Signwriting a cone

A sign writing entry – I don’t do many of those, but this took a bit of research, so here it is recorded. I was in the local hardware superstore a few days ago, and they were selling traffic cones of various sizes, and I thought it would be nice to get a couple and sign write them, which set me thinking about how to do it.

Obviously, any sign writing would need to be parallel to the base of the cone (or looking at it another way, perpendicular to the axis of the cone) which leads to the first problem, how to draw the text so that it follows the base. A cone can be constructed by rolling a segment of a circle, and the angle of the segment determines the “pointy-ness” of the cone. To add text to a cone, we must first get the segment that matches the cone we are signwriting. Its obvious that there is a ratio between the angle of the segment of the circle, and the angle of the cone, and the easiest way I found to represent it is as follows.

Measuring the angle of a cone may be a bit difficult, so I am basing my calculations on the radius of the cone at the level of the signwriting (lets call this R), and its distance down from the tip of the cone along the slanted sides (not down the axis) which we will call S. You may need to put a couple of straight edges on the sides of your cone to determine where the tip would be if it is a truncated cone, or conical fustrum!

We need to draw a segment of a circle with a radius of S, with an angle of T, where T is equal to 2*PI*R/S. Corel Draw and Adobe Illustrator both have options for drawing segments like this. If you want multiple lines of text, just add concentric arcs within the segment.

Next step is to add the text making it follow the arcs just drawn above, which again is a fairly standard option on both drawing packages. When text follows the arc, above the line, the tops of the letters get closer together, so you may need to change the letter spacing to make it look better. Obviously choice of fonts and type sizes is something you will adjust to fit onto the base lines you have drawn.

Ideally, the text should taper towards the top, so that spacing can be kept standard, but I can find no way to wrap text around a curve and add perspective at the same time. As traffic cones are pretty pointy, it is not a big deal, so I will ignore it for now!

BUT – and a big but – most vinyls will not stick to most good traffic cone’s plastic! Traffic cone plastic is very, very flexible, and contains a lubricant that helps the PVC molecules move over each other. This lubricant (one of the pthalate compounds) is present on the surface of the plastic and apparently leaches out too, so vinyl will not stick for any length of time. Cheaper cones such as the ones you buy in hardware stores etc may not have this substance and may be more prone to breakage, but try one before you promise to sign write 50 cones! The same goes for road side marker wands – those white u-shaped sticks with a red marker and a reflective strip, only not quite so much. A good aggressive adhesive as used on some reflective vinyls will stick quite well to these, and vinyl wrapped around them and stuck to itself will stay put for quite a long time.


Dave Glover is a director of Signs of Success Ltd. married to Lynn (the other director of SOS) with 3 grown up kids. We live in Whitby, in New Zealand. After 30+ years in IT as everything from Trainee Programmer to Project Manager, Dave now runs a Computer Maintenance and Sign Making shop near his home.

Posted in Sign Making

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