Final answer:
A hot iron can cause scorch marks on pants made of rayon or polyester due to the lower heat resistance of these synthetic fibers.
Step-by-step explanation:
A hot iron will cause scorch marks on pants with rayon or polyester in the fabrication.
When a hot iron comes into contact with rayon or polyester fabric, the heat can cause the fabric to scorch or burn, leaving behind visible marks.
This happens because rayon and polyester have lower heat resistance compared to natural fibers like cotton or wool. The heat from the iron can be too intense for these synthetic fibers, causing them to melt, discolor, or develop scorch marks.
To prevent scorching, it's important to adjust the iron's temperature according to the fabric's recommended setting and use a pressing cloth or a protective sheet between the iron and the fabric.