Online Patternmaking Classes
by Don McCunn
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The Underbust Pattern

The Underbust Corset pattern is a good project for the first time corset maker. The fitting and construction processes are very straight forward. The instructions provided here are also required to create the torso portion of the Strapless and Shoulder-Strap Corsets. There are three basic steps to follow.

Body Wrap
Body Wrap
The Pattern
The Pattern
Muslin Mock-Up
Muslin Mock-Up

Materials and Tools

To create an Underbust Pattern, you will need the following materials and tools.

Materials Tools
  • Press'n Seal (1 roll)
  • Masking tape, 3/4" & 2"
  • Pattern paper
  • Muslin (1/2 yard)
  • Sewing thread
  • Rigilene boning (3 yards)
  • Eye or grommet tape (1 yard)
  • Shoe lace
  • Basic sewing tools
  • Marking pen (optional)
  • Pencil
  • Tape measure
  • Velcro (1 yard)
  • Paper scissors
  • Fabric scissors
  • C-Thru ruler
  • Hot Knife (optional)

Create a Body Wrap

Use the steps below to create a body wrap that shows the shape of the body. The first video for each step shows the process as a two-person operation. The second video shows it as a do-it-yourself, DIY, process.

  1. Apply Press'n Seal to the body.
  2. Reinforce the Press'n Seal with masking tape.
  3. Draw the desired design lines on the masking tape.

Applying Press'n Seal

Two Person Press'n Seal Mold

  1. Apply the Press'n Seal from side-to-side on the back, then smooth it out.
  2. Apply Press'n Seal to the front covering the torso is all around the body.

DIY Press'n Seal Mold

Reinforce Press'n Seal with Masking Tape

Use masking tape to reinforce the shape of the body wrap. In addition to stabilizing the shape, the masking tape provides a good surface for drawing the desired design lines.

Two Person Masking Tape

  1. Use masking tape to cover the back from the underarm area down to the waist, positioning the tape horizontally.
  2. To cover the hips, place the masking tape diagonally. This allows the soft tissue in this area to be compressed.
  3. Continue placing the masking tape from around the side of the body to the front.
  4. When you are taping the waist area, you can compress the waist by completely encircling the waist with the masking tape.

DIY Masking Tape

  1. For DIY applications, it is best to simply wrap the tape around the body, horizontally angling the tape slightly downward with each successive pass.
  2. After the tape is applied, smooth it out by hand.

Draw the Design Lines

Determining the seam lines is best done before you remove the body wrap. This way you can easily follow the changes in the contour of the body. When this is a two-person operation, draw in the full design lines. When you are doing it yourself, just make marks at key reference points, then complete the lines after you have removed the body wrap.

Two Person Design Lines

  1. Draw the Center Front line down the middle of the body.
  2. Draw the bottom of the corset to the Side Seam.
  3. Locate the Side Seam just beyond the side of the breast.
  4. Directly under the apex of the bust, draw the Side Front line.
  5. Draw the Center Back line directly over the spinal column of the body.
  6. Draw the Side Back line where the contour of the body starts to curve to theside.
  7. Draw the bottom of the corset around the back.
  8. Place a narrow strip of velcro around the body just under the breast and draw the top of the Underbust Corset.

DIY Design Lines

Create the Paper Patterns

Paper patterns will be a more stable record of the corset shapes than the Press'n Seal body wrap. After you have removed the body wrap, use the steps below to create the paper patterns. Once the patterns are created, keep the parts of the body wrap in case you need them for future reference.

  1. Reinforce the inside of the body wrap with masking tape.
  2. If you are creating patterns from a DIY body wrap, use the marks to draw incomplete design lines.
  3. Add labels and sewing notches to each shape, then cut the body wrap along theseam lines.
  4. Transfer the shapes from the body wrap onto pattern paper.

Reinforce the Mold

  1. Remove the body wrap.
  2. From the inside, add masking tape to reinforce the shape of the body wrap.
Inside of Reinforced Wrap
Inside of the Reinforced Wrap

Label and Cut the Body Wrap

Before you cut the body wrap, label the location of each piece and add sewing notches. The sewing notches are important because they are the most reliable fixed reference when you start to cut the body wrap apart. If you are working from a DIY body wrap, draw in complete design lines.

Design Lines for a DIY Mold

Adding Sewing Notches

  1. Label each shape of the body wrap to identify it's location. You can use abbreviations such as CF for the Center Front section, etc.
  2. Add sewing notches across each seam location and identify them with sequential numbers.
  3. Cut the body wrap along the seam lines.

Use the Body Wrap to Create Paper Patterns

Labeled Body Wrap Labeled Body Wrap
Cut Pattern Pieces Cut Pattern Pieces

The body wrap shapes can now be traced to create paper patterns. This includes verifying the length of the seam lines. The final step is to add seam allowances. If you use 3/4" (18 mm) seam allowances, the seam allowances can be used as channels for 1/2" (12 mm) boning in fitting a muslin mock-up.

  1. Lay out the body wrap pieces on pattern paper. Leave enough room betweenthe pieces for seam allowances.
  2. Trace the shapes of the body wrap pieces, including the sewing notches.
  3. Label the pattern pieces.
  4. Verify that the length of each adjacent seam allowance is the same. Use thesewing notches as the primary reference points, adjusting the lengths asnecessary to make both sides of the seams even.
  5. Add 1/2" (12 mm) seam allowances to the top of the corset.
  6. Add 3/4" (18 mm) seam allowances to all other seams.
  7. Cut out the pattern pieces.
The Pattern
Completed Paper Pattern

Create and Fit a Muslin Mock-Up

Before creating a wearable corset, check the pattern shapes for accuracy by creating a muslin mock-up. The mock-up can be created using simplified sewing and finishing techniques that would not be appropriate for a wearable version. It will allow you to verify the shapes and make design decisions. There are four basic steps to create and fit a mock-up. For this example, plastic Rigilene is used for the boning.

  1. Prepare the Rigilene boning.
  2. Cut and sew the body of the corset and the boning channels.
  3. Stitch the design lines in a contrasting thread color.
  4. Verify the fit of the muslin mock-up.

Prepare the Rigilene Boning

Rigilene boning is available in most fabric stores, so it is a good product to use for muslin mock-ups. While the boning can be cut with scissors, the instructions below show how to cut it with a hot knife, thus sealing the ends of the boning to prevent fraying.

  1. Use the corset pattern to mark the length for each piece of boning, including the center back.
  2. Use the hot knife to cut and seal the boning lengths.
 Black Rigilene & Hot Knife
Black Rigilene & Hot Knife

Sew the Body of the Corset and the Boning Channels

The 3/4" (18 mm) seam allowances can be used as channels for the boning.

  1. Fold under the center back seam allowance in preparation for adding the lacing.
  2. Cut the corset shapes out of muslin.
  3. Indicate the sewing notches on the muslin.
  4. Pin then sew the corset sections using a 3/4" (18 mm) seam allowance.
  5. Press the seam allowances for the side front, side, and side back seams of the corset toward the side, then sew along the edge of the seam allowance to create a channel for the 1/2" (12 mm) Rigilene boning.
  6. For the center front seam allowance, sew the seam allowances to each other along the edge to create a boning channel. Do not sew this seam allowance to the body of the garment.
Sewn Underbust Corset
Sewn Underbust Corset

Sew the Design Lines and Lacing Eye Tape

Use a contrasting thread to indicate the design lines of the corset. For this example, eye tape is used for the lacing at center back and the boning is inserted in the channels.

  1. Use contrasting thread to sew a reference line 1/2" (12 mm) down from the top edge of the corset. This line of stitching will seal the top of the boning channels except at center front which should be sewn closed separately.
  2. Use contrasting thread to sew reference lines 1-1/2" (38 mm) in from the center back edge on both sides of the muslin mock-up.
  3. Sew a length of eye tape along the center back reference lines created in Step 2.
  4. Press the fabric along the eye tape then sew a 3/4" (18 mm) boning channel at center back.
  5. Insert the Rigilene boning in the boning channels.
  6. Use contrasting thread to sew a reference line 5/8" (16 mm) down from the bottom edge of the corset. This line of stitching will seal the bottom of the boning channels except at center front which should be sewn closed separately.

The muslin mock-up is now ready for a trial fitting. For the trial fitting, a shoe lace can be used to lace the muslin mock up.

Completed Underbust Corset Muslin Mock Up
Completed Underbust Corset Muslin Mock Up

Fit the Muslin

The final step in creating the patterns is to fit the muslin mock-up. There may be little or no fitting required. During this process, you will be able to see how the fabric works on the body so that you can make refinements for any design you may wish to create.

  1. Lace the corset.
  2. Mark any fitting adjustments you want to make.
  3. Verify the type of closing devices you want use and mark their lengths on the muslin.
  4. Determine the location of any boning to be added in addition to the boning at the seams.
Front, Side, & Back of the Muslin Mock Up
Front, Side, & Back of the Muslin Mock Up

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