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Security Mirrors

Quick Tips #379

Using mirrors to help ensure a safe, trouble-free environment is good practice. When positioned appropriately, security mirrors can alert personnel of danger or theft. These mirrors are also useful in factories where foot and forklift traffic can cross paths, in offices where blind intersections and corners exist and at front desk/office locations that must be able to view normally blocked access areas. Security mirrors come in dome or convex configurations. The most commonly asked questions that apply to security mirror selection are what type of mirror, convex or dome style, what material of construction should be selected and where the mirror(s) should be placed for maximum viewing.

In order to choose the correct safety mirror you should be aware of the differences between both convex and dome style mirrors. Here we will take a closer look at both convex and dome mirrors, what they are best used for and how to determine what mirror will be best suited to your application.

Convex Mirrors

If an application calls for the need to view objects in some detail further away than 18', then a convex mirror is suggested. A convex mirror has a curved mirrored surface that allows for the reflective surface to project toward a light source. Convex mirrors reflect light outwards, they are not used to focus light, and therefore act similar to that of a standard mirror. Convex mirrors form a virtual image of reflection since the focus and the center of curvature are both imaginary points inside of the mirror. When trying to view and pinpoint a particular area, use a convex mirror. Since the lens of a convex mirror is curved less than that of a dome style mirror, the image in the convex mirror appears larger and less distorted. Convex safety mirrors allow for 160 degrees of vision, and can be used to view at an angle to reduce accidents around blind corners and doorways. As an example, convex mirrors are effective when viewing aisle traffic in a store or warehouse.

Convex mirrors are offered in circular or round rectangular shapes. Round rectangular convex mirrors are an ideal choice where hanging in low ceiling areas is necessary. Convex mirrors come in several materials and can be used for both indoor and outdoor applications.

Dome Mirrors

Dome safety and security mirrors offer a panoramic view of an area. Typically for indoor use only dome mirrors help eliminate blind spots and increase visibility at a broader angle than convex mirrors. Dome mirrors are available in full, half, and quarter dome models. Dome mirrors are effective when used to view wide areas where the objects need to be clearly view are no more than 15 to 20 feet away. A dome mirror lens is curved more than the convex mirror lens. The curvature allows for a wider angle of vision. Dome mirrors provide an infinite reflection; however, the further away a person is from the mirror the smaller the objects will appear. If the selected dome mirror is too small or positioned too far away for observation, the objects will appear so small that they are virtually unidentifiable. This is due to the curvature of the dome lens and the relatively short height/depth ratio on a dome mirror. The larger the mirror, the larger the objects will appear.

Quarter Dome Half Dome Full Dome
Quarter Dome Half Dome Full Dome


  • For small offices and “L” shaped hallways, a 90 degree “quarter dome” mirror can be used.
  • When viewing blind corners and “T” intersections, a 180 degree “half dome” mirror can be used.
  • For areas that require visibility at a four-way intersection or visibility from all angles a 360 degree “full dome” mirror is a best option.

Choosing the Correct Mirror Size

It is important to be able to select the right size mirror for the area it is expected to be used in. A mirror that is too small will not provide good viewing distance and visibility.

A good rule of thumb in selecting the correct size of security mirrors is the larger the mirror size, the larger the image will appear. As an example; if viewing a particular area with a 12" mirror, it will be a much larger image with a 36" mirror.

When determining the size of convex mirror to select for a location, a good rule of thumb to remember is, one foot of viewing per each inch of mirror. As an example, if planning on placing a convex mirror into an area that is expected to view 25 feet, then select a convex mirror that is 26” in diameter.

The following are factors to take into account when choosing the right dome mirror:

  • The distance in feet you will be standing or positioned from the mirror
  • How far away from the mirror are the objects you wish to view (distance in feet)
  • How clearly you need to see the objects reflecting in the mirror. Do you need to just make out movement, or do you need to see clearly enough to recognize objects or people in greater detail?
  • The larger the mirror, the larger the objects will appear in the mirror. Full domes offer the most robust view, followed by half domes, and then quarter domes.
Quarter Dome Height/Depth* Maximum Distance to Clearly See Objects 15' Away from Mirror
18” Qtr. Dome Mirror 9” 6’
26” Qtr. Dome Mirror 10.625” 8’
32” Qtr. Dome Mirror 13.5” 10’
36” Qtr. Dome Mirror 16.5” 12’
48” Qtr. Dome Mirror 19” 16’


*Height/Depth is the measurement from the bottom to the top of the dome.

Half Dome Height/Depth* Maximum Distance to Clearly See Objects 15' Away from Mirror
18” Half Dome Mirror 8.25” 6’
26” Half Dome Mirror 10.125” 11’
32” Half Dome Mirror 13.875” 14’
36” Half Dome Mirror 15.5” 16’
48” Half Dome Mirror 18” 24’


*Height/Depth is the measurement from the bottom to the top of the dome.

Full Dome Height/Depth* Maximum Distance to Clearly See Objects 15' Away from Mirror
18” Full Dome Mirror 8.25” 9’
26” Full Dome Mirror 10.125” 13’
32” Full Dome Mirror 13.875” 16’
36” Full Dome Mirror 15.5” 18’
48” Full Dome Mirror 18” 24’


*Height/Depth is the measurement from the bottom to the top of the dome.

Flat Panel Mirrors

For overhead distortion free viewing flat panel security mirrors provide optimum vision. Ideal for use in a suspended ceiling or as a ceiling panel insert. These mirrors are capable of offering a viewing of an immediate area. This type of mirror can be used for an overhead observation area or with a security camera. Simply replace the existing acoustical ceiling panel with the mirrored panel.

Inspection Mirrors

For inspection and viewing under and around vehicles, machinery and equipment, inspection mirrors offer features such as telescoping poles, with flashlight attachments, wheels and pivoting heads that can be angled to see into hard to reach areas. Inspection mirrors can be used indoors as well as outdoors.

Mirror Construction Materials

Safety and Security Mirror Information

Choose a mirror with the lens and backing that suits your application.
Acrylic: Lightweight, strong and shatter-resistant. Plastic: Lightweight. For indoor or covered outdoor use.
Scratch-Resistant Acrylic: Special coating hardens surface to keep surface smooth and resistant to scratching. Galvanized Steel: Weather-resistant. For indoor and outdoor use.
Glass: Easiest to clean, highest reflectivity. Hardboard: Strong. For indoor or covered outdoor use.
Polycarbonate: Strong, virtually unbreakable, and shatter-resistant. Zinc: Chemical– and weather– resistant. For indoor and outdoor use.
Stainless Steel: Highest corrosion resistance and superior strength.  


Commonly Asked Questions

Q: What is the difference between an Indoor Mirror and an Outdoor Mirror?
A: Typically outdoor mirrors will be convex; Grainger offers both indoor as well as outdoor convex mirrors. The material that the mirror is constructed of will determine if the mirror should be used outdoors or not. Certain materials cannot withstand the elements. It is best to review the materials your convex mirror is constructed out of before deciding to mount the mirror outdoors. Additionally, dome mirrors are intended for indoor use only.
Q: How high should I mount my security mirrors?
A: Recommended mounting height for security mirrors, in most cases is 8 to 10 feet. For low overhead clearance mounting, a rectangular convex mirror can be used.
Q: How should I clean my security mirrors?
A: Proper cleaning and caring for your security mirrors will keep the mirror in good shape for viewing. In order to avoid scratching your mirror surface, and to keep the mirror in good quality condition, it is best to contact the manufacturer for instructions on cleaning the mirror.



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(Rev. 5/2014)

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Please Note:
The information contained in this publication is intended for general information purposes only and is based on information available as of the initial date of publication. No representation is made that the information or references are complete or remain current. This publication is not a substitute for review of the current applicable government regulations and standards specific to your location and business activity, and should not be construed as legal advice or opinion. Readers with specific questions should refer to the applicable standards or consult with an attorney.

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