How to: convert sewing patterns for latex

Firstly, I’ve only picked up a rough understanding of sewing patterns by osmosis, I don’t actually sew.

Sewing patterns differ from the patterns you need for latex as follows:

  • they are printed with a seam allowance, sometimes the stitching line is also printed, sometimes it is not.   If the seam allowance were 3mm then that would give us a 6mm overlap which would be great.  However, the seam allowance is normally 1/2 inch, this means the pattern pieces start off much too large.
  • they are generally printed on tracing paper – not ideal to draw around, and pinning it to the latex is not an option.
  • the sizes look like women’s retail sizes 10,12,14 etc., but they don’t equate to modern retail sizes.  The pattern normally has sizing information on the pack. This applies especially to vintage patterns.
  • patterns are sized with an ‘ease’.  This is because normal fabrics are assumed to have zero stretch, and therefore a garment would restrict the wearers movement too much if it were fitted exactly to the body.  The ‘ease’ is the amount by which the garment is made bigger than the body to allow movement.   For latex patterns we generally want negative-ease, i.e. we’ll make the garment 5-10% smaller than body measurement.
  • body shape is often achieved using darts.  Darts should be avoided with latex patterns as they look like a bodge; they need to be converted into separate pieces.
  • patterns pieces are cut with an understanding of the direction of grain/pattern.  We don’t have to worry about that aspect (unless you’re using patterned latex).
  • pattern pieces are often cut on-the-fold, we won’t actually be folding the latex but instead flipping the pattern piece over.

Another consideration is that not all garments translate well to latex.

My approach to using sewing patterns is:

  • digitise the pattern
  • translate darts to seams
  • adjust size as required (taking seam overlaps into account)
  • arrange pieces for printing.

Digitise the pattern

Photograph the pattern on the cutting board:
  • Iron (heat 1, no steam) pattern pieces if required so that they will lie flat.
  • Set up the camera to be pointing straight down and square to the cutting board.  Use a tripod so that the alignment is identical for every photo.
  • Mark a frame on the cutting board (e.g. using masking tape) with a known size (unless you can get the whole cutting board in).
  • Photograph each piece.
  • Adjust one photograph to remove lens distortions, and crop to match identically to centimetre markings on the cutting board.
  • Apply the same settings to all photos.
  • Create a new iDraw (now Autodesk Graphic) file and load the first photo as a background image and set up a 1cm grid that matches exactly with the markings on the cutting board.   The photo is now represented exactly 1:1 in the drawing package.
  • Trace a line on the pattern, have iDraw display the measurement of this line and check this against the actual pattern piece.  If you do not get a perfect measurement then review the above steps.
  • Save each pattern piece picture as a background in a separate iDraw file.
  • Trace around the pattern pieces, capturing all markings.
  • Group all the markings for a piece.
  • Copy all the groups into a new iDraw file that does not have a background image.  This file will be much smaller (Kb rather than Mb).

Translate darts to seams

 to be completed

Adjust sizes (and seam allowances)

There are three aspects to consider:

  1. The pattern will have seam allowances, e.g. 1/2 inch, and we need 2-3mm.
  2. The pattern (assuming that it is not intended for lycra or jersey)  will allow for ‘ease’. This can be reduced, and for form-fitting items needs to be converted to a ‘negative ease’.
  3. Adjusting to your size.

to be completed

Arrange parts for printing

to be completed


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