How to enlarge a pattern in a non-existent size
There is nothing more frustrating than finding out that a pattern is not available in its own size. We will see here that there are solutions to enlarge the pattern in a reasonable way. Be careful, the gradation is normally done according to a very detailed table of measurements, with enlargement values specific to each type of garment but also morphology. This technique can be used to enlarge a pattern by one or two sizes, but beyond that, there is a risk that the pattern will no longer conform to the statures. This is the case when you want to transform a pattern into a very large size.
Principle of grading
Grading is the job of a grader or pattern maker.
A garment pattern is built in a well-defined size, such as 36 or 38. It is on this basis that the gradation will then be made. It is then necessary to refer to European standards and very detailed measurement tables to calculate the necessary enlargements between 2 sizes. The measurements to be reported take into account both vertical and horizontal values.
Examples of cases
A pattern is proposed from 36 to 46 while the desired size corresponds to a 34 or 48. A gradation is possible on all the pieces of the pattern.
A pattern is proposed from 34 to 48 whereas the desired size corresponds to 54.
A gradation is not recommended because the difference with the last proposed size is too important.
Use a graduated ruler to extend the lines, a square to draw perpendicular lines, a parrot (modeler's ruler with a curved shape) to draw curves.
Check that all the pieces of the pattern have been selected.
The aim of the exercise is to connect the different sizes of the pattern with a straight line at specific points on the layout. You must therefore apply this rule to each intersection between two lines forming an angle, but also at each assembly mark.
Once the lines are drawn, check that they extend beyond the first and last size.
Measure the distance between two points of intersection. This gap should normally be regular and repeated between each size.
If the purpose is to enlarge the pattern by one size, transfer this measurement beyond the last size to the outside of the room.
If the goal is to reduce the pattern by one size, transfer this measurement just before the first size, inside the piece.
Once all the transfers have been made, connect the new points together using the same layout as for the other sizes. That is to say that you must respect the straight lines and curves in order to preserve the cut of the model.
When all the parts have been graded, check that all the lines fit together perfectly. If a mismatch is found, it is quite possible that there is an error in the grading.
Thanks to your questionnaire, I went to see "how to enlarge a pattern in a non-existent size" and I will be able to sew the blouse and the Zenith dress in size 48 because I will benefit from your free pdf. I didn't buy the pattern at the haberdashery in Montlouis (37) because on the pocket, I saw that it wasn't in size 48. I'm going to get started thanks to your help. Many thanks!!!
Thank you for your valuable advice.
It is true that some sewing pattern are too tight in the waist and hips for me.
I will apply your precious advice to a pattern I bought from you.