How To Grade Seam Allowances

https://www.youtube.com/watch?v=H1rjdr3Bu10

Learn How To Grade Your Seam Allowances For Dressmaking

Once you have sewn a seam in dressmaking, or in most other sewing projects for that matter, your pattern instructions may ask you to grade the seam allowances.  This means to trim each layer to a different level so they are tiered.

The purpose of grading seam allowances is to reduce any bulkiness in that area and to help prevent the seam raw edges from leaving an imprint or ridge on the right side of the garment or sewing project.

Seam grading is usually done in areas where the seam will be enclosed like with collars or cuffs on a shirt for example.  It’s not normally necessary in areas where the seam allowances will be pressed open, like on a side seam.  Its also helpful when using thick fabrics.

To grade your seam allowances, sew your seam as normal. 

Then press it to one side according to your pattern instructions. 

Take your scissors, and trim each of the seam allowances down to different levels.  The layer closest to the outside of the garment should remain the longest.  Firstly I usually trim both layers by approximately half and then I separate out the two layers and trim just the one on top by half again. 

If you have more than two layers, you can graduate each of them down sequentially.

Duck-billed scissors are really useful for this task!