Technical specifications are below for Glass First Surface Mirrors. If you have any questions please contact us.

Product: Glass First Surface Mirror


Clear float glass. Microcorrugation ≤ 20 µm/20 mm. The 1/4″ thickness we stock is selective double flat at 1 wave per inch. 1/8″ thickness is approximately 8 waves per inch.

Spectrophotometric Curve Measured at Normal Incidence

enhanced aluminum wave chart


No less than 94% reflectivity for the visible region as measured with a Weston photronic cell with a Viscor filter and illuminated by a tungsten lamp supplying light at an angle of incidence of 22.5°.


No mirror coating will be removed by the cellulose tape test described here. The adhesive side of cellulose tape is carefully placed in contact with a portion of the mirror surface and firmly rubbed against it. It is then quickly removed with an action that exerts the highest possible stripping action.


Sizes and glass thicknesses available on request. A cutting tolerance of ± 1.5mm applies to all final dimensions.


Angular deviations allowed within dimensional tolerance.

Edge Finish

Coated side has unfinished edges. Caution: unfinished edges are sharp. Handle with care. Uncoated side has seamed edges:

  • Maximum 5 chips allowed per edge
  • Maximum chip length: 5mm
  • Chips may extend into glass surface for maximum 30% of the glass thickness
  • Edge fractures are not allowed

Edges chamfered as per drawing specifications.


Single-side coating: Aluminum with an interference coating for reflectivity enhancement, deposited by magnetron sputtering under a high vacuum.

Optical Requirements

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Corrosion Resistance

The mirror has no noticeable deterioration of the finished mirror when given a salt atmosphere in a thermostatically controlled cabinet for 24 hours at 95° Fahrenheit (35° Celsius). The salt atmosphere is created by allowing a stream of bubbles through a salt solution containing 1.5lbs (0.68 kg) per cubic ft of water.

Effect of Temperature

The coating is not effected by ambient temperature of -60° Fahrenheit (-51° Celsius)to 500° Fahrenheit (260° Celsius).


Film is not removed when the following test is applied: Clean dry cheese cloth bearing the force of 1 lb (566 grams) is rubbed against the coating 200 times.

Durability Requirements

  • Abrasion test, 200 strokes, 1lb (566 grams), with cheesecloth
  • Adhesion test with 3M 8981 Scotch tape
  • Humidity test, 48 hours, 95% relative humidity, 50° Celsius
  • Immersion test in salt solution, 37g/l, 24 hours at room temperature
  • Salt spray test to ISO 9227 NSS, 48 hours
  • Wipe test (20 cycles) with isopropyl alcohol, glass cleaner, acetone
  • Immersion test in isopropyl alcohol, acetone, 2h at room temperature
  • Cycling test (4 hours at 80° Celsius, 4 hours at -30° Celsius, 16 hours at homidity to ISO 6270 Part 1), 4 cycles
  • High-temperature storage (7 days at 100° Celsius)

Following these tests, the coating does not show any defects such as stains, delaminations, or pinholes The required minimum reflectance values are still exceeded after the tests.

Defect Standards

For all semi-finished products, a rim area of 5mm all around is excluded from the inspection

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Stains in the coating that are visible in reflected light at a light intensity of 1500 Lux are not allowed.

Visual Inspection in Reflection

  • The visual inspection in reflection is performed on a test location with a light intensity of 1500 Lux.
  • For the inspection, the mirrors are positioned in front of a black background. The incidence angle of the light source on the front surface mirror is approximately 30° to the vertical.
  • The coated side of the front surface mirror is toward the observer.
  • Before the visual inspection is performed, the complete surface of the glass is wiped with an alcohol-soaked cloth.
  • The visual inspection for surface defects (scratches, stains) and impurities is performed at a distance of approximately 70 cm.

Visual Inspection in Transmission

  • The visual inspection in reflection is performed in a light box with 1500 Lux.
  • The glass panel is placed in the light box so that the front surface mirror is positioned vertically with the coated side toward the observer.
  • The front surface mirror is inspected for coating defects (scratches, pinholes) from a distance of approximately 50 cm.

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