Guide: Underlining and Interlining

For the purposes of clarity I've isolated this part of the post from the post of July 30 on layout, since the information appears to have been buried too deep in the post. --Marji

For those using a sewn-in underlining for structural support:
Your next step is to cut out and mark your underlining using all the body pieces that will be underlined and not interfaced. This is typically:

1. side back
2. back
3. upper sleeve
4. under sleeve
5. side front (unless you have a welt pocket extending into the side front, in which case you'll be interfacing and not underlining your side front.

I don't cut an underlining for the front, since the whole piece is being interfaced, and the support of underlining and interfacing would be a bit of overkill.

Ann wrote a nice tutorial about a month ago on underlining. I'd like to excerpt her instructions here regarding mounting the underlining to the face fabric.

From Ann:
Attaching the underlining
First - pretreat your underlining. Shrink it before you cut into it, so you don't have a disaster later. Also make sure you cut your underlining on the same grain as the fabric. For precision, use a single layer cutting layout for your underlining. After all, if you're taking the time to do an underlining, you might as well take the few extra minutes to get it perfect, right?

Once it's cut, I attach the underlining to the fabric by hand basting it to the body of the fabric. My basting stitches run parallel to the grain of the fabric. They are 1 to 1 1/2 inches long, and I catch just a thread or two of my shell fabric at each stitch, as you can see here:

This takes time, but it's far superior to basting only at the seamlines, because it structurally reinforces the shell fabric. This is critical for areas that will receive a lot of stress from being bent and sat on, like elbows and rumps. It helps your fabric retain its shape. It's really, really important if you're using a cashmere or fur fabric, which has a tendency to bag out.

Thank you Ann!

Along with her mounting method, I like to stitch along the stitching lines too--which acts as thread tracing as well as holding the two layers together along the stitching lines.

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For those using interlining to add warmth, not structural support:
You may attach your interlining, depending on what it is and how bulky it is, in one of several different methods. If you're just using a layer of cotton flannel I'd be tempted to treat it the same as underlining and use the method outlined above. If you're using Thinsulate or a fleece or lambswool as a layer for warmth, that layer is likely to be bulkier than you'll want in your seam allowances.

Below is a picture of how you may want to insert the interlining to keep it out of the seam allowances. The picture on the far left (in red) is an inside-out illustration of the coat with interlining, sans seam allowances, catch-stitched to the constructed body of the coat. I'd recommend waiting to cut the interlining until after the first garment fitting.

The Complete Book of Sewing

By Constance Talbot

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If you're looking at Paco's tutorial, he's basted the interfacing on using a stitch that holds the interfacing in place securely, and will come out after the garment is stitched together.
If you're looking at Ann's tutorial above, those long stitches only go through the first thread or so, not all the way through, so they don't show on the outside, and those stitches are meant to stay in.

There are more ways than one to do any of these steps. Ann wrote the instructions to mount the underlining using an allover basting stitch that stays in. This is especially relevant in making a coat where there are larger expanses of fabric between seams, or, as Ann noted, when using more fragile fabrics that are more susceptible to deforming. Paco illustrated his jacket using perimeter basting stitches that come out. Both are correct.

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Conclusion:

At this point, you now have all your fashion fabric (coating) fabric cut out and your seamlines marked. Make certain that you also mark your match points, notches, etc., too. I use tailor tacks, or on a cotton underlining a wash-away marking pen for those types of markings. Chalk has limited shelf life for marks, so if you're going to reference the marks in fairly short order, chalk is good too. If your coat pattern included lining pieces, you should have transferred all of your alterations to your lining pieces also.

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As promised - Here is the link to the Flickr set containing all the pictures from today's post. If you're interested in seeing any picture in full size, click on the "all sizes" icon just above any pic, and it'll take you to a larger photo.

I'm out of town now, writing on my laptop in the hotel breakfast room. When I get home I'll take some photos showing how to hold your lapel while padstitching. I'll also get some photos of my underlining mounted to my jacket.