Newsletter - 2002 Archive

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BC Randonneurs
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A Safety Tip from 3M

Ian Stephen


I recently attended a 3M reflective products seminar and demonstration in Richmond. Technical representative Viola Hoo gave an interesting and informative presentation on retro-reflective products. No, this does not mean products designed to look like those from the '70s, rather they are products designed to return light to its source.

Hoo explained that there are two types of retro-reflective product, glass bead and microprismatic. Glass bead is the type on the Rando club's tights. It only reflects white. Microprismatic products use tiny prisms behind a layer of vinyl. Because the light is reflected through the vinyl layer, the reflected light is the colour of the vinyl. A familiar example of this is the reflective trim commonly used on panniers.

A problem with the microprismatic products occurs if water gets between the vinyl and the prisms beneath. Hoo said that this can seriously affect the performance of the product. The zigzag or crosshatched designs seen on these products are intended to prevent water migration between the layers. If you sew this type of reflective material to a piece of clothing or equipment, be sure to only sew along the edge to avoid creating an entrance for water into the body of the reflective piece.

Hoo said that if water does get between the layers, reflective performance usually does not return after drying. The holes that the water enters through are typically too small to allow thorough drying between the layers. To further complicate the problem, the vinyl reflective material may appear perfectly normal when viewed in daylight or in the home. To check for loss of performance from water entry the user must simulate the conditions under which the product works.

At night or in a dark room, shine a light at your vinyl reflective products and check that they still perform like they should. Ride safe.