What type of stitch is commonly used for smart trouser alterations?

The use of a normal stitch is preferred for smart trouser alterations due to its versatility and ability to provide a clean, professional finish. A normal stitch, which involves a single line of thread, allows for precise adjustments to be made without compromising the fabric's integrity or altering the garment's structure too much. This stitch type adapts well to a variety of fabrics typically used in smart trousers, ensuring that the alterations blend seamlessly with the original garment.

Alternatives like flexible stitches, double stitches, or curved stitches may not be suitable for everyday alterations. Flexible stitches, for example, are often used in materials that require stretch but might not provide the necessary strength for tailored trousers. Double stitches can create a heavy seam that may not suit the elegant silhouette of smart trousers, potentially making the seams too prominent. Curved stitches serve specific purposes, especially in shaping garments, but do not provide the flat and discreet finish desired in smart trousers. Hence, the normal stitch stands out as the optimal choice for clean, refined adjustments.