Cooked foods and leftovers should always be kept in airtight containers and refrigerated. Any type of food, whether raw or cooked, should never be left for more than four hours at room temperature. Food poisoning becomes a risk when food is left out, especially in hotter temperatures.
Single yarns of the spun type, composed of many short fibres, require twist to hold them together and may be made with either S-twist or Z-twist. Single yarns are used to make the greatest variety of fabrics.
These fibers are blended together to give a particular look. (For example, black and white may be blended together to create a gray heathered yarn.) The term, heather, may also be used to describe the fabric made from heathered yarns.