Repeating key words exactly

In technical and scientific writing, it is often necessary to repeat technical terms and to not use synonyms that might have slightly different meanings. It is important to choose exact terms and use them consistently.

Here is a simple explanation of why aerosol cans have curved bottoms. You’ll notice the author repeats key words, such as can, bottom, and product (highlighted in color), and does not vary the terms until the end, where he substitutes liquid for product. Such consistency of terms helps readers follow technical information.

The shape strengthens the structure of the Start of green highlighting. can End of green highlighting.. If the Start of green highlighting. can End of green highlighting. had a flat Start of green highlighting. bottom End of green highlighting., the force of the pressurized gas might push the metal outward. A curved Start of green highlighting. bottom End of green highlighting. has greater structural integrity, just like an architectural arch or dome. With this shape, most of the force applied at the top of the curved metal is distributed to the sturdy edges of the Start of green highlighting. can End of green highlighting..

The shape makes it easier to use up all the Start of green highlighting. product End of green highlighting.. Draining a flat-bottom Start of green highlighting. can End of green highlighting. would be like sucking up the last little bit of a glass of water through a straw: You would have to tilt the Start of green highlighting. can End of green highlighting. to one side so the Start of green highlighting. product End of green highlighting. would collect under the plastic tube. With a curved Start of green highlighting. bottom End of green highlighting. design, the last bit of Start of green highlighting. product End of green highlighting. collects in the small area around the edges of the Start of green highlighting. can End of green highlighting.. This makes it easier to empty almost all of the Start of green highlighting. liquid End of green highlighting..

—Tom Harris, “How Aerosol Cans Work”