest and hips. She cut a size ‘M’. As you can see it’s loosely fitted with plenty of room underneath for a pullover.

Diane from DreamCutSew followed VIEW A for her blazer.

Diane cut a more closely-fitted size S for her blazer and made two adjustments to the pattern design as follows:

Full bust adjustment (FBA). This involved adjusting the vertical bust darts and adding a small side bust dart.

Buttoned sleeve vents. This involved the creation of an opening in the side back seam of the sleeve which is then finished with a mitred corner with buttons added afterwards.

Both these adjustments required pattern alterations to be made BEFORE cutting out your blazer. Instructions for making these alterations are on Diane’s DreamCutSew blog post.

Step 1: Interfacing

Your blazer kit contains three different types of interfacing. They’re intended to be used as follows:

Lightweight fusible interfacing (not knit)
Apply this interfacing to the following pattern pieces:

  • 6 – Upper collar
  • 8 – Front facing
  • 9 – Back facing
  • 13 – Pocket welt (View A only)
  • 14 – Pocket flap (View A only)
  • 16 – Top fold of pocket (View B only)
  • We’ll also show you how to use this interfacing to reinforce the hemline of your blazer and sleeves.

Stitch-reinforced fusible interfacing
Apply this interfacing to the two pieces that make up the under collar (Pattern piece 7). These pattern pieces are cut on the bias to help your collar shape and sit correctly; your interfacing should also be cut on the bias.

Interfacing applied to Undercollar on bias (image shows undercollar assembled)

Lightweight fusible knit interfacing
This is a draping interfacing that will add a little structure to the front of your blazer without losing the drape and movement. We recommend applying this interfacing to Pattern piece 1 after sewing the darts in the next stage. The knit interfacing will adjust to the shaping introduced by the darts.

Knit interfacing applied to Front of blazer (after darts sewn)

NOTE: We recommend cutting your interfacing pieces only to the size of the seam allowance of each piece in order to reduce bulk when pressing and finishing

Step 2: Stitching darts

Follow the printed pattern instructions.

Apply the Lightweight fusible knit interfacing to each Front piece (see above) once the darts have been pressed into place. Use a towel under each piece to reduce the heat of the iron and to help follow the shape of the darted front panel.

Step 3: Upper pocket welt

Click here for a full Sew-along of the upper pocket welt.

Step 4 – Stitch side panels

Follow the pattern instructions.

Step 5 – Jetted pocket with flap

Click here for a full Sew-along of the jetted or double-welt pocket with flap

Step 6 – Stitch back

Follow the pattern instructions

Step 7 – Stitch fronts to back

You’ll find that the shoulder seam of the Back pattern piece is very slightly longer than the corresponding Front pattern piece. This is intentional!

Longer shoulder of Back to be eased into Front at shoulder seam
Longer shoulder of Back to be eased into Front at shoulder seam

Use pins to ease the fullness of the Back shoulder into the Front shoulder. This will result in a ‘bulge’ in the upper back of your blazer. That is to accommodate the curve of your shoulder and upper back.

Ease created at back of shoulder
Ease created at back of shoulder

Make sure that you press this area of your blazer over a rolled towel or a Tailor’s ham in order to preserve the shaping and avoid flattening it.

Pressing over a ham
Pressing over a ham

Step 8 – Reinforce neckline

In order to stabilise the curved edges of the neckline and armholes, your kit includes a length of fusible bias tape.

Cut lengths of this tape and use an iron on a medium setting (test first!) to apply this tape to the seam allowance of the armholes and the neckline. The tape is cut on the bias so it will follow the curve of your garment. However the stitched line in the tape will prevent stretching around the curved seams of your garment.

Placing bias seam tape
Placing bias seam tape

Cut it to lengths to fit between existing seams. The stitched edge is placed to the inside of the seam allowance, close to the stitching line. You may need to run a stay stitch over the stitching to secure it in place.

Bias seam tape applied to neckline
Bias seam tape applied to neckline

Step 9 – Attach front facing

Follow the pattern instructions.

Step 10 – Attach side panels to back

Follow the pattern instructions

Step 11 – Assemble collar

Throughout your blazer construction it’s important to take the time to pin, baste if necessary, and stitch accurately. If you follow the stitching lines precisely, with the correct seam allowances throughout, then your collar and lapels will come together properly. There’s no mystery about it – you just need to take your time!

As explained in the Interfacing section above, we’ve provided a special interfacing for the Undercollar. The Undercollar is cut on the bias in order to help it create a nicely rounded shape to support the Upper collar. The stitch-reinforced interfacing adds a little more structure to the Undercollar, but is cut on the bias so that it works with that shaping process.

Grading seam allowance – The pattern instructions instruct you to ‘grade’ your seam allowances when you trim them. This is the process of trimming one layer of a seam allowance more closely than another, in order to help create a smoother appearance on the outside. The seam allowance of the outer or upper layer of fabric is left slightly longer than the one underneath. It’s also why we recommend applying interfacing into the seam allowance; this also helps reduce bulk when you press a seam.

We suggest that after trimming, you press the seam allowances apart on the wrong side of the assembled collar. This will help with a clean finish once the collar is turned the right way out. The narrow surface of a Tailor’s clapper can be used as a ‘mini ironing board’ for this process.

Using Tailor's clapper to press out graded collar seam
Using Tailor’s clapper to press out graded collar seam

Turn the collar out to the right side and press carefully using the lowest steam setting on your iron and a pressing cloth. With your fingers, pinch the seam and roll the seam edge very slightly towards the undercollar in order that the seam edge doesn’t show.

Collar seam rolled slightly under so it's visible only on the Undercollar side
Collar seam rolled slightly under so it’s visible only on the Undercollar side

Step 12 – Attach undercollar to neckline

Follow the pattern instructions, taking your time and using plenty of pins to secure the Undercollar in place. Stitch right to the end of the collar but don’t use a reverse stitch at the end to secure your stitching. Instead, pull a thread through and knot.

Step 13 – Attach back facing

Staystitching – This is the process of running a line of stitching just inside the seam allowance of a pattern piece. It’s usually on an inside curve and prevents a pattern piece from stretching out of shape. When you staystitch the inside curve of the Back facing, don’t straighten it out under your presser foot; follow the curve of the pattern piece.

All you then need to do is pin and stitch the seams that link the Back facing and the Front facing. These are effectively the shoulder seams of the facings.

Step 14 – Attach upper collar to facings

Follow the pattern instructions and as shown there, clip the inside curve of the Back facing (without cutting the staystitching) so that the Back facing can be opened out to match the Upper collar seamline. As with the Undercollar stitching, don’t use a reverse stitch to secure your seam – pull a thread through and knot.

Once this seam is stitched, gently open out your collar and lapel and check that the collar edges and the lapel edges match on each side. If the collar edges or the lapel edges on either side don’t match, then check your seam allowances and correct them if necessary. Also, make sure you’ve stitched the seam right to the point where it meets the collar and lapel seams but no further.

If you need to unpick and go again (you won’t be the first!), we suggest you use a pin or a Tailor’s awl to pull threads out individually – not a seam ripper. It’s worth taking your time!

Don’t press your collar and lapels until you’ve checked they match and you’re happy with their appearance. When you do press, use a cloth and a low steam setting on your iron.

A Tailor’s clapper (or any piece of unfinished wood) can be useful in achieving a flat finish. Just press it down on the garment for a moment or two as soon as you lift the iron off; it will trap the moisture and heat in the garment for a sharper finish.

Step 15 – Stitch neckline seams

This process ensures that the neckline seams are sewn together so that the collar and facings are fixed securely in place. We recommend hand-stitching the seams together – it’s much easier than trying to manoeuvre this part of your blazer into your sewing machine.

Follow the pattern instructions to press open the seams between the Upper collar and the facings, then the Undercollar and the blazer neckline. With the seams opened out, pin the corresponding neckline seams together. Use a slip stitch along the stitching lines to close the gap.

Slip-stitching along the neckline seam lines
Slip-stitching along the neckline seam lines

Step 16 – Assemble sleeves

Follow the pattern instructions. You may find you need to do a tiny bit of easing – simply pinning the pieces together as they curve in your hands will do the trick.

Step 17 – Sew easing stitches in sleeves

Follow the pattern instructions. Don’t forget to leave long ends on your threads! Two lines of easing stitch will help with easing in your sleeve heads.

Step 18 – Attach sleeves to jacket

Start by pinning your sleeve to the jacket from one notch, down the underarm and back up to the other notch. There should be no easing to do here, but it’s important to match the angle of the sleeve seam allowance to the angle of the jacket seam allowance at each stage.

Once the underarm is securely pinned, gently pull on the easing threads to put a some gathers into the top of the sleeve (that’s area we’ll be referring to as the sleeve ‘head’). This easing process creates fullness in the outer shoulder and upper arm area to allow the arms to move and to help the blazer sit well.

In order to distribute this ease, don’t be afraid to use lots of pins! The idea is to prevent creating an actual gather in your stitching, but to gently ease as more fabric from the sleeve than from the jacket, between each pair of pins.

Easing and pinning the sleeve head.
Easing and pinning the sleeve head.

Don’t try and sew over the pins – either pull each one out as you get to it, or baste the seam first. Stitch around the sleeve slowly, following curves and not stretching or pulling the fabric. If you accidentally create a gather, then you simply have to pull out an inch or so of the seam on either side of a tuck then ease the fabric into place, re-pin and re-stitch. As with the collar and lapels, taking your time here will pay dividends with the final finish of your jacket.

Once your seam is stitched, trim the seam between the lower notches in the underarm area, but not in the upper area between the notches. You’ll need the seam allowance in the sleeve head to help with creating structure and shape with the shoulder.

With the sleeve still inside the jacket, press the sleeve seam flat on a board, but only an inch or so into the sleeve. You’re pressing the seam – not the sleeve. This will help even out the eased-in sleeve head into the shoulder seam.

Here you can see how this stage of the pressing process completes the process of easing in the sleeve heads to the jacket. The seam on the right has been pressed, the one on the left has yet to be pressed.

Shoulder seams before and after pressing.
Shoulder seams before and after pressing.

Use a rolled towel or a Tailor’s ham to press the shoulder area and the upper arm area of the sleeve. You’ve created a curved shape and ease of movement there – by pressing it flat you’d lose that shape.

This is where some classic ‘soft tailoring’ techniques will help your jacket shoulders sit well. We recommend you insert your shoulder pads now, instead of waiting until the lining is in place. Your kit also includes two pieces of soft wadding to use as sleeve heads. Both of these will help structure and smooth the shape of your blazer shoulders. Don’t worry – you’re not going to look like Krystle Carrington!

Click here for a full sew-along showing how to attach the shoulder pads and sleeve heads.

Step 19 – Hem blazer bottom and sleeves

Before you hem the sleeves and blazer bottom we suggest you apply some fusible interfacing to the inside edge of the hem. The pattern allows for 4cm hem, so cut strips of your lightweight fusible interfacing (not the knit interfacing) of just under 4cm.

Sleeve hemline with interfaced hem allowance
Sleeve hemline with interfaced hem allowance

Use a cool-medium iron to apply these to the hem allowance bottom of the sleeves and the blazer so that the interfaced edge folds up inside the garment when it’s pressed in place ready for hemming. This will add some gentle structure to the garment edges. Once your hem allowances are in place, we suggest that you use a Blind stitch or a Slip stitch for the hemline rather than a Catch stitch as in the pattern instructions. We find that the fine wool weaves in our blazer fabrics aren’t firm enough to cope with the built-in elasticity of a crossed stitch technique.

Step 20 – Assemble lining

Follow the pattern instructions.

Step 21 – Attach lining to jacket facings

Follow the pattern instructions

Step 22 – Attach shoulder pads

We recommend doing this at Stage 18 (see above) in order to have access to the seam allowance of the sleeves.

Step 23 – Secure and hem lining

Follow the pattern instructions

Step 24 – Topstitching

This is an optional process. As our wools are finely-woven and pressed well, we chose to omit this stage in both our sample blazers.

Step 25 – Add buttons & buttonholes

Follow the pattern instructions (but practice your buttonholes first on an offcut of fabric!) Diane used standard 5-step machine buttonhole for her version of the blazer; Alice used a 1-step buttonhole foot for a buttonhole with a rounded front end. Both worked beautifully on their chosen fabrics.

Finished button and buttonhole
Finished button and buttonhole

We’ve also provided an akyoa shell button to attach to the reverse side of each of your main jacket buttons to give them a neat finish.


Step 1 – Interfacing

As for View A above, applying Lightweight fusible interfacing to upper edge of Pocket – Pattern piece 16.

Step 2 – Stitch darts

As for View B above, applying Lightweight fusible knit interfacing to Front pieces after sewing darts.

Step 3 – attach side panel to front

Follow the pattern instructions

Step 4 – Create patch pockets

Follow the pattern instructions. Don’t forget to snip notches (not just snips) into the curves of the seam allowance of the pockets. This creates room for the fabric in the seam allowance within the pocket when it’s turned the right way out for pressing.

Cut notches into the curve of pocket seam
Cut notches into the curve of pocket seam

Step 5 – Attach patch pockets

When sewing the top-stitched curves on the patch pockets, you may find that an edge-stitch foot makes it more difficult to manoeuvre around the curves. When sewing the curves, try reducing your stitch length as you move into the curve. You may also find you need to stop, lift the presser foot and pivot slightly a few times. Whatever you do, practice first! You’d be amazed at the difference a few practice runs on an offcut can make!

Top-stitched patch pocket
Top-stitched patch pocket

Step 6 onwards

Follow instructions as for VIEW A.

Congratulations! You’ve reached the end of our Sew-along and we hope you now have a blazer you’ll love wearing for many seasons to come!