How to check the accuracy of graded patterns pt.2
Picking up where we left off in part one, someone I’ll call Mary asks:
At this point I’m not 100% sure what the procedure is, hopefully you can confirm. Once I get the nest I will test it by sewing one sample? or should I sew every size?
The short answer is no, kind of. The real answer is that it depends. I’ll explain still another way to check the grade on the nest without convoluted charts. In part three I’ll explain why you mostly shouldn’t sew up a set of sizes to check the grade.
Checking the nest:
This presumes you provided the grade or grading guidelines and calculated its division across however many pieces. It also presumes you know where the cardinal points lie (these points are numbered in the Excel grade rule report I showed you in the first entry). What you want to do is measure along the XY grid to see the grade of each point and for each size. I’ll show you how to do this for one point; this is the junction of the side seam and under arm.
This first illustration below shows a line drawn perfectly vertical and another horizontal to intersect with the base size cardinal point. Since all of your sizes grow and shrink from the base size, each cardinal point of the base size is effectively the zero point.
In the illustration below, I’ve marked X-Y (perfectly horizontal and vertical lines) coordinates to intersect with the next larger size at the cardinal point. You need to measure the difference between the “medium” or base size and the next larger size along these coordinates -not at an angle.
By way of example, if this distance measures 1/4″ along the vertical (in this orientation) and you have four pieces, your grade should be 2″ -usually. You will have to confirm that the other pieces are also 1/4″ each.
You will also need to measure along the horizontal -this tells you the length grade at this particular point. All points are cumulative; you’ll need to add all of the length measures at each point to discern the total length grade.
A word of caution at this point if you think your style shouldn’t grow in length from size to size (because it usually should). Grading for sizes whether by girth or length does not refer to the dimensions that one static body would change as it gained and lost weight. Rather it is the average or median of still other bodies that happen to be larger or smaller. Many new companies (and consumers) don’t realize that gaining or losing weight does not mean one can substitute a larger or smaller size of a given brand or style that one usually buys. The latter would be fortunate but not guaranteed. It is possible that weight changes (particularly drastic ones) would mean one needs to buy another brand. Really (and).
But I digress. Below is an illustration of two sizes larger than the base or median size. Rinse, lather and repeat for each size.
Below I’ve illustrated how you want to measure the distances at each cardinal point.
One last thing to realize is that the increments per piece may not be uniform and if they are not does not mean the grader made an error. If your 4 halves going around the body’s girth are not more or less equal, some pieces will grade differently. For example, if you have one large main section at center front and or center back, coupled with a relatively tiny side panel, each piece may not grade 1/4″ for a 2″ grade because grades are proportionate. In this case, the larger front or back sections may grade 3/8″ and the comparatively small side panels may only grade 1/8″. It really depends. Grades can be as unique as styles and human bodies are.
~An aside- I’m aware that a lot of people will go through this and come to the conclusion that grading is really hard or complex. To that I have two responses. No it isn’t but it does presume given understanding that is specific to the job. Way back when, I didn’t used to explain in such detail and preferred to say “it’s complicated, leave it to the pros”. Then I discovered that people didn’t believe me. They figured because they are smart (and they are) and sewing is easy (everybody “knows” fashion people are kind of stupid and besides, mom did right on the kitchen table), they could figure it out themselves -to their later peril. I discovered that if I did explain the complexity, people could see that it was more advanced or complex than they thought so it was better to leave it up to professionals. Of course there are exceptions, people with a bit of experience who only needed a little nudge but most don’t fall in that camp. My point being, my practice of saying “it’s complicated, leave it to the pros” without explanation led to worse results.
My second point is that grading is quite logical and fairly easy to analyze once you get over the learning curve of knowing how to do it and knowing what is meaningful error. I definitely agree it is to your advantage to wade through some of this because you need to know how to check someone’s work. Particularly these days when many people don’t have all the financial resources they ideally need and so are relying on students, interns or people who have some training but never had the opportunity to gain meaningful experience or tutelage. [Even then, some advice (heavily context dependent) given by purportedly experienced graders can be distressing.] Once you get a handle of grading logic and practice, it will make a lot more sense and you can save quite a bit of money. You can also use this to train new hires who don’t have the benefit of experience.
In part three I’ll explain why sewing a sample of each size to test the grade is usually unnecessary and amounts to unwarranted expense of time and resources -and may not provide the results one anticipates.