The Collapsible Tube: A Container That Is Always Full

Rand's invention relates to "a mode of preserving paints and other fluids by confining them in close metallic vessels so constructed as to collapse with slight pressure, and thus force out the paint or fluid confined therein through proper openings", which can then be closed air-tight. The vessels are "at all times full, whatever be the quantity of fluid matter remaining therein". He names "grain-tin, lead, and pewter" as the best and cheapest metals, of such thickness "as readily to yield to pressure and to be caused to be permanently collapsed". Fig. 1's vessel is "made of grain-tin drawn into a tube", the metal "about one seventy-fifth of an inch in thickness", its ends closed by melting the pressed edges or by soldering; a pair of forceps b holds the end for closing it with a blowpipe or hot iron. A hole is made at c and "it is better that the pressure should be made at the end, d, of the vessel", so the collapsed end "may be rolled up". Fig. 4 adds a short tube with "a screw-cap". He warns that the fluid must not be one "chemically prejudicially acted on by the metal employed".

Mix a little oil paint from the set with a few drops of linseed oil. Fill two empty paint tubes from the open end with a palette knife, fold the end over twice with flat-nose pliers and crimp it flat. Put the same paint in a small open-topped jar with a loose lid. Each day for a week, squeeze a pea of paint from a tube and rolling up the end, and take a pea from the jar. Note when the jar's paint grows a skin and when the tube's does. Measure the flattened length per squeeze with the caliper and compare with the notebook's millimetres per millilitre.

**US 2,252**, dated 11 September 1841, was granted to **John Rand**, a citizen of the United States then living in Middlesex, England; he is the portrait painter John Goffe Rand. It claims the mode of preserving paint in vessels that collapse by slight pressure as their contents are removed. **Honest limits.** Tin's modulus and yield stress in the notebook are typical values; lead and pewter behave similarly. Lead tubes are not used for food or cosmetics today.