Glass weave style numbers, 120, 7781, etc.
Glass weave style numbers, 120, 7781, etc.
(OP)
Is there a reasonably authoritative source? There's a few snippets (e.g., Thayercraft.com have a bit of background although the descriptions are sometimes a bit odd) but surely these codes are agreed by cloth manufacurers (sometimes called converters)? Is there an AMS or ASTM standard for such things? If there's a standard do the numbers indicate the fiber material and any sizing as well as details about the weave style? Maybe my googling phraseology is just off.





RE: Glass weave style numbers, 120, 7781, etc.
These handbooks describe the different weave styles.
http://www.hexcel.com/Resources/DataSheets/Brochur...
http://jpsglass.com/jps_databook.pdf
RE: Glass weave style numbers, 120, 7781, etc.
They seem happy to standardize the end count in each direction and the amount of twist along with fibre size. Is there any measure of the tightness of the weave?
RE: Glass weave style numbers, 120, 7781, etc.
RE: Glass weave style numbers, 120, 7781, etc.
RE: Glass weave style numbers, 120, 7781, etc.
Regarding the weave tightness (I've always called it weave openness, but there's no industry accepted term that I'm aware of) I don't know of any common metric. I've seen obscure things like air permeability reported from time to time, but it's certainly not common and permeability would be a function of more than weave openness (e.g. areal weight). For me, the measurement has been experiential...seeing and using...samples...swatch books, etc. Of course, advice and insight from the manufacturer is always helpful. (just to make sure we're talking about the same thing...I use the term openness in describing the visual differences between the weaves in the attached photo)
RE: Glass weave style numbers, 120, 7781, etc.
Openness is probably the most appropriate term for what you describe. Most of the highly open weaves are leno weaves. Pairs if warp yarns are crossed over each other after every pick so they essentially pinch the fill yarns to hold them in place. Style 1659, which is pictured in jotunn's link is a common leno weave that is used in drywall joint tape. Binders are also to glue the yarns in place.
One useful test for openness of carbon is to fold some fabric over on itself at a 45 degree angle and counting how many pinholes of light you see per unit area.
RE: Glass weave style numbers, 120, 7781, etc.
Similarly interested in origins of the Glass fabric designations, which seem to be much better defined than carbon fabrics. As Noted the Mil-C-9084 spec which was originally from the 60's (?) specified several glass fabrics according to warp/fill, yarn construction, and areal weight. Interestingly (to me), what would now be a 7781 fabric was listed with a commercial designation of 181-75DE in an old version of the spec, so somewhere in the last 50 years the accepted commercial designation has changed.
also, reads as Commercial designations and nominal weights in my copy, so I don't think that's the origin of the commercial designations.
RE: Glass weave style numbers, 120, 7781, etc.
Reads the same in mine...good catch...thanks. Sometimes the fingers work faster than the brain...