2 October 2019

How to Understitch Like a Pro

How to understitch - Tilly and the Buttons

Do you feel like you need a helping hand with understitching? Well never fear as help is here. It's Nikki here, Product Manager at Team Tilly and in this post I'll be talking you through how to understitch like a pro.

Understitching is a technique used to stop a facing or lining from peeking out from the inside of garments. When attaching a facing or lining to your garment, you can stitch the seam allowances to the facing or lining, close to the seam line, and this will help it stay on the inside where it belongs.

Understitching is one of those nifty sewing techniques that may seem small but makes all the difference to your me-made garments.

If you're the type of person who prefers to learn by watching rather than reading, then you're in luck as we've also made a video to help bring the words in this post to life. Hooray! Tilly has also written a brilliant post where she shares her five tips for neat understitching if you want to get even more tricks and tips, which I thoroughly recommend you check out.

So, how do you understitch?

To prepare for understitching, you need to sew the two fabric pieces together in question, for example the facing or lining and neckline. Sew them together at the seam allowance stipulated in the instructions.

How to understitch - Tilly and the Buttons

Once you've sewn the facing or lining to the other piece, you need to trim and possibly grade the seam allowances. Trimming the seam allowances is as easy as it sounds, and is simply cutting some of the seam allowance away from the seam.

Grading the seam allowances means you cut the seam allowances to different widths to avoid bulky seams showing through to the right side of the garment. If one of the pieces is interfaced, trim that one narrower than the un-interfaced piece. As we need to stitch the seam allowances to the facing or lining, make sure you don’t trim any of the seam allowances less than 5mm (1/4in) wide.

How to understitch - Tilly and the Buttons
How to understitch - Tilly and the Buttons

If you’ve sewed a curved seam you'll also need to clip or notch into the seam allowances before understitching. Clipping and notching the seam allowance will help create a nice smooth curve.

Some people use clipping and notching as interchangeable terms (*cough* I used to do this *cough*), but they are different and either one or the other is used, depending on the type of curve on the pattern piece. If the curve is a concave curve, you need to clip the seam allowance, which means you need to make straight snips up to but not over the stitch line at regular intervals. If the curve is convex, notch into the seam allowance by snipping little triangles out of the fabric at regular intervals.

Once you've clipped or notched the seam allowances (if applicable), we now need to move the seam allowances away from the seam line and towards the facing or lining.

If the fabric is particularly thick or heavy, press the seam allowances and facing away from the seam line with an iron. If the fabric is lighter or stretchy, and can be manipulated reasonably easily by hand, you can use your fingers to move the seam allowances towards the facing or lining. Now obviously, moving the seam allowances by hand isn't going to make them stay put in the same way as with an iron, but if you do this whilst you are sewing (the next step!) then it makes a huge difference.

How to understitch - Tilly and the Buttons

It's now time to get sewing. It might sound counterintuitive but sewing from the right (nice) side of the fabric can get the best results, as you're able to pull the seams taut which produces a neater finish. However, this can make the process of understitching a little trickier as you can't see the seam allowances whilst you're sewing. If you don't feel confident sewing with the fabric facing right side up, you can also sew from the wrong side. It's up to you here! We often show understitching from the wrong side in our instructions as it’s easier to show what we’re doing to the layers. The photos above show examples of understitching from the right and wrong side.

With the facing or lining pressed away from the seam line, and the seam allowances pressed towards them, put your needle in the fabric close to the seam line - about 2-3mm (1/16-1/8in) away. To keep the stitching straight(ish), use the ridge on the presser foot as a guide, or if your machine is able to move the needle to one side, keep the seam lined up with the centre of the foot. Remember, the aim of understitching is to sew the seam allowances to the fabric that will be on the inside of the garment – aka the facing or lining – so double check the seam allowances are pressed in the right direction and that your needle is in the right bit!

How to understitch - Tilly and the Buttons

Making sure you’re holding the fabric taut and away from the seam, sew a line parallel to the seam. Pulling the fabric taut helps keep the seam flat and avoid creating ridges as you sew. I like to sew slowly here and keep adjusting my hands to make sure I’m pulling the fabric away from the seam line at all times.

It’s also worth stopping with the needle down every so often and checking with your fingers that the seam allowances are still pushed to the correct side. As they are narrow and often clipped or notched, they do have a tendency to wander over to the wrong side if left unsupervised for too long.

How to understitch - Tilly and the Buttons

Even though the stitching will only be seen on the inside, try to sew at a consistent distance away from the seam line to get a nice profesh finish. Try not to stray too much away from this distance whilst you're sewing as there's a chance you won't actually be catching the seam allowances as you sew!

How to understitch - Tilly and the Buttons

Press the facing or lining to the inside, rolling the seam line slightly to the wrong side.

And that's it, you now know how to understitch like a pro! I hope you found this helpful, and don't forget we have plenty more video tutorials on our YouTube channel :)

Liked this post? Check out Five tips for sewing a smooth dart - with video!