Sewing Instructions for AMC Performance Fabrics
Getting the best results from AMC performance textiles starts with proper sewing technique. Whether you're constructing boxed cushions, installing welt, or setting up a zipper closure, the right thread, needle, and seam type make the difference between a durable finished product and one that fails prematurely. Below, we've outlined our recommended thread and needle guidelines, common upholstery seam types, and a step-by-step sewing sequence to help your team get consistent, professional results with our fabrics.
Basic Upholstery Sewing Instructions
1. Choose the Correct Thread
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Bonded polyester is the industry standard for most upholstered furniture because it offers excellent UV resistance and strength.
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Bonded nylon is very strong but is better suited for indoor applications.
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Common thread sizes:
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Tex 70 – Light upholstery
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Tex 90 – Standard furniture upholstery
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Tex 135 – Heavy-duty commercial seating
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2. Use the Proper Needle
Needle size should match both the fabric and thread. For vinyl and coated fabrics, leather-point needles often produce cleaner stitches.
Thread Size | Needle Size |
|---|---|
Tex 135 | #22-24 |
Tex 90 | #20-22 |
Tex 70 | #18-20 |
3. Common Upholstery Seams
Plain Seam
The most basic seam. Used where the seam will not receive heavy stress.
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Place right sides together
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Sew a ½-inch seam allowance
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Open the seam
Topstitched Seam
Adds strength and a finished appearance. Very common on cushions.
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Sew the plain seam
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Fold seam allowances to one side
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Sew through all layers approximately 1/8–1/4 inch from the seam
French Seam
One of the most attractive seams for upholstered furniture.
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Sew the panels together
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Open the seam
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Fold allowances apart
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Sew two parallel rows of stitching
Frequently used on:
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Hospitality seating
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Marine upholstery
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High-end residential furniture
Welt (Piping)
Adds definition and protects edges. Use a welt foot for best results.
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Wrap fabric around welt cord
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Stitch close to the cord
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Sew the welt between two fabric panels
Boxing Cushions
A boxed cushion consists of:
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Top panel
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Bottom panel
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Boxing strip
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Welt (optional)
Steps:
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Sew welt to the top panel
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Sew boxing to the top
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Install zipper in the boxing
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Sew the bottom panel
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Turn right side out
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Insert foam
4. Installing a Zipper
For reversible cushions:
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Use upholstery zipper (typically #5 or #10 nylon coil)
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Install in the boxing rather than the cushion face
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Leave 1–2 inches unsewn at each end
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Always open the zipper before sewing the final seam so the cover can be turned right side out
5. Stitch Length
Typical upholstery stitch lengths:
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6–8 SPI for woven upholstery fabrics
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Decorative topstitching: 5–6 SPI
Avoid extremely short stitches in vinyl, as they can perforate the material.
6. Fabric Alignment
Always:
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Match fabric grain
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Match pattern repeats
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Center stripes or plaids
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Mark centers before sewing
Poor alignment is one of the first things customers notice.
7. Cutting Tips
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Use a rotary cutter whenever possible
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Cut with the fabric face down
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Label each panel
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Mark centers with small notches or chalk
8. Sewing Sequence
A common workflow is:
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Cut all panels
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Mark centers
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Sew welt
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Attach welt to top panel
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Sew boxing to top
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Install zipper
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Sew bottom panel
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Turn cover
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Steam lightly
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Insert foam
9. Machine Settings
A walking-foot industrial sewing machine is preferred because it feeds multiple layers evenly.
Typical settings:
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Thread tension balanced so stitches lock in the middle of the material
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Presser foot pressure just enough to prevent slipping
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Medium stitch speed for better control
10. Quality Checklist
Before completing the piece, check that:
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Seams are straight
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Stitch length is consistent
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No skipped stitches
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Welt is even around corners
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Pattern matches across seams
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Zipper operates smoothly
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Cushion corners are full and square
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No puckering or wrinkles