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Alpha Testing: Measure, Walk, True

When a sewing pattern is released for sale, it has been  (hopefully) both Alpha and Beta tested: that means it has been tested by professionals and by amateurs.  You may have participated in Beta testing yourself, or read posts from testers. But do you know what goes into Alpha testing, before the Beta testing starts? A while back I wrote a post about Beta-testing of sewing patterns, and promised to write about Alpha-testing.  Here is the difference between the two:

Alpha testing is done during product development, either “in house”, or sent out to professional testing services. The purpose of Alpha testing  is to work out the kinks in a product before it goes into Beta-testing.  Alpha testers have a background in not only how to use the product, but also in how it is made, so that they can suggest fixes.  In apparel production, patterns are alpha-tested by the sample-hand and tech designer.

Beta testing is done after product development and alpha is complete.  It is performed by “average consumers”, who try the product and report back their findings in a non-technical manner.  The purpose of beta testing is to see if you and I can use the product  without problems. Beta testing does not require a background in knowing how the product was made, and the beta tester is not expected to suggest fixes, only to report problems.

Alpha-testing asks “Can I make this workable for the consumer?”

Beta -testing asks : “Does this work for me as a consumer?”

Alpha-testing  a sewing pattern has 3 purely technical steps:

  • Measuring each size to make sure the finished garment  matches the sizing guide or specifications, checking for correct proportions between sizes
  • Walking the  seams to test that  they match up when stitched together
  • Trueing the darts and seam corners to make sure that when stitched, the result is a smooth edge without peaks or jagged edges

…plus one step that can only be done by “eyeball” and experience in drafting and fitting:

  • Shapes: necklines, armscyes, sleevecaps

In the ready-to-wear garment industry, alpha-testing is a team effort,  not generally involving the fashion designer (because the designer and the pattern engineer have very different skill sets). When the samplehand cuts out samples, she notes any problems with the pattern and communicates them back to the pattern engineer, so that corrections can be made before the first fitting muslin is made. The samplehand generally has factory-line experience and can spot issues that will slow down the production line (such as trueing issues, or seams that don’t match). When the first fitting muslin is checked on the fit model, the tech designer communicates shape and fit corrections back to the pattern engineer, who makes adjustments for the next sample. The process continues until the fit sample is approved, and the corresponding pattern goes out for grading. After the pattern is graded, it gets checked again before being sent to the factory.

In the patternmaking industry, there may be more of an overlap between the responsibilities of the fashion designer and the pattern engineer, and in small independent businesses it’s possible that the owner fills both jobs simultaneously. Depending upon the resources and budget, testing may possibly get short-changed.

You’ve probably heard that its a good idea to sew a fitting muslin before cutting into your apparel fabric; I’d go a step further and say it’s a good idea to check the pattern and make any corrections necessary before even cutting your muslin. I’ll show you how to Alpha test a  pattern yourself. The pattern I’m checking is “Matilda” by Violette Fields Threads, a raglan peasant dress with a completely mirrored front/back: same bodice, skirt, neckline, armscye, sleeve.  There are only 2 pattern pieces: bodice and sleeve.  You can’t get any simpler than that.


Measuring and proportion:

  • Bodice Width: there is no body measurement chart given, so I’m using a standard waist measure from a basic industry chart, to check the pattern fit.  The pattern gives a Finished Measurement Chart, however it gives only the “waist with elastic”, which doesn’t tell you if the size will fit, since you don’t know how far the elastic stretches. So, I measured the pattern to to get the “waist extended” measurements, and from there I  calculated how much ease is allowed:


The ease is out of proportion: there is excess ease in the small sizes and not enough in the large sizes.  I put in a more logical ease (proportionate to the sizes), recalculate the waist measurements, and redrafted the  side-seams:


  • Skirt sweep:  to measure the sweep just double the skirt pattern minus seam allowance:

sweep pattern

The ratio between sizes looks way off: in the largest sizes, the skirt has a 2.4 ratio to the bodice….for the smallest size the ratio is 3.61.  That creates different dress silhouettes between the sizes, and also different effects for the gathered fabric. The general idea is that the lighter/sheerer the fabric, the higher the gathering ratio:

  • heavier-weight fabric: 1.5 to 1
  • medium-weight fabric: 2 to 1
  • light-weight fabric: 3 to 1
  • sheer lightweight: 4 to 1

So if you are using the same fabric for a size 2 and a size 10, the gathering effect would be quite different using this pattern. I test my most-used fabric, Kona cotton broadcloth, to see if it will gather up to a 3.5 ratio, by gathering a 35″ strip with the highest tension:


I can barely get it tight enough to fit 10″:


Since I’m not planning to use lightweight/sheer fabric, I standardize the skirt sweep ratio to a basic 2.5 across the size scale.  This means the pattern needs to be reduced in the smaller sizes, but this is important if you are making multiple sizes that hang on a rack together, or are sold to sisters, flowergirls, etc.


Walking: this is the process is measuring each adjoining seam to make sure they are of the same length, or will be after any necessary easing-in or gathering is done. When measuring curves, this job is made easier with the use of a flexible ruler:


There is no need to walk this particular simple pattern because the only 2 different pattern pieces  that get joined together are the  bodice armscye to raglan sleeve….and in this style they are  drafted identically , as you can see by using a lightbox:



Trueing: there are no darts to close in this pattern; the only areas to be checked for trueing are the tops and bottoms of adjoining seams.  You want them to be as close to 90-degrees as possible, so that after stitching the seams together, the resulting edge will be a smooth line (180 degrees).

NOTE: some patterns have a seamline at an angle, for example at the seam allowance one pattern piece will have an 80-degree angle and the adjoining pattern piece 100-degrees…but they will always add up to 180-degrees,  a straight line.  Common places for angled seams are:

  • shoulder seams of scoop necklines
  • tailored jacket sleeves where the seam is not at the underarm but rather at the middle of the back armscye
  • angled bust darts
  • bodice princess seams


This is the pattern shape of the  bodice and the sleeve at the neckline:



The corner starts out okay in the smallest size, however as the sizes increase, the angle decreases. When the sleeve and bodice are stitched together, a peak forms (this is a size 6):


This peak angle will  make it difficult to fold the fabric over to create an elastic casing.  To true the pattern corners (sleeve and bodice) , draft 90-degree right angles, then when the raglan seam is stitched, the neckline will have  a smooth line, easy to press down for the elastic casing:


Shapes: the only shaping involved in this style is the neckline and the armscye.  The neckline is the same line for all sizes, just extended at the sleeve-join.  But the armscye shape changes dramatically as the sizes are graded: it starts as a French curve in the smallest sizes, and turns into square-ed off ovals in the larger sizes:


To make sure the shape is the same, just graded for size, use a French curve and draft revised shape-lines for the armcyes:


The same correction needs to be applied to the sleeve, so that they match when stitching together. And that’s it!

Given the expense of alpha testing, it’s possible that patterns from smaller businesses may not be thoroughly tested. If you are not sure, it is worth the investment of a few minutes of your time to Measure, Walk, True….before cutting out your muslin.

PS: finished garment (my customer wanted no elastic in the waistband, and a flounce added at the hem):



10/25/2016 UPDATE: The Matida pattern has been updated!  The raglan armscye has been trued at the neckline (original at left, revised at right):


…..and has been French-curved at the underarm (again, original on the left, revised on the right):


If you have already purchased this pattern you will receive an email with a link to down load the revision. The revised pattern does not include size 12 months, presumably because a new pattern is being released today with infant sizes.


  • Kate

    Thanks for all of the important information. I love knowing what to look at before deciding to sew a pattern. Maybe some day I’ll be able to correct drafting issues and actually sew patterns with problems.

  • JustGail

    Part of me wonders if the excess ease in the smaller sizes was intended to allow for diapers. But then again, modern disposables aren’t bulky around the waist. How much waistline bulk is there with cloth diapers and covers?

    Another highly informative post, thank you!

  • Angela

    Excess ease in baby size patterns has been driving me nuts lately! I can’t seem to find patterns anywhere that stitch up to comparable RTW sizes, especially for young babies.

  • [email protected]

    It’s possible…but this is an empire-waist style so it doesn’t need to fit over diapers. That said, I do appreciate patterns that are drafted separately for diaper-wearing infants, and potty-trained toddlers!

  • Sarah Turnbull

    What a helpful post. I am going to print it out and consult it avery time I start working on a new pattern. Just recently I was caught out by an untrued dart on a 1970s McCall’s pattern (I thought they did things properly in the olden days grumble grumble).

    I might make a checklist so I can tick off each item.

  • [email protected]

    Coincidence but I just tried a McCall’s wrap dress, a vintage pattern that I bought online mostly for the purpose of seeing how they constructed the sash to go under/through the opposite bodice side-seam for tying…and the instructions said NOTHING about how to put the dress on and tie it! Nobody’s infallible. (I had to split open the side-seam about 2″ to pull the sash through). So anyway you’d think that “measure/walk/true” would be basic, yet sometimes it gets overlooked!

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