Modified seam allowances are used in high-end designing departments and throughout the industry.
Marking patterns with varying seam allowances ensures faster, more accurate sewing, saves fabric, time, and effort, giving more professional results. Cathy, Contemporary Fashion Education student demonstrates by modeling a blouse she made using these procedures. Cutting and sewing on the traditional 5/8 inch seam allowance, then trimming the seams after sewing means cutting the garment twice.
In the diagrams below are some suggested seam allowances:
If one traces the patterns as the seams are modified then the original printed pattern is left intact and can be easily referenced. Tracing paper, available at any art supply store, works really well. I buy the 50 yard 36 inch wide yellow canary. White is too opaque.
For a 3/8 inch seam allowance, remove 1/4 inch.
For a 1/2 inch seam allowance, remove 1/8 inch.
Curved seams that have stress, such as princess seams MUST have a seam allowance of 3/8 inch. Curved seams that do NOT have stress such as collars are usually given a seam allowance of 1/4 inch, but if the fabric frays easily use a 3/8 inch seam allowance.
Waistbands are usually given a 3/8 inch seam allowance on the waistband at the waist A waistband must always have at least a 3/8 inch seam allowance at the waist as a 1/4 inch seam allowance is not strong enough to support the skirt. Other seams in the waistband usually are given a 1/4 inch seam allowance, but may have a 3/8 inch seam allowance.
SEAM ALLOWANCES used in the industry
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