Sunday, April 17, 2011

The exception that proves the pressing rule

Mary left a comment on my last post asking why I don't press the seam (attaching the garment piece to facing or lining) before understitching.  Isn't this inconsistent with the usual rule that you must press every seam before going on to the next step?

Great question!  Like Ann (Gorgeous Things aka The Pressinatrix) I am a firm believer in pressing.  During construction.  Pressing while you go makes a HUGE difference to the look of the finished project.  Not pressing will 100% guarantee that your finished garment will look home made in the worst way.  This is why I've invested in a great iron, a ridiculously expensive ironing board, and a lot of pressing equipment.

So yes, Mary, always press a seam before doing anything else to that seam.

Except ... experience tells me that you get a better result if you do not press before understitching, and that in this specific situation, pressing is a waste of time.  They say an exception proves the rule...

Why?  Well, bear with me as I return to the goal of understitching, which is to exactly preserve the shape of the sewn seam by allowing you to easily fold the two pieces along their curved edge.  The finished edge will ideally be perfectly curved with no rippling, unevenness or other distortion, and it will lie perfectly flat with no bulk.

The problem is that the cut edge inside a sewn oval (such as the neck or arm opening) is always smaller than the seam line, as illustrated.  This means the seam allowances have to be stretched (distorted) to be folded back, and will always want to unfold themselves.  They will take the thinner (lining) or shorter (facing) edge with them.

Pressing this edge without understitching just doesn't produce as good a result.  Understitching is more aggressive with the pesky seam allowances than pressing.  It sews them down flat in their stretched position, rather than just folding them back.  Sewing the seam allowances to the lining or facing also firms up the curved edge.

OK, so why not press first and then understitch?  Well, because you just don't need to.  It's an inferior way to achieve your ultimate goal.  And pressing first does not help you understitch.  In fact, it tends to make the job a little bit more complicated.  It's hard to press this type of opening without building in some distortion.  This can be from stretching the fabric as you try to open the curved seam exactly, but more typically in my experience you will find that you have pressed in a fold which is not precisely along the stitching line.  If you are going to understitch (always!) you end up having to correct this fold as you understitch.

So pressing (but ONLY in this one situation) is (1) unnecessary as well as (2) difficult and (3) counterproductive.

Clear as mud?

14 comments:

  1. I've never pressed when understitching. I came across a tutorial that instructed you to press the seam before understitching, and thought what? Surely that would just make it more difficult to understitch? I didn't know why though, it was just a gut feeling that it wasn't a good idea. Your explanation makes it very clear, so thank you! :)
    Ashley x

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  2. I generally don't press before understitching either, but I was thinking about it as I was doing it just the other day. Thanks for explaining the why!

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  3. Very timely post. Last week I was understitching some lapel when this question came to my mind. Thanks for a clear answer.

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  4. Thank you! I was asking myself the same question. I can see that you are right. I know I have distorted a neckilne or two with pressing before understitching.

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  5. Thank you for so generously sharing your knowledge :-) I have learned so much here.

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  6. You just explained why sometimes I'm not happy with my understitching. Thank you for a timely reminder.

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  7. Add me as one that now understands why I'm sometimes unhappy with my understitching. Thank you.

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  8. Thank you very much for taking time to answer my question about understitching. I'm just getting back into sewing (a little more time, a new machine, a renewed interest) after about 15 years away, and I'm learning new techniques from the Internet and expert blogs like this one. I appreciate the time your reply took and your thoughts about this.

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  9. I agree! From my experience too, pressing first creates an unwanted fold that gets in the way of understitching, or worse, the understitching sews the fold in place. Great explanation!

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  10. Kay, that is a very nice dress. I keep teling myself that someday, I'm going to make a sheathe dress but never do. I'm admiring your labels. Would you share the source and the type of label you had made?
    Theresa in Tucson

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  11. I was taught not to do this by a tailor, makes sense. It's just easier not to do any of it.

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  12. Interesting! And makes sense. I've recently tended to press before understitching but have had a niggling feeling that it wasn't the thing to do. You have confirmed that that niggling feeling was correct!

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  13. The only time I sometimes press before understitching is when I'm going to understitch the long straight edge on a collar. Then I'll press the allowances together, then open (flat) then understitch them back together. It seems like I get a better edge that way, but I would never try to press the collar in the finished position before understitching. The last shirts I made for Pearle I wasn't understitching at all, as they were really nice Swiss cottons, and didn't need it.

    Generally though, I would agree with you completely.

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