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Re: Material: fiber glass
By:Paul G. Jacobson
Date: 11/26/2001, 8:21 pm
In Response To: Material: fiber glass (steve hartmann)

: ok, figured out the epoxy. one ? what is the diffrence between woven and
: stitched non woven glass

woven glass is made like almost any other woven cloth. About half the strands run left and right while the other half run up and down. There may be some variations. For example, it is possible that narrow strands accounting for maybe 25 to 40 percent of the fiber content run up and down, while woven into these are thicker strands that account for the other 60% to 75% of the fabric. With more glass runningin one direction than in the other the fabric would be stronger, and be better at resisting forces in those directions.

They also sell glass "fabric" which is not woven at all. this can be a mat made up of shorter fibers that are interlinked and aligned in random directions. These shorter fibers add some strength, but the mat tends to absorb a lot of resin, so that strength comes at the expense of cost for the resin, and the weight of the resin.

Similarly, glass fibers can be sold as long strands. If you shop you can get a single strand, like a fine thread, wound on a spool, which is hundreds of feet long. Or, you can get hundreds ( or thousands) of these fine threads gathered together in a long bundle, looking like an untwisted rope.

If you take these long bundles and line them up on your loom as you might do to weave a fabric from them, but only weave a single fiber every 4 to 12 inches, essentially sewing them together, you get over 99% of your fibers running in one direction. This makes a very strong material in that direction (like a polyester rope is stronger than a piece of polyester fabric)

For building canoes and kayaks you generally want to use cloth that is "normal".
Since stresses can come from any side, and this has strength in all directions, it is a good match.

The thickness of the individual strands of glass, the number of strands in each woven yarn, the number of strands per inch and the pattern of the weave determine the weight, strength, surface finish and other properties of the glass cloth as well.

Generally, the strength of the cloth is directly related to the weight of the glass fibers in it. A 9 opunce cloth should be stronger than a 6 ounce cloth. There are some anomalies, though. Some of the types of glass used to make the glass fibers are stronger than others. Other fibers, like polypropylene, kevlar, nylon, dacron, spectra, and carbon cna be woven into glass cloth to change the properties, too. Or, you can get fabrics from these other fibers to use instead of glass cloth. A dealer can supply you with more trivia on these matters than you can decipher in a month.

hope this helps.

PGJ

Messages In This Thread

Material: fiber glass
steve hartmann -- 11/26/2001, 3:08 pm
Re: Material: fiber glass
Sam McFadden -- 11/26/2001, 9:28 pm
Re: Material: fiber glass
Paul G. Jacobson -- 11/26/2001, 8:21 pm