Zipper Fly Construction- Underlayer Seam always shows

[Bifurcator]

Hello,
I always struggle with the fly construction.  Right now the biggest issue I always seem to have is the seam at the underlayer (Wearer's right side) always seems to show a little.  I've followed Paulin's book, which has you add an extension to the WR Side- 1/2" width at top of waistband tapering down to 1/4" at end of zipper, which has helped, but I still tend to have the seam show a little.

Paulin's:


My Zipper:


I think part of the problem is the front rise is curved at that area, creating a concave shape, so when it is joined to the other side, both sides are concave and struggle to overlap.  See pattern here:



Any suggestions or tricks to get a nice overlap?  Any books or reference materials that talk more about this?  I've only found Paulin's.

Thanks in advance.

[Gerry]

The following is not necessarily conventional, but it's what I do. Hopefully I've got this right - my brain is a little frazzled at the moment.

Lay the topside pattern so that the fork is on the right and the side-seam on the left, i.e. so that a left-hand-side front is cut from the top cloth (and a right-hand-side front cut from the underside).  Mark an additional  3/8" UNDER-LAP for tucking the fly. Simply draw a line parallel with the fly seam, 3/8ths away and graduate it into the top of the crotch curve (don't extend it all the way). This assumes that a seam allowance has been factored into the draft. If not, the 3/8ths is in addition to any seam you mark.

After cutting through both layers of cloth, remove the 3/8ths excess from the LHS, leaving a 3/8ths under-lap on the RHS only. You need to thread-mark the seamline for transferral to the underside, so that you can correctly align the CF seams when making the trousers.

A fly-bearer will also help prevent the zipper from being exposed.

Edit: looking at the diagram you posted, it follows the same principle? Difficult to tell because the text isn't complete. I'll have to check my book when I have a moment.

[Gerry]

OK, I checked Poulin and I've pretty much repeated what he's said, though I use a greater underlap and graduate the line into the curve rather than ending it abruptly. I also don't taper the line as it descends. That might help in your case. It tucks the bottom of the zip in a way that might feel a little unfamiliar, but it does hide it better.

I never read his section on trouser-making, so I'm glad to see that I'm not alone in doing this! 

Be sure to thread-mark the CF line on each piece, including the seam lines of the crotch curve, so that you're aligning things properly and creating the desired underlap.

[Bifurcator]

Thanks Gerry! Much appreciated.  I think we were doing it almost the same way, but instead of an 1/4" at the bottom it sounds like you have 3/8".  I tried adding that extra 1/8" at the bottom and marking the CF like you mentioned and it helped quite a bit with covering the seam.  Now I'm getting some funky drag lines from the curve and the interior needs some work, but here's the new version:



Curious what your pattern looks like compared to mine, specifically does your zipper placement go into the crotch curve?
Also when sewing the J-Stitch, how do you keep the fly shield out of the way so it doesn't get caught in the stitch?

My construction is a little unorthodox, so that may be the cause of some of my issues too.

[Gerry]

I mark the extension on the cloth, it's not part of the pattern. This is what it would look like, however:



The zipper is taken into the top part of the curve. You can see from my diagram that eventually the seams mirror one another for the main part of the sewing. If you get tension in the curve after sewing, then you might need to stretch the RHS seam a little at the curve using the iron, to allow it to sit flatter.

My fly-guard isn't sewn all the way down the seam. It's 'free' at its base so it doesn't get in the way when topstitching the fly-facing. After stitching the J-curve, a bar tack secures the base of the guard to that of the facing.

You're getting creep from the machine by the look of things, plus some lateral displacement. The LH side's front cloth and fly-facing need to be kept totally flat while sewing. Secure by basting and/or pinning to prevent the two pieces from shifting relative to one another. Press them first then baste along the edge and also just outside of the sew line.

In bespoke it's more typical to pick stitch the fly facing by hand. Not only is it more invisible, but you're less likely to create and trap fullness within the J-curve (as is happening in your photo). Even so, the area still needs basting when hand-sewing, to prevent this problem. Stab-stitch thick areas, and pick normally when/if the cloth becomes more manageable.

If you're going to machine, then it helps to tension the pieces too while you're sewing. Hold the waist from behind the foot and the base of the CF from the front (tricky, but do your best). Now gently pull in both directions with equal force. It has to be equal in order to neutralise the forces (we're not trying to pull the cloth through the machine from behind). This technique takes the give out of both pieces, which helps to prevent creep. Unpick the J stitching of your sample and try again. Press the whole area first and at the very least pin everything. Keep unpicking and practising until you get the hang of things. If it doesn't improve, consider hand-stitching.

I took a look at the last pair of trousers I made where I machined the facing. I didn't know a lot of the above at the time, so had similar issues. Not quite as bad as in your photo, but still not great. Oh well, they're still wearable.

As I mentioned earlier, the base of the fly might feel a little unfamiliar, because you need to reach into it a little more than usual. You get used to it though, and I never have a problem with the zipper showing. I also prefer this method to the usual 'Rob Peter to pay Paul' approach of creating an underlap. It's the first time I've seen it detailed in a book. Good old Poulin!

[Hendrick]

Qustion; do you use metal or other zippers?

Cheers, Hendrick

[Greger]

Practice is part of perfection. Two pieces pulled between the hands and let the machine feed it through.
Jane Rhineharts book has some explanations that has useful knowledge. (Download)
Stanley Hostek has a few books with useful knowledge.
It is interesting that some tailors can have some of the same information that tailors from other regions.

[Bifurcator]

Thank you for taking the time to help me here...

So on your pattern the zipper stops around this area:



Yes, I think stretching the crotch curve straight will help with releasing the tension created from sewing two curves together.

I sewed another mock-up together.  I think I should try straightening the curve where there is a gap in the photo below.  I think when I force that curve to go straight in order to overlap it is buckling the fabric.  In one of my drafting books it instructs to start the front crotch curve as high as possible for a nice shape that wraps around the body nicely, but I don't know that it works for a zipper construction, maybe button fly.  I do worry that straightening that line is going to create an unflattering long straight line, since my waist sits a little higher, but I don't think it's working as it is:







This is probably one of the uglier fly's I've done, but it's defintely overlapping now which is hopeful:



I tried guiding the fabric under to take tension off of it. I also reduced the pressure of my presser foot.  As mentioned I think it's something I need to continue practicing to get better and consistent results.  I do think the shape of my patterns is creating some issues too though- thoughts?

[Bifurcator]

Practice is part of perfection. Two pieces pulled between the hands and let the machine feed it through.
Jane Rhineharts book has some explanations that has useful knowledge. (Download)
Stanley Hostek has a few books with useful knowledge.
It is interesting that some tailors can have some of the same information that tailors from other regions.

I have both of those books/references- I'm going to look through them again as I don't remember seeing/reading that.  Paulin's book is the only one I remember that really talks about adding that extension for the overlap.  It's surprising that more pattern books don't talk about it and how to construct it.

Thanks for the tips!

[Greger]

Its been a while since sewing up a pair of pants. Her book, page 94, explains how she does it. The tailor she learned from probably taught her this method. It explains overlapping by a quarter inch. Bast them together so you can open it up enough to bast the zipper and fly together. Then open it up and sew it a couple of times. After that you can sew below. The way I do it a little bit of "dress" is sewn out.
Where I put the bottom of the zipper is where it ends at the bottom, unless it is too too long. I don't want to waste time with fiddling around with nonsense. Close enough is close enough.
Are you sewing the crotch first? Don't!

[Gerry]

Thank you for taking the time to help me here...

So on your pattern the zipper stops around this area:

What you've drawn is pretty much spot on. Ideally, the zipper comes down as close as possible to the point where the seams equalise in width, but that's not always practical. If things are a little shorter, it shouldn't be a big deal.

Yes, I think stretching the crotch curve straight will help with releasing the tension created from sewing two curves together.

The curves are the same shape, so that's not where the tension arises. It's when the seams are pressed to lay flat that problems can arise, because the hem edges are shorter in length than the seam/sew line over the crotch curve. Subsequently the edges of the seams (and not the crotch curve) may require a little bit of a stretch with the iron to lay properly. The way I do things, the RHS seam is going to be a little fatter at the top of the curve than the seam on the LHS. Therefore it may require a little more work. Merely pressing the seams open will often produce the necessary stretch. However, fatter seams can present more of a challenge; especially in my case because the extended seam isn't 'released' by a cut (as shown in Poulin's diagram), hence the need for a bit of iron work; and also the need to take the zipper down as far as is practical.

I sewed another mock-up together.  I think I should try straightening the curve where there is a gap in the photo below.  I think when I force that curve to go straight in order to overlap it is buckling the fabric.  In one of my drafting books it instructs to start the front crotch curve as high as possible for a nice shape that wraps around the body nicely, but I don't know that it works for a zipper construction, maybe button fly.  I do worry that straightening that line is going to create an unflattering long straight line, since my waist sits a little higher, but I don't think it's working as it is.

I should point out that my image is for a pair of low-rise trousers. So we're not comparing like with like. Early drafts for pantaloons, and modern drafts for low-rise pants, often share the same crotch curving. Typically it's a quadrant (a quarter of a circle), or thereabouts. So the distance between your seat and crotch line is taken out for the width of the front fork extension. Higher-waisted trousers tend to have the curve starting higher up with shaping as demonstrated in Poulin's diagram; and for the reason that you quoted. The higher start to the curve is sometimes mirrored by an extended fork. Either way, it shouldn't present any problem; and if your trousers are higher in rise, stick with it. If in doubt, post a photo of your draft, though I don't make high-waisted stuff so others will be better informed to comment.

Your second sample isn't necessarily as bad as you think. By laying it flat you're forcing a three dimensional object to lay in a two dimensional way. Hence a lot of the stress lines. If you hold the piece up by the waist, allowing the curve to fall backwards as intended - don't forget that the crotch curve passes back between the legs - it will probably look a lot better. Either way, it looks better than the first sample. You're on the right track.

Incidentally, the CF of my pattern looks more angled than it actually is. I drew round the pattern with it at an angle (not intentionally!). There's only a half inch difference in width between top and bottom, so the angling isn't excessive.

[Gerry]

PS When you're pinning, try angling each pin at 45 degrees. Because the pins are on the bias, the cloth will stretch to accommodate their intake, helping to avoid rucks in the cloth and keeping things flat. Also, if you use more pins you can just use their tips. Less intake will again reduce rucks. It can be a little annoying because the pins are more inclined to fall out (take care when taking things to the machine), but it does help.

[Gerry]

PPS If you're not doing so already, press the crotch seam open after sewing, before doing the J-curve.

[Gerry]

The way I do things, the RHS seam is going to be a little fatter at the top of the curve than the seam on the LHS. Therefore it may require a little more work.

Just to clarify, both CF seams end up being pressed open/back by the width of the seam allowance used; so after pressing there's no fatness to speak of on the RHS - a discrepancy is only noticeable prior to pressing. However, due to the way I graduate the the extension into the crotch curve, there's going to be slightly less length along that side's seam edge. So a little more iron work may be required at the curve to get the seam to lay flat as intended.

[Bifurcator]

Thanks for all the tips and advice!  I have a few home projects I need to finish up, but when I have time will try another mock up with the new advice given.  Will update with pictures and thoughts in the next few days. Thanks again!