Garment Construction and Sewing Techniques
What the exam tests
Machine and stitch knowledge, seam selection, seam finishes, and the correct construction sequence. Questions may ask which seam suits a fabric or what causes a sewing fault.
Core rules
- Stitch classes: 301 lockstitch is the standard straight stitch; 504 overlock neatens and stretches; 401 chainstitch is used where stretch is needed.
- Plain seam is the default; French seam encloses raw edges and suits sheer, lightweight fabrics; flat-fell seam is strong and neat for denim and shirt side seams; lapped seam is common in industrial knitwear.
- Seam finish depends on fabric: overlock for knits, bias binding for unlined jackets, pinked or zigzag for stable wovens.
- Correct needle size, thread tension and presser foot pressure prevent puckering, skipped stitches and needle breaks.
- Pressing is not ironing: pressing lifts and sets; ironing slides and can stretch.
Worked example
An unlined sheer georgette dress needs a strong, clean seam that will not fray. Reasoning: a plain seam would leave visible raw edges; an overlock is bulky and may show through sheer fabric. A narrow French seam encloses the raw edges inside two stitching lines and gives a clean finish, so it is the best choice, provided the seam is trimmed to about 3 mm before the second stitch.
Traps
- Using a plain seam on unlined sheer fabric and calling it “finished”.
- Choosing flat-fell for bulky fabric without adjusting the seam allowance.
- Diagnosing puckering as “bad thread” when tension or needle size is wrong.