Traffic signs are our guides on the road. They give us a wide range of information to avoid potential dangers, to indicate routes or to help us comply with standards. They can have different shapes, colours, and symbols recognizable by the Highway Traffic Act that we all need to know before we get behind the wheel. Having been on the side of the road since the Middle Ages, they multiplied after the arrival of the automobile and have evolved well since then. Let’s see how traffic signs are manufactured today.
The graphic design of each sign is now done using software. Each model must follow strict graphic guidelines, registered with the Ministère des Transports du Québec. In particular, the government requires a specific degree of reflectivity, which means that the panels must always be designed using a special film. For the graphics of the sign, it is a computer program that guides the cutting machine. The cut-out pattern will then be carefully detached from the film to obtain the stencil that will be used to design millions of other panels. This final stencil will then be carefully examined to ensure that it is free of defects.
The polyester screen is prepared for later use in printing the panel. Its preparation consists first of coating it with a thin layer of photosensitive emulsion and then gluing the stencil to it using vacuum pressure. This technique allows the stencil to be flattened to eliminate air bubbles and folds. The polyester coating is then exposed to quartz light for seven minutes to activate the emulsion, which will then harden, sealing the small holes in its fibres. This step will then end with a good rinsing of the screen.
While labourers work on the polyester screen, elsewhere in the panel manufacturing plant, other small hands carve the aluminum on which the model will be printed. Using a stamping machine, they round the edges of the aluminum plate and drill holes so that they can later fix the bolts used to position the panel on a pole. Then, the company name and year of manufacture will be annotated on the back of the panels to serve as a guarantee to their future buyer. The panels are then immersed in a chemical bath to remove all residues of substances used in their manufacture. They are then rinsed with water and soaked in an acid solution that makes the metal more resistant to weathering. The aluminum will then be filed with a film containing tiny glass particles that make the panel reflective to light. Finally, the panel will be cut according to the shape you want it to have, triangles, squares, rectangles, diamonds, round, or octagonal.
This step begins with a machine that pushes the ink used to print through a screen to the panel. The ink then penetrates through the open fibre holes of the shape, thus printing the colour background of the panel, but not being able to penetrate the plugged fibre holes, lettering and the outside of the shape. These parts will remain of a different colour from the shape, often white. The print is finally placed in a dryer for a few minutes.
All stencil films are carefully stored until they are ready for future use. In Canada, there are many stencils using symbols instead of texts. The most famous is the sign indicating the possible presence of caribou! As for the printed panels, they are placed in the oven for a last baking so that they can finally land on the side of our roads.
