Allowable Blemishes
Quality Standards
Allowable Blemishes - Flat Glass
Point Blemish *
Blemish size: <1.2 (3/64")
Blemish size: ≥1.2 (3/64") < 2 (5/64") allowable w/ minimum separation between blemishes of 24"
Linear Blemish
Blemish intensity & size: Faint or Light & any size
Blemish intensity & size: Medium & ≤75 (3") allowable w/ minimum separation of 24"
Chip or Shell
Chip depth ≤ 50% of glass thickness
Chip width ≤ glass thickness or 6mm (¼"), whichever is greater
Chip length ≤ 2x the chip width
**v-chips not allowed in any circumstances
Intensity
Detection Distance:
130" - HEAVY
39" - MEDIUM
8" - LIGHT
<.2 - FAINT
*Values are for glass thickness ≤6mm (1/4")
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Glass thickness >6mm (1/4") ≤ 12mm (1/2") may contain proportionally larger blemishes for the same minimum distances.
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Allowable blemishes for glass > 12mm (1/2") shall be determined by agreement between the buyer and the seller.
*Contact MWGF For Guidance.
Allowable Blemishes - Coated Glass
Allowable Blemishes - Mirror
Mirror Glazing Quality (similar to Quality 3) for cut size
*Central area is considered center 80% of length and 80% of width centered on the lite. The rest is considered the outer area.
Point Blemish *
Blemish size: Central & outer area <0.3mm allowed
Blemish size: Central area ≥0.3mm < 0.5mm allowable w/ minimum separation between blemishes of 12"
Blemish size: Outer area ≥0.3mm < 0.8mm w/ minimum separation between blemishes of 12"
Blemish size: ≥0.8mm < 1.2mm w/ minimum separation between blemishes of 60"
Linear Blemish
Blemish intensity & size: Faint allowed
Blemish intensity & size: Light ≤75mm (3") > 75mm allowable w/ minimum separation of 24"
Chip or Shell
Chip depth ≤ 25% of glass thickness
Chip width ≤ 25% of mirror thickness or 1.6mm (1/16"), whichever is greater
Chip length ≤ 2x the chip width
**v-chips not allowed in any circumstances
Intensity
Detection Distance:
over 60" - HEAVY
24" - MEDIUM
8" - LIGHT
<8" - FAINT
Allowable Distortion
Please contact MWGF for information on this subject if needed.