Securing plastic into a face frame is done by solvent-welding lock strips to the top and bottom of the plastic. Lock strips should be fabricated to
the guidelines below, and are 6" [152 mm] shorter on each side, to avoid interference with the corner brackets. E.g. plastic length 12 ft., therefore lock strip
length is 11 ft.
.
If the sign height is greater than the sign length, use only a top lock strip along with vertical lock
strips
..
..........
Calculating plastic expansion and contraction
F x T x L x V = maximum expansion and contraction
Expansion - contraction Factor : F Material Thickness : T
Temperature variance in Fahrenheit : V Material Length : L
Expansion - contraction factor: Lexan 0.000375 Acrylic 0.000410.
A 20 ft. long piece of acrylic could expand and contract 1/4".
In general, for signs longer than 18 ft., cut the plastic shorter by 1/4" for every 6 ft. added length.
A custom-fabricated compensator may be required to overcome material
limitations
.