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Product: Glass front surface mirror

Substrate: Float glass, clear. Microcorrugation ≤ 20 µm/20 mm.
Selective double flat (1/4″ thickness only, sizes 32″x50″ and less): 1 wave per inch

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

Angularity: 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.

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

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°.

Adherence: 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.

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).

Hardness: 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

Deflect Type Defect Size Number Allowed Min Defect Distance
Pinholes &
glass defects
> 0.7 mm Not allowed
> 0.2 to < 0.7 mm Unlimited 50mm
< 0.2 mm Not evaluated but
no clouding
Scratches Width up to 0.08 mm Total length, Max
1/3 of longest edge
50mm
Width up to 0.01 mm Not evaluated

Staining: 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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