Deering Library Foyer Chandeliers
Northwestern University - Deering Library - Evanston, IL
The Lumenelle Solution:
1) Replace all Large Globes  – 18 pieces = 5 ” dia. x 11 ” height 
( Metal ring inside diameter =  6 3/8” ) 
2) Replace all Small Globes  – 36 pieces = 3 ” dia. x 11 ” height 
( Metal ring inside diameter =  4 1/16” )
3) Replace all Sleeves  – 18 pieces = 5 ” dia. x 4” height
( Metal ring inside diameter =  6 3/8” )
Before After
Problem:
Missing Glass Globes – 2 sizes
Missing Glass Sleeves
Solution:
Replace All Glass Sleeves and Globes
Problem:
Original Glass Has Become Fragile
Solution:
Replacements Are Borosilicate Glass
Notes: 
1) Client wanted heavy clear frosted (sandblasted? as opposed to milk glass to improve light transmission thus saving energy.
2) Sizes were matched to original glass pieces supplied by the client.
Three different materials were evaluated as replacements for the broken chandelier glass:
OPTIONS EVALUATED: CONCLUSIONS:
1) Borosilicate Glass    
Borosilicate glass combines high heat resistance with high stability against chemical aggressions. The long-term service temperature is around 450 C. Borosilicate glass is commonly used in laboratory glassware, cooking dishes, and bulbs for high-power lamps. Borosilicate Glass balances economy, appearance, and durability. As a result, Lumenelle suggests the use of sandblasted or etched borosilicate glass for the replacement globes. The glass would be a clear frost for maximum light transmission and would not have the milkiness of the original glass.  Lumenelle has provided a quotation accordingly.
2) Lead Crystal    
Lead glass has a high refractive index. Lead Crystal is commonly used in art glass and adornments on chandeliers. Lead Crystal is heavy and relatively fragile. Over tightening of the screws intended for holding the glass in place could relatively easily crack the lead crystal. Normally, the lead crystal used in chandeliers are either small pieces and/or large pieces are supported underneath. While lead crystal would be the most attractive of the three options, the chandeliers should be modified to provide support from below of the lead crystal pieces.
3) Polycarbonate    
Polycarbonate, an extremely strong plastic, is naturally transparent, with the ability to transmit light nearly that of glass. It has high strength, toughness, heat resistance, and excellent dimensional and color stability. Commonly used for plastic lenses for eyeglasses, vandal-proof windows and light globes.  Polycarbonate is capable of providing parts visually indistinguishable from glass. Three aluminum molds would be required making initial investment high. If all parts were the same or there were more chandeliers requiring replacement glass, this could be an attractive option in terms of cost. Polycarbonate has only fair chemical resistance and is attacked by many organic solvents. Polycarbonate is sensitive to ammonia, so glass cleaners like Windex should not be used on polycarbonate.
The resistance of soda-lime glass, the most common commercial glass, to sudden temperature changes is comparatively poor and therefore was not considered.
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