36-FL-GG FL CON Glass and Glazing Exam
| Structured Study Notes and Topic
Review Questions and answers latest
update
Question 1: In what year did Pilkington Brothers begin producing float glass, which
became the basis for all modern glass production?
A) 1923
B) 1945
C) 1959
D) 1971
Correct Answer: C
Explanation: The float glass process was introduced by Pilkington Brothers in 1959 and
revolutionized glass manufacturing. Prior to this, glass was produced using methods like
crown glass or cylinder glass, which resulted in uneven thickness and optical distortions.
The float process involves pouring molten glass onto a bath of molten tin, creating
perfectly parallel surfaces through the natural forces of gravity and surface tension. This
innovation remains the foundation of virtually all flat glass production today because it
produces glass with uniform thickness and exceptional optical clarity at a commercially
viable scale .
Question 2: How does the float glass process achieve its high optical quality?
A) By polishing the surface with diamond abrasives
B) By floating molten glass on molten tin to create parallel surfaces
C) By using centrifugal force to spin the glass
D) By applying a chemical etching process
,Correct Answer: B
Explanation: The float glass process achieves exceptional optical quality by allowing
molten glass to float on a bath of molten tin. The combination of gravity and surface
tension produces glass with perfectly parallel surfaces without the need for mechanical
polishing. The molten tin provides a perfectly flat, smooth surface upon which the glass
forms, and the process naturally eliminates distortions that were common in earlier
manufacturing methods. This method creates glass with uniform thickness and minimal
optical distortion, which is essential for architectural glazing applications .
Question 3: What is the primary purpose of an annealing lehr in glass production?
A) To rapidly cool the glass for tempering
B) To gradually cool the glass and avoid locked-in stresses
C) To apply Low-E coatings to the glass surface
D) To laminate multiple glass layers together
Correct Answer: B
Explanation: The annealing lehr is a critical component in glass manufacturing where
the glass is gradually cooled from approximately 1,000°F down to room temperature
under carefully controlled conditions. This slow, controlled cooling process prevents the
development of internal stresses that could cause the glass to fracture spontaneously. If
glass is cooled too rapidly, thermal stresses become "locked in" during manufacturing,
creating weak points that can cause breakage during cutting, fabrication, or thermal
stress events in service. Proper annealing is essential for creating glass that can be
reliably cut and fabricated .
Question 4: Tempered glass is approximately how many times stronger than annealed
glass?
A) 2 times stronger
B) 4 times stronger
C) 6 times stronger
D) 10 times stronger
,Correct Answer: B
Explanation: Tempered glass is approximately four times stronger than annealed glass
of the same thickness. This remarkable increase in strength is achieved through the
tempering process, where the glass is heated to approximately 1,200°F and then rapidly
cooled using high-pressure air jets. This rapid cooling creates compressive stress on the
surface and tensile stress in the interior. The compressive surface stress must be
overcome before the glass can break, providing the increased strength. This fourfold
increase in strength makes tempered glass the preferred choice for safety glazing
applications such as shower enclosures, doors, and storefronts .
Question 5: Which type of glass is created by sandwiching a transparent plastic
interlayer between glass lites?
A) Tempered glass
B) Laminated glass
C) Float glass
D) Wired glass
Correct Answer: B
Explanation: Laminated glass consists of two or more glass lites bonded together with
a transparent plastic interlayer, typically polyvinyl butyral (PVB) or ethylene-vinyl acetate
(EVA). The interlayer is placed between glass layers and subjected to heat and pressure
in an autoclave, creating a permanent, transparent bond. This construction provides
several important benefits: the interlayer holds glass fragments in place when the glass
is broken, reducing injury risk; it provides sound-dampening properties; and it can be
designed with specialty interlayers to provide acoustic damping, UV protection, or
enhanced security. Laminated glass is often specified for overhead glazing, hurricane-
resistant applications, and security-sensitive installations .
Question 6: When tempered glass breaks, it:
A) Forms large, sharp shards with pointed edges
B) Shatters into many small, relatively safe pieces
, C) Cracks but remains intact as a single sheet
D) Powderizes completely into fine dust
Correct Answer: B
Explanation: Tempered glass is engineered to break in a distinctive "dice" pattern,
shattering into many small, pebble-like fragments rather than large, dangerous shards.
This break pattern is a direct result of the tempering process, which creates a balance of
compressive surface stress and tensile interior stress. When the glass is broken, the
stored energy is released, causing the glass to break into small, relatively harmless
pieces. This characteristic is why tempered glass is classified as a safety glazing material.
The small fragments have dull edges, significantly reducing the risk of laceration injuries
compared to the large, sharp shards produced by annealed glass breakage .
Question 7: What does a damage weighted transmittance (Tdw) value measure?
A) The structural load capacity of glass
B) Protection against fading from solar radiation
C) The thermal conductivity of glass
D) The acoustic transmission loss through glass
Correct Answer: B
Explanation: Damage Weighted Transmittance (Tdw) is a metric that measures how
effectively glass protects interior materials from fading caused by solar radiation. It
evaluates the weighted transmittance of ultraviolet and visible light that can cause
damage to fabrics, artwork, flooring, and other interior furnishings. A lower Tdw value
indicates better protection against fading, as less damaging radiation passes through
the glass. Clear float glass has a relatively high Tdw of approximately 1.0, while specialty
glazing products with UV-blocking coatings or interlayers can achieve significantly lower
Tdw values. This is an important consideration for museums, retail displays, and
residential applications where fading is a concern .
| Structured Study Notes and Topic
Review Questions and answers latest
update
Question 1: In what year did Pilkington Brothers begin producing float glass, which
became the basis for all modern glass production?
A) 1923
B) 1945
C) 1959
D) 1971
Correct Answer: C
Explanation: The float glass process was introduced by Pilkington Brothers in 1959 and
revolutionized glass manufacturing. Prior to this, glass was produced using methods like
crown glass or cylinder glass, which resulted in uneven thickness and optical distortions.
The float process involves pouring molten glass onto a bath of molten tin, creating
perfectly parallel surfaces through the natural forces of gravity and surface tension. This
innovation remains the foundation of virtually all flat glass production today because it
produces glass with uniform thickness and exceptional optical clarity at a commercially
viable scale .
Question 2: How does the float glass process achieve its high optical quality?
A) By polishing the surface with diamond abrasives
B) By floating molten glass on molten tin to create parallel surfaces
C) By using centrifugal force to spin the glass
D) By applying a chemical etching process
,Correct Answer: B
Explanation: The float glass process achieves exceptional optical quality by allowing
molten glass to float on a bath of molten tin. The combination of gravity and surface
tension produces glass with perfectly parallel surfaces without the need for mechanical
polishing. The molten tin provides a perfectly flat, smooth surface upon which the glass
forms, and the process naturally eliminates distortions that were common in earlier
manufacturing methods. This method creates glass with uniform thickness and minimal
optical distortion, which is essential for architectural glazing applications .
Question 3: What is the primary purpose of an annealing lehr in glass production?
A) To rapidly cool the glass for tempering
B) To gradually cool the glass and avoid locked-in stresses
C) To apply Low-E coatings to the glass surface
D) To laminate multiple glass layers together
Correct Answer: B
Explanation: The annealing lehr is a critical component in glass manufacturing where
the glass is gradually cooled from approximately 1,000°F down to room temperature
under carefully controlled conditions. This slow, controlled cooling process prevents the
development of internal stresses that could cause the glass to fracture spontaneously. If
glass is cooled too rapidly, thermal stresses become "locked in" during manufacturing,
creating weak points that can cause breakage during cutting, fabrication, or thermal
stress events in service. Proper annealing is essential for creating glass that can be
reliably cut and fabricated .
Question 4: Tempered glass is approximately how many times stronger than annealed
glass?
A) 2 times stronger
B) 4 times stronger
C) 6 times stronger
D) 10 times stronger
,Correct Answer: B
Explanation: Tempered glass is approximately four times stronger than annealed glass
of the same thickness. This remarkable increase in strength is achieved through the
tempering process, where the glass is heated to approximately 1,200°F and then rapidly
cooled using high-pressure air jets. This rapid cooling creates compressive stress on the
surface and tensile stress in the interior. The compressive surface stress must be
overcome before the glass can break, providing the increased strength. This fourfold
increase in strength makes tempered glass the preferred choice for safety glazing
applications such as shower enclosures, doors, and storefronts .
Question 5: Which type of glass is created by sandwiching a transparent plastic
interlayer between glass lites?
A) Tempered glass
B) Laminated glass
C) Float glass
D) Wired glass
Correct Answer: B
Explanation: Laminated glass consists of two or more glass lites bonded together with
a transparent plastic interlayer, typically polyvinyl butyral (PVB) or ethylene-vinyl acetate
(EVA). The interlayer is placed between glass layers and subjected to heat and pressure
in an autoclave, creating a permanent, transparent bond. This construction provides
several important benefits: the interlayer holds glass fragments in place when the glass
is broken, reducing injury risk; it provides sound-dampening properties; and it can be
designed with specialty interlayers to provide acoustic damping, UV protection, or
enhanced security. Laminated glass is often specified for overhead glazing, hurricane-
resistant applications, and security-sensitive installations .
Question 6: When tempered glass breaks, it:
A) Forms large, sharp shards with pointed edges
B) Shatters into many small, relatively safe pieces
, C) Cracks but remains intact as a single sheet
D) Powderizes completely into fine dust
Correct Answer: B
Explanation: Tempered glass is engineered to break in a distinctive "dice" pattern,
shattering into many small, pebble-like fragments rather than large, dangerous shards.
This break pattern is a direct result of the tempering process, which creates a balance of
compressive surface stress and tensile interior stress. When the glass is broken, the
stored energy is released, causing the glass to break into small, relatively harmless
pieces. This characteristic is why tempered glass is classified as a safety glazing material.
The small fragments have dull edges, significantly reducing the risk of laceration injuries
compared to the large, sharp shards produced by annealed glass breakage .
Question 7: What does a damage weighted transmittance (Tdw) value measure?
A) The structural load capacity of glass
B) Protection against fading from solar radiation
C) The thermal conductivity of glass
D) The acoustic transmission loss through glass
Correct Answer: B
Explanation: Damage Weighted Transmittance (Tdw) is a metric that measures how
effectively glass protects interior materials from fading caused by solar radiation. It
evaluates the weighted transmittance of ultraviolet and visible light that can cause
damage to fabrics, artwork, flooring, and other interior furnishings. A lower Tdw value
indicates better protection against fading, as less damaging radiation passes through
the glass. Clear float glass has a relatively high Tdw of approximately 1.0, while specialty
glazing products with UV-blocking coatings or interlayers can achieve significantly lower
Tdw values. This is an important consideration for museums, retail displays, and
residential applications where fading is a concern .
