Sewing Tips 🧵 How to Attach Non-Fusible Sew-In Interfacing

Learn how to attach sew-in interfacing, a non-fusible type of interfacing used by sewers and tailors. Get step-by-step tutorials and tips here 🤓

Sew-In Interfacing for Beginners: A Tutorial

Interfacing is an essential tool for giving structure and shape to sewing projects. One interfacing technique is sew-in interfacing, where the interfacing is stitched directly into the garment’s seam allowances. This method can provide soft support without the stiffness and potential puckering of fusible interfacing. Here’s a beginner’s guide to working with sew-in interfacing.

What is Sew-In Interfacing?

Sew-in interfacing is a layer of fabric that gets sewn into the seam allowances of a garment to provide light to medium stabilization. It’s useful for adding body and shape to collars, cuffs, waistbands, lapels, and other areas without the bulk and wrinkling risks of fusible interfacing.

Sew-in interfacing is cut from a separate piece of fabric and then stitched into the garment’s construction seams. This permanently attaches the interfacing to the main fashion fabric. The end result is subtle structure, support or thermal insulation. It’s an excellent choice for delicate fabrics like silks and soft wovens that could react poorly to fusible adhesive.

How to Prepare and Cut Sew-In Interfacing

The first step is to identify which pattern pieces need interfacing on your project. Trace these pattern pieces onto the interfacing fabric, carefully matching the grainline. Be sure to purchase an interfacing variety that suits your fabric weight and drape.

Lightweight sew-in interfacings are good for delicates like silks and laces. Medium-weight versions can support stable wovens like cottons and linens. Go heavier for rigid fabrics like canvas. Always pre-wash the interfacing to avoid shrinkage issues.

Cut the interfacing pieces slightly smaller than the pattern pieces to reduce bulk in the seams. A 1/8″ to 1/4″ seam allowance reduction is usually sufficient. Mark any gathering lines or dots from the pattern onto the interfacing as well.

Sewing In Interfacing: Step-By-Step

  1. Pin the interfacing pieces to the wrong side of the corresponding fabric pieces, matching the raw edges together. Use sewing clips for easier handling.
  2. Apply basting stitches or fabric glue along the edges to hold the layers together temporarily. This keeps them from shifting while sewing the garment construction.
  3. When sewing the garment seams, the interfacing will automatically be stitched into the seam allowances, attaching it permanently to the fashion fabric.
  4. Sew the seams with the standard 5⁄8″ seam allowance, being careful not to stretch or skew the interfacing. Go slowly and adjust the presser foot pressure if needed.
  5. Press all seams flat, pressing the allowance toward the garment side. Use a press cloth to avoid impression marks. Steam pressing will help shape curved areas like collars.
  6. Grade or notch bulky seam allowances carefully to reduce thickness. Clip curved edges where necessary as well.

Once the main construction is complete, the interfacing should be firmly anchored into the garment. The result is light to medium support and structure without fusible adhesives or stiffness.

Sew-In Interfacing Tips

  • Softer, lighter interfacing is ideal for delicate fabrics and will have more drape and flexibility than fusible versions.
  • Cut interfacing pieces 1/8″ to 1/4″ smaller than pattern pieces to reduce bulk in seams.
  • Always stitch interfacing into garment seams using the standard 5⁄8″ seam allowance.
  • Go slowly when sewing through multiple layers to avoid shifting or stretching.
  • Press seams well, pressing allowances toward the garment side. Use steam and press cloths.
  • Carefully grade or notch allowances to reduce thickness at seam intersections.

What’s the Best Interfacing for Sew-In?

Woven sew-in interfacing has lengthwise and crosswise yarns for a soft drape and stability. Good for tailored garments.

Non-woven interfacing uses randomly aligned fibers for stretchability and flexibility. Ideal for knits and bias-cut pieces.

Pellon SF101 is a popular lightweight woven that’s suitable for most wovens. Provides structure without stiffness.

Weft insertion interfacing has horizontal yarns woven into a vertical fiber base for drape. Works well for softer tailoring and eveningwear.

Horsehair canvas is a heavyweight sew-in option for serious shaping in collars, chest pieces, and lapels. Requires meticulous pressing and steaming.

Always test interfacing samples on fabric scraps before cutting final pieces. Check that the weight and feel are suitable for the project’s fashion fabric and desired structure.

Top 5 Uses for Sew-In Interfacing

  1. Collars and lapels: Adds body and shape for crisp edges; avoids fusible stiffness.
  2. Waistbands and cuffs: Supports structure while allowing flexibility.
  3. Delicate fabrics: Provides subtle support for silks, laces, and soft wovens.
  4. Knit fabrics: Stabilizes stretchy knits and prevents sagging.
  5. Bias-cut pieces: Reduces stretching along the bias grain.

Sew-In Interfacing vs. Fusible Interfacing


  • Provides light to medium support
  • Maintains fabric drape and feel
  • Good for delicate and bias-cut fabrics
  • Won’t wrinkle or pucker
  • Takes more time to apply


  • Supports very structured areas
  • Bonds stiffly to fabric
  • Can cause rippling in delicate fabrics
  • Quicker application method
  • Permanently alters hand of fabric

Choose sew-in when you want light shaping without fusible stiffness. It’s ideal for softer fabrics and projects needing flexibility. For heavy tailoring or support in fray-prone fabrics, go with fusible interfacing instead.

Troubleshooting Sew-In Interfacing

Wrinkling: Press carefully with steam. Soften fused areas by dampening and pressing. Reduce seam bulk.

Stretching: Use lighter pressure and stabilizer when sewing. Interface knits on the cross-grain.

Poor adhesion: Ensure interfacing is caught in the seamline. Press tightly and use seam tape if needed.

Visible through fabric: Select a lighter interfacing and press well after sewing. Consider fusible.

Get the Most Out of Your Interfacings

With the right interfacing selection and careful application, sew-in interfacing can add shape and structure to garments without sacrificing comfort and drape. Always test samples first, and adjust sewing technique to prevent stretching, wrinkling, or shifting. With practice, you’ll be able to give garments a perfect amount of support for a flawless finish.

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