More trouser pattern thoughts

Continuing on with some of the topics that Handmade PHD is attempting to make sense of through exploration...

Side seam length and shape. 

Length- the front and back side seams in her sample trouser pattern should be the same length. In most trouser patterns they are. Is there a time when the lengths could be different? Yes, if it is an intentional design feature, or sometimes for shaping. (see calves below).

But,,,,In general, the side seams do not have to be the same shape at all. Especially from teh knee up to the waist.

Picture here shows a 1950's German draft, a 1920's draft and a 1970's draft for men's trousers.

 

Sometimes they are the same shape - as is the case of pyjamas or the flat block referenced in the previous post

If you do a bit of research you can see that traditionally men's trouser draft will not have the same outseam shaping on the front and back. The waist to hip ratio for men is generally less than for women but we must remember that shaping needs to reflect the body, and the body shape needs to be accommodated regardless of gender. If the hip is not full at the sides, there is no point to putting the shaping there. If it works for a particular body shape -great- but it is not the only way, nor necessarily the best way to go about it.

 

Side seam shape- if the outseams of a trouser are the same shape, or almost the same shape the trouser block could have been developed from a skirt pattern

  Patterns shown here from More Dress Pattern Designing by Natalie Bray.  

This shape of pattern development was very common in the days when trousers were more of a novelty garment for women. It puts more waist suppression in the side hip area, and the patterns tend to have a straighter CB seam angle (smaller amount of waist suppression). It is certainly much more common practice in women's patterns then in men's.

Inseam length.

The inseams from hem to knee in her sample trouser pattern should definitely be equal on the front and back panel. I'd argue for them to be equal completely but there are bigger issues with the drafting here.

The back inseam from knee to the tip of the fork/crotch is on more of an angle than the front, so naturally to keep the measurements equal, when drafting, it will drop down just below the horizontal crotch line at block development. Thinking it has to be on the same horizontal crotch line as the front is incorrect. You can see that in the Bray draft above.

As the angle of the back inseam increases, not only does the thigh size increase, but the bias of the fabric comes more into play. Bias will stretch out (more in certain fabrics) so sometimes the back inseam is shortened to account for bias stretch.

Lastly, in some trousers drafts, the back inseam is shortened to clean up the amount of fabric under the seat. Stretching the back inseam up with the iron before sewing it to the front, leaves the section under the body (before the seam turns vertically) lower.  Makes for a better fit in tailored trousers.

Calves                                  

An example of uneven seam lengths can be seen in some drafts which provide a bit of shaping for the  calves. You may see drafts/patterns where the back inseam and outseam from the knee to the hem are drawn with a slight convex curve. This increases the seam length relative to the corresponding seams on the trouser fronts. The extra length is eased in and provides a bit of shaping for the calves, and it increases the width over the calves as well.  This can be useful with very narrow trousers, or for people with prominent calves.

Knee shaping

You might also see some close fitting or speciality trousers drafted with a dart in the inseam and outseam at the knees to create a pocket at the knee. This is most often a style consideration.

next post - looking at the waistline .....

Looking at a trouser pattern shape problem

So, Hello! I am back after a very lengthy hiatus - its funny how we lose interest or motivation over time for some of the things we do. Other platforms pop up and it satisfies something different or us, and for me I think I needed a break and IG seemed useful, but it has issues too and I guess I found that my thoughts are less "Insta" so to speak.

but anyway......recently on Instagram....and her accompanying blog-

Handmade PHD was recently trying to dissect a pattern for trousers that were not working for her and I have a few thoughts as to whats going on there. She has been looking at various patterns and how they perform by virtually trying them on 3D avatars. 

So, instead of burdening her comment section,  I figure I could post some of my thoughts here instead.  

This is the digital pattern shape she is working with. She has drawn in grain lines from the centre point of the hem and knee on both pieces. That seems to be reasonable assumption on the front but not on the back as the perpendicular angle of the knee and crotch line don't make sense. 

I think there was a problem with the way the basic pattern has been developed, either at the block stage or during manipulations of the basic block.

Here is an example of a flat trouser draft from Metric Pattern Cutting for Menswear as an example - this would be the draft I would imagine would be used for this style of trouser. On the left they show a block developed with a straight side seam (which could be placed on the fold and cut as a one piece pattern) or, for a slightly better fit, a flat two piece trouser block.

Even in a flat block, the front and back of the pattern must directly relate to each other in the block development drafting stage.

From the basic block, one may then make modifications, like adding pleats to the front, without distorting the relationship between the front and back

Unfortunately the back pattern piece she has looks like it was from the straight side seam block and the front from the two piece. They just don't work together.

On the two piece block, you should be able to superimpose the front on top of the back, match the hem level, and centre the front piece over the back piece. The backs, which are drafted wider that the fronts at both the hem and knee, should have an equal amount showing beyond the fronts at the knee and the hem on both inseam and outseam. The centre leg/grain line should be right on top of each other.

Here is a little that exploration I did.

1. if side seams were straight, the centre front goes off grain and front hem at inseam drops 

2. the front is overlaid on the back, centered at the hem but the knee is not centred 

3. if the hems are on the same plane with the hip hip area touching, there is a big offset in the lower leg.

 

I also wonder why the back waist line has virtually no rise to it. You can see that the CB waist point is only marginally higher than the side seam at the waist. 

hmmmmmmm, I wonder if their back waist measure was too small, and to increase it,  they slashed and spread it? no, I tried that in a paper model and it didn't produce that kind of shape. 

I'm stumped there.....

But... I can imagine if the back waistline does not rise much above the horizontal construction line for the waist, then the centre back seam length must be made to intersect with the back inseam length somewhere out there in space. I can see how someone might make that make sense somehow.

I mean, there are patterns that don't have any rise in the back waist, which may look something something like this- of course that straight CF/CB line must be long enough to accommodate the full girth, so the crotch point will be quite a bit lower than a trouser with shaped CF/CB seam.   

 

There are some other issues that bear examining, like inseam length and side seam shape, but that will have to be discussed in the next post.

Do you have issues with the patterns you make up?