Trench coat interfacing
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Trench coat project part 2: Off-graining and interfacing

The first part of the trench coat project can be found here. The next part of the trench coat project was to off-grain the coat fronts, cut the main parts of the coat and attach interfacings.

Off-graining the coat fronts

Some people were asking for me to explain the off-graining process, so here is a description of what I did. I must warn you that I am not a professional and I only write this down as I have understood it. I recommend using this description as an inspiration only and finding a book written by a professional to learn it properly. One excellent book for this is Couture the Art of Fine Sewing by Roberta Carr. I got this book for myself and it’s full of interesting ways to improve your sewing.


Off-graining is done to allow the coat edge to hang straighter without gaping at the bottom. It is often used in high quality RTW coats and jackets. The basic idea is to cut the front edge slightly off-grain. The exact amount depends on several things: the weight of the fabric and the interfacing, the choice of buttons and buttonholes and even the length of the coat.

The minimum off-graining amount at the waist level is half an inch or 1,3 cm. You add 0,3 – 0,5 cm if you have used “heavy materials”. So +0,3 cm for gabardine (instead of lighter flannel), +0,3 cm for hair canvas (instead of lightweight interfacing) and +0,3 cm for metal buttons (instead of plastic ones). I use gabardine, hair canvas and plastic buttons, so I added 0,6 cm to my 1,3 cm making a total of 1,9 cm at the waist level. In the picture below you can see my front pattern piece in the position where I cut it. The blue line notes the grainline and the original edge position (do not pay any attention to the collar extension at the top). The red line is the edge position after the off-graining.

Image: Off-graining the coat front.

The front facings are also cut similarly off-grain but the other pattern pieces maintain their grainlines.

Interfacing the coat fronts

I used hair canvas to interface the coat fronts. (If you are interesting in the exact material, it is this one from the Lining Company). I catch stitched it in place by hand. The interfacing was cut so that it didn’t go over the seam allowances. I also cut it about 20-25 degrees off-grain to add some stretch to it. My sewing guru Michele recommended 30 degrees, but I didn’t have enough hair canvas to allow that.

Image: Catch stitching the interfacing

Taping the coat edges and the roll line

The next thing to do was to tape the coat edge to have a nice roll line. I used ermazine tape but many tailors seem to use cotton tape like here.

Image: Taped coat edge

The upper 2/3rds of the roll-line of the collar is taped, too The tape is stretched slightly in the middle to shape the roll line. I back stitched at the beginning and the end, did running stitches in the stretched middle section and secured the tape in place using catch stitches. (I hope my sewing terms are okay. Please, correct me, if I’m wrong!)

The back stay

The back stay was made of cheap Ikea cotton that I also used as a toile fabric. I drafted the pattern for it using the back pattern pieces and cut it on bias. The back stay was then machine stitched to the back pieces after the center back seam was sewn.

The back vent interfacing

This coat has also a vent in the back. The vent sides were interfaced using lightweight fusible interfacing:

The pockets

For the place of the pockets I used grey linen holland interfacing that I hand-basted in place. The hand-basting stayed in until the pockets were finished and then I removed the basting and trimmed the extra linen off.

Next time in my trench coat series I will actually start putting the coat together. And I will talk about the sleeves and the various extra piping details I am planning to do.

Thank you for visiting my blog and see you soon! And if you understand Finnish go and check the blog I helped my mom to set up. It is called Pulinaa ja puuhailua. Happy sewing!

Go forward to the part number 3 in the Trench coat series.

I am a mother of two. I sew, knit and create and blog about it.


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