tape measures

Tape measure blades come in two types of finishes: satin or gloss. They have a concave design, from a semi-inward curve to a heavy one, as shown in the image to the right. This inward curve helps to strengthen the blade so it remains stiff when extended to long vertical or horizontal lengths without support. Once the blade is extended beyond its designed strength, it will either twist and/or bend, depending on the position of the blade (vertical vs. horizontal).
Holding the tape blade in a vertical position, you should be able to walk (push) a 1-inch blade up a wall about 12 feet before the blade twists and bends; a 3/4-inch blade can be walked about 9 feet.
In a horizontal position, a 1-inch blade pulled out at an upward angle of 15 degrees should extend about 7 to 8 feet before it bends; a 3/4-inch blade will extend about 5 feet before it bends.
These measurements apply to a blade with a quality design. A thin blade will twist and/or bend at least 1 foot or more sooner than the measurements given above.