Mistakes & fixes

Extending sleeves that fall short requires a deeper hem let down, an added cuff, or a contrasting fabric extension at the wrist. Check there's enough hem allowance before promising extra length.

Adding room to a garment that's too tight relies on unpicking the existing seam and resewing with a narrower allowance, which only works if enough seam allowance remains. Check the seam before promising this alteration.

A knit edge that ripples into an unwanted wavy, frilled finish happens when fabric was stretched while being serged or hemmed. Ease the fabric through the machine without pulling and use a less dense stitch.

Visible loops sitting proud of the seam point to unbalanced tension, most often a bobbin thread with too little resistance. Rethread top and bobbin, adjust tension gradually, and test on scrap first.

Stitches that sit slack and don't lock into the fabric come from top tension set too low. Increase the top tension gradually and test until stitches lock in the middle of the fabric.