Cutting and spreading pattern pieces are done to increase width or add fullness to the garment, as in the following examples:
- Increasing width and/or length on a pattern piece by cutting the pattern and moving the pieces apart. This is for making changes to commercial patterns, and is the opposite of Cutting & Lapping (see Image 1 below); or
- Cutting and spreading a pattern piece to add fullness for design purposes (see Images 2a - 2c); or
- Moving a dart (Images 3a-3d)
1. Adding length in a Pattern Piece
This is an alteration done on the Bodice Front to add length between the bust and the waist. The pattern piece is cut from the CF to the side seam, and the bottom piece is moved down the required amount.
When making alterations like this to commercial patterns, you need to keep in mind the effect that the change will have on the adjoining pattern pieces. In this case, you would need to make a similar change to the Back Bodice Block. If you don't you won't have enough length in the Back, and the side seams lengths will not match.
If you are using a cardboard block, you can trace out the new outline. If you are using a paper pattern, you place paper between the pieces and tape it together. In both cases you will need blend the side seam and the dart legs.
Click on any image to enlarge.
2. Cutting and spreading for added fullness.
We are going to look at cutting and spreading for fullness with this design to the left.
This flat shows gathers along one side of the dart, which require fullness to be added.
The design lines are drawn where the fullness is to be added.
Cut out the dart, then cut along the red lines; don't cut through the side seam.
Spread the required amount. In this case the amount it has been spread is fairly minimal; how much it will be spread will depend on the interpretation of the design. (Note: Seam allowance still needs to be added).
2. Cutting and spreading to move a dart.
This is original block with two darts; one in the side seam, one in the waist. The green line is the new design line; the side seam dart will be moved to the shoulder by cutting and spreading, creating a new block with a waist dart and a shoulder dart.
The original block is cut along the green line and the red line. I have pulled the two pieces apart here so it can be seen clearly.
After putting the pieces back together, hold them together at the Dart Point and then pivot the armhole piece so that A and B meet (i.e. close the side seam dart).
This is the final new block with a shoulder dart instead of a side seam dart.