MWGF follows ASTM standards as a base line, and in fact uses stricter guidelines than those provided by the ASTM.
Based on machine capabilities and our own quality standards.
These guidelines allow for certain defects and variations in fabricated and non-fabricated products.
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The ASTM (American Society for Testing & Materials) sets standards for a variety of industries.
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The ASTM’s glass industry standards provide guidelines for allowable defects, quality, and how to visually inspect glass for:
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Flat glass
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Heat-strengthened and Tempered glass
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Laminated glass
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Insulated Glass
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Generally, use Quality 3 standards.
Visual Standards
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All visual inspections shall be made with 20/20 vision.
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View glass at 90° in daylight, but not direct sunlight.
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Stand at distance as specified by type of defect, focusing on the central area (center 80% of length and width) while looking through the glass and not directly at the surface.
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For chips: View chips from 1' away, without magnification, using localized lighting.
Visual Standards - Bowing
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Use a "true straight edge, wire, string or monofilament fishing line."
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Measure each of the 4 sides for overall bow on the concave portion of the glass within 1" of the glass edge and parallel to the edge.
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Also check the approximate horizontal and vertical centerlines for overall bow.
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 (¼")
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Glass thickness >6mm (¼") ≤ 12mm (½") may contain proportionally larger blemishes for the same minimum distances.
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Allowable blemishes for glass > 12mm (½") shall be determined by agreement between the buyer and the seller.
Allowable Distortion
Please contact MWGF for information on this subject if needed.
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
HS and Tempered Glass
Bow
Deviation in flatness spanning the entire pane of glass. Commonly seen in tempered glass and IGUs.
Allowed within reason. Not measurable on site or in an IGU. Positive and deflection is a natural occurrence with seasonal and barometric pressure cycling.
Distortion
Localized deviation in flatness that can look like ripples across the glass, or pockets of indentations.
Allowed and very common in tempered glass. Not measurable on site or in an IGU.
Stain Pattern
AKA iridescence; An optical effect that results from the tempering process appearing as a pattern of dark spots on the glass. The intensity of the issue increases when viewed at steep angles to the glass and with polarized sunglasses.
Allowed. This optical issue is characteristic of tempered glass and cannot be completely controlled. It will vary from pane to pane.
Laminated Glass
ASTM provides only basic guidelines for laminated glass – UNITS WITH TWO OR MORE LAYERS MAY CONTAIN MORE ALLOWABLE BLEMISHES
*Visual inspection process applies
*Blemish Guidelines for individual lites still apply
*Unites with more than 2 lites of glass may contain more allowable blemishes.
*Mirrors w/ silver on side 4 may contain more allowable blemishes. At this time MWGF cannot guarantee ASTM due to the inability to inspect. For more information contact MWGF
*ASTM Maximum allowable laminating process blemishes for overhead glazing's has different standers, contact MWGF if more information is needed on this.
CONTACT MWGF FOR SPECIFIC QUESTIONS RELATED TO LAMINATED GLASS
Lami Length & Width Tolerances
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Tolerances include cutting and fabrication of the individual lites and mismatch of the lites after lamination.
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For any piece over 75ft² please contact MWGF for length and width tolerances.
Lami Thickness Tolerance
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Always consult MWGF directly for lami thickness questions and concerns.
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Basic ASTM guidelines are as follows:
Lami Bowing
Insulated Glass
Stain Patter
An optical effect that results from the tempering process appearing as a pattern of dark spots on the glass. The intensity of the issue increases when viewed at steep angles to the glass
Allowed. This optical issue is characteristic of tempered glass and cannot be completely controlled. It will vary from pane to pane.
Fringes
An optical effect that appears as a faint, random, pattern resembling an oil stain.
Allowed. This is the result of having exactly matched thickness of glass panes in an IGU (less than 0.0001" difference in thickness).
Newton Rings
This is an optical issue that appears as concentric rings of rainbow colors near the center of an IGU that has its panes touching each other.
There is no industry standard covering this issue. Contact the manufacturer.
Color Uniformity
Readily apparent glass color variation from window to window, or within a window. It can be the result of the glass tint or glass coating.
Allowed within reason. Can be measured with special instrumentation if needed. Consult with manufacturer.
Fogging
A moisture or chemical deposit between the panes of an IGU.
Not allowed. Indicates seals have failed or outgassing of materials has occurred.
Sightline Infringement
An extension into the daylight opening of an IGU by the sealant, spacer, or area of coating deletion.
1/8" maximum
ASTM provides only basic guidelines for Insulated Glass, please contact Midwest Glass for special requests or more information.
IG THICKNESS CAN VARY +/- 1/16 please call if you need to consult on your IG.
IG Thickness Tolerance
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MWGF generally follows Guardian's guidelines for IG thickness.
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However, after testing MWGF tolerance for annealed & tempered is +/- 1/32"
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Bevels
•Based on machine capabilities
•Bevel width tolerance is +/- 3/32”
•Bevel corner tolerance on 1 ¼" and above is +/- 3/16"
Hole and Notch Guideline
LOCATION (See FIG. 1):
Min. distance from edge of glass: 6 mm (¼”) or 2x glass thickness, whichever is greater.
Min. distance between holes: 10mm (3/8”) or 2x glass thickness, whichever is greater.
DIMENSION (See FIG. 2 - 4):
Min. diameter of circular holes: 6mm (1/4”) or the thickness of the glass, whichever is greater.
Any other holes: Required to have fillets. Fillet radius must be equal to or greater than the glass thickness.
Hole Dimensional Tolerance: ±1.6mm (1/16”)
Notch & Cutout Dimensional Tolerance:
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±1.6mm (1/16”) for glass thickness less than ½”
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±3mm (1/8”) for glass thickness ½” or greater
Hold Tolerance
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Customers can request hold tolerance for a fee.
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For customer-supplied patterns, call MWGF if hold tolerance is required.
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MWGF does not accept partial patterns.
*Fabricated material is always + 0, - overall size
*All tolerances are up to the size noted.
Sources
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MWGF Terms & Conditions
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ASTM
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ASTM C1036
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ASTM C1048
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ASTM C1172
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ASTM C1376
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“When is a Defect Not a Defect? ASTM Glass Standards for General Contractors”
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Dynamic Architectural Windows & Doors
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Abridged Inspection Criteria - Fleetwood Windows & Doors
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ASTM C1048 Tempered Glass; Hole and Notch Guidelines - Syracuse Glass Company
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https://fgiaonline.org/pages/glass-standards-and-guidelines
Contact Midwest Glass Fabricators
For all quotes, orders or inquires:
Sales - sales@mwgf.com
248-889-7900
For all issues with existing orders:
Customer Service - csr@mwgf.com
248-889-7900
We accept quotes and orders by mobile text:
248-431-0895
OUR ADDRESS
Midwest Glass Fabricators
100 Transfer Dr.
Highland, MI 48357
AR Billing Address:
Midwest Glass Fabricators
PO Box 1509
Highland, MI 48357