logo      1. How aerosols work
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Basic operation P.2
What is an aerosol?
The definition of an aerosol is:

‘A collection of tiny solid particles or liquid droplets that are finely dispersed in a gas’.

So really, the aerosol is what comes out of the can rather than the can itself. However, when we talk about consumer ‘aerosols’, we mean a product in a pressurised container. So the word 'aerosol' has come to have two meanings: the everyday meaning and the technical meaning.

The parts of an aerosol
The basic components of an aerosol are:
  • a container with . . .
  • a product that is put under pressure by . . .
  • a propellant and pushed out through . . .
  • a controlling valve.

However, each of these features can vary enormously. On this page, we'll take a closer look at cans and go on to the contents on the next page.

Aerosol cans
There are two main ways of making the can:
  • Three-piece cans (sometimes two piece also)
  • One-piece cans
Photo of sheet of cans
Picture 1.1. Welded tinplate cans start as a flat sheet. They are then formed and welded.

A two or three-piece can is made from a flat sheet of tinplated steel. This is rolled into a cylinder and welded along the join. A cone is crimped onto the top ready to take the valve assembly and a dome is crimped onto the bottom.

The original flat sheet of tinplated steel can be coated with a protective lacquer on the inside. This stops the product interacting with the metal of the can. The advantages of this type of can are:

  • more compatible with corrosive alkaline products
  • magnetic – so easy handling on filling line
  • less expensive than aluminium
  • easier to produce larger sized cans.
Photo of extruded aluminium aerosol can
Picture 1.2. The extruded aluminium can on the left started as a slug of aluminium (on the right). It was pressed out using a die.

A one-piece can is made from a single slug of aluminium. This is extruded into a cylinder by punching it into a die. The top is shaped so that the valve can be mounted onto it later. The advantages of aluminium one-piece cans are:

  • lighter
  • compatible with corrosive acidic products
  • possible to produce smaller cans.
Question 1
All cans are tested once they have been filled. Some cans fail the test. Where do you think 3-piece cans are most likely to spring a leak?

Click shift/return to get a line break in your answer

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Summary                                           Close
  • an aerosol can contains a product and popellant
  • there are two main types of can:
  • one piece made of aluminium
  • three piece made from tinplated steel