Quickie Q2 Lite Construction Manual - page 28
strength and light weight. Even fewer are suitable for the hand layup
techniques used in the Q2. The glass cloth used in the Q2 has been
specifically selected for the optimum combination of workability,
strength, and weight.
.....
The glass cloth in your Q2 carries primary loads, and its correct
application is of vital importance. Even though doing your glass work
correctly is important, this doesn't mean that it is difficult.
.....
Two types of glass cloth are used, a bi-directional cloth
(5277BID), and a unidirectional cloth (5177UND). (Use the full part
number for ordering your cloth, but for simplicity the plans will use
only BID or UNI designations). BID cloth has half of the fibers woven
parallel to the selvage edge of the cloth and the other half at right
angles to the selvage, giving the cloth the same strength in both
directions. The selvage is the woven edge of a bolt of fabric as shown
in the accompanying sketch.