Eivy Cardigan Sew-Along

Eivy Sew-Along: Interfacing and Overcasting

For the Eivy Cardigan, you need to use interfacing with some stretch to stabilise key areas such as pocket opening, collar and facings.

There are special fusible interfacings for knit and other stretch fabrics, some have stretch in both directions (cross- and lengthwise) and others that only have stretch in one direction.

To learn more about stretch interfacing and the different types, check out our Complete Guide To Stretch Interfacing For Knits.

Can’t get your hands on stretch interfacing? Use lightweight blouse fusible interfacing. Sometimes it has a little crosswise stretch, and if not try cutting the interfacing on the bias to get some stretch.

Do a stretch test before applying the interfacing to the fabric

On a sample, fuse the interfacing to the fabric. Let the interfacing cool an set properly before touching the sample.

Stretch and see that the fusible holds up and that there are no puckering and wrinkles. If it looks good and stretches, you can go ahead and fuse the pieces.

Tip: Use low heat and a press cloth when fusing interfacing to knit fabrics.

Where to apply interfacing

Facings and plackets

  • Fuse the back facing if doing the collarless version.
  • Fuse the front-facing/placket, ideally letting the edge of interfacing extend slightly over the center front fold for a crisp fold. The extension should not be longer than around 6 mm (¼”).

Why: Interfacing facings and plackets give shapes to the garment and prevent it from being stretched out when sewn.


Stabilise the back shoulders using either interfacing with a small amount of crosswise stretch or a fusible bias stretch tape. For more suggestions on how to stabilise shoulder seams see our
Guide to stabilising knit shoulder seams.

Why: Stabilising the shoulder prevents the shoulder seams from growing when sewn and worn.


  • Fuse interfacing to the inner/lower collar piece, having the most stretch crosswise.
  • On supple, soft knits that stretch out easily, also interface the outer collar. In fact, I do recommend interfacing both collars in most cases.

Why: Interfacing the collar adds both stability and shape, which makes it easier to sew and the end result will look more polished.

Pocket openings

Use interfacing on the area of the pocket opening that will be folded and stitched (F or G). Ideally, let the interfacing extend slightly over the fold.

Why: Prevents the pocket opening from stretching out when being stitched over, which is a common issue when sewing stretchy knits, especially if you use a sewing machine.

Bodice and sleeve hems

If the fabric you are using stretches out easily and doesn’t recover its original shape; apply fusible interfacing on the hem to ensure that the area doesn’t expand when sewn and worn.

Overcasting and other edge finishes

Overcasting can keep the edges from curling and prevent sweater knits from unravelling. But usually, there is no need to overcast the edges on most knits fabrics when sewing Eivy Cardigan. However, it provides a nice finish and can prevent the edges from curling.

If you are using a regular sewing machine stitch to assemble the cardigan (i.e. a narrow zigzag stitch), it can be a good idea to overcast using a sewing machine or serger overlock stitch.

Another option is to only overcast the edges of the hem on the bodice pieces, pocket opening and sleeve hem. If you are using a serger, this can also help prevent the fabric from stretching out. Experiment with a higher setting for the differential feed on the serger to see what works best for this purpose.

Fold and stitch method

For a very elegant finish, you can fold in the seam allowance on the facing and stitch over it.

Start by pressing in the seam allowance to the reverse side. To make this easier, use a piece of sturdy paper and draw a line 1 cm (3/8″) in and fold the fabric edge along that line.

Finish by stitching over the folded seam allowance. This provides a high-end finish without the need to overcast.

Hope you found this tutorial useful and also check out the other instalments in the Eivy Cardigan Sew-Along including lots of bonus tips and techniques.


1 Comment

  • Sina Mhinga
    January 25, 2022 at 11:21 pm

    Informative article indeed. I learned a lot. It came just as I was looking for interfacing for knits. Where can I get one at a reasonable price?


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