Curb Number Pro

What Is Reflective Paint (and Is It a Good Idea for Curb Numbers)?

Reflective curb numbers are at the very least an intriguing idea and can be desirable for the right curb number application. If you’re unsure what reflective paint is, how to apply it, and when it’s actually a good idea, then read on. I’ve had lots of people ask about reflective paint and reflective curb numbers. So, I'll cover what reflective paint is here so you’ll have a clear idea of what it is and when it makes sense to use it. 

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What Is Reflective Paint?

Reflective paint is regular paint with a reflective quality. Reflectivity in paint is made possible by adding tiny spheres or flakes of material like glass, glitter, or another additive such as crystal that gives the paint a reflective quality. Reflectivity happens when light hits and bounces off the added material. This type of reflectivity is known as retro-reflectivity and can be very effective.

What Is Reflectivity?

There are actually three types of reflectivity. The three types are specular, diffuse and retro-reflective. For the purpose of this article, we'll only go into detail about retro-reflectivity. But first, let’s look at the traits of each type so we'll have a clear overview.

Specular Reflectivity

specular reflectivity is like the mirror image you get from water

The most common example of specular reflectivity is a mirror reflection. Seeing a reflection of the sky in calm water as seen in the above image is an example of specular reflectivity. This has nothing to do with reflective paint so we aren’t going into detail about it. But, now you know about specular reflectivity and what it is.

Diffuse Reflectivity

Light bouncing off a white painted wall and flying out in all directions is a perfect example of diffuse reflectivity. White and very light colored paint that ”brightens” a room does so because of diffuse reflectivity. The paint reflects the light that hits it and the rays of light are scattered all over the place. This type of reflectivity in paint is the most commonly experienced type of reflectivity in paint and it's easy to understand.

Light Reflectance Value, or LRV, is what measures the ability of a painted surface to reflect (or absorb) light. You may also hear about “Light Reflective Paint”, which is a phrase used to reference paint that has a high LRV. 

Retro-reflectivity

example of retro-reflectivity

Road signs, road stripes, speed bumps, and reflective tape are all examples of the use of retro-reflectivity. When a light source like your car headlights hit a surface that's painted using a reflective additive, like glass beads, the additive acts as a prism and reflects the light back in the direction of its source. 

Retro-reflective curb numbers may be the most common type of reflective curb numbers you will find, due to the wide availability of spray on reflective paint. Glass beads are also mixed into paint or sprinkled onto non-reflective or reflective paint that's still wet. 

Glass Beads

Illustration of close up of reflective paint

Glass Beads or "microspheres" come in a variety of sizes and shapes. In general, the smaller the glass bead, the “tighter” the reflectivity is. Said another way, the smaller the glass beads used in an application, the closer you need to be to the light source in order to see the reflected light. 

Stop signs, for example, use larger glass beads for wider visibility and greater shine. In curb numbers, using smaller glass beads makes sense since the most obvious purpose is from car headlights or a spotlight. The driver or other people in the car would need to be directly behind or to the side of the source light in order to see the reflectivity.

Almost all reflective paint contains glass beads. You can also buy glass beads separately, which can be mixed into paint or sprinkled onto the surface of wet paint.

Spray On Reflective Paint

ideal embedment of a glass bead in paint for best reflectivity

Reflective spray paint is semi-transparent and generally clear or off-white in appearance. It contains tiny glass beads. When you apply a very light coat, some of the beads will be exposed at the surface of the paint. When applied on top of another color (to make it reflective) it will also very slightly alter the base color and make it appear "frosted".

You probably already guessed that reflective paint with glass beads is retro-reflective in nature. You can read on the side of the reflective spray paint can to apply light coats. That's because if it becomes too “wet” then the reflectivity is diminished or eliminated. When applied too thick, the paint will pool and the glass beads will sink into the paint,

At least some of the glass beads need to be exposed for a light source to refract through the glass and reflect light.

As I mentioned earlier, retro-reflectivity happens when the surface can refract light back to the source. Those frosty little balls that sit on top of the surface of the paint are what refract the light.

illustration shows light refracted through a glass bead and bouncing back toward the light source.

Types Of Reflective Paint

  • Spray on reflective paint contains tiny glass beads mixed into the paint itself. The glass beads are very small and spray on reflective paint needs to be applied sparingly so the glass beads won’t sink into the paint too deeply. You also need to shake the can frequently since the glass beads are constantly sinking to the bottom of the can.
  • Reflective Safety Paint is a convenient brush-on paint containing glass beads but does not necessarily create a highly reflective surface. A light coat is required and even still, most of the glass beads in it will sink into the wet paint, and render them non-reflective. Extra glass beads are often included in your purchase along with a recommendation to sprinkle or spray them onto the wet surface.
  • Creating your own reflective paint can be a less expensive alternative to Reflective Safety Paint. Glass beads are mixed by hand into regular paint. Making your own reflective paint can help with the high price of reflective safety paint. Mixing it yourself will take experimentation and practice to get it just right.
  • Metal Flake  and Metallic spray paints are typically not used for  their reflective quality, although they can reflect light. Metal Flake paint is usually semi-transparent with micro sized metal flakes which make it "sparkle" when light hits it. Metallic paint has even tinier flakes to create a smoother finish designed to imitate a metallic surface.

 The kind of reflectivity you get from paint with metal flakes in it is specular because there is no refraction of light. The metal flakes do have a reflective quality though, so I thought it was worth a mention as reflective paints.

Is Reflective Paint a Good Idea For Curb Numbers?

It really depends on where the curb actually is and how reflective the homeowner wants their curb numbers to be. All reflective paint applications can improve curb number visibility at night.

In one scenario, where a house faces the end of a long street, highly reflective curb numbers can not only shine the address to cars coming down the road, but it can add a significant level of safety as well. 

Houses along the side of a street don't get too much benefit from reflective curb numbers since it needs a light source for them to reflect. Headlights don't aim to the side of a car. However, if someone is looking for house numbers with the aid of a flashlight or spotlight, reflective numbers can arguably help them find the house number faster than without reflective numbers.

For houses along the side of an average neighborhood street, reflective curb numbers are, in my opinion, more of a preference than a necessity.