Fiberglass cloth weight vs 'finished' weight

Fred the Red Shirt wrote:
I was perusing the composite matierals in the Aircraft Spruce
catalog pages and noted that the fiberglass (and other ) cloths
are characterized by a unit weight, like 5.8 oz/square yard.
My naive assumption is that the cloth as purchased would,
on average, weigh 5.8 oz /square yd.

But some of the descriptions include a 'finished weight' which
is slightly different from the 'other' (nominal?) weight.

The weight of the final product after being impregnated with
resin and cured will vary with material and technique, but if
I assume an average specific gravity of about two for epoxy
fiberglass and use the nominal thickness of the cloth I compute
a weight of the resultant fiberglass sheet that is about twice
the 'finished weight'. So I'm assuming that 'finished' weight
does not refer to weight of a one square yard sheet of fiberglass
made from that cloth with epoxy or polyester resin.

So, can anyone enlighten me on what they do mean?

By 'finished' weight do they mean the actual average weight
as opposed to a nominal (rounded) value used to characterize
the cloth?

--

FF

No straight forward answer to that one Fred.
Way too many variables.

Biggest one is technique.

50:50 resin to glass is pretty tough to do by hand without
vacuum bagging and all that.
Even then, I thing 60:40 is abut the best I've seem.

Maybe using resin infusion process you could get 50:50.
I've heard claims of 30:70 - but never seen it myself.

Maybe some of the composite fellers can answer better.

Richard

Doesn't fg cloth have a "finish" applied to the fabric to facitlitate the
wetting of the fabric? Pat

patrick mitchel wrote:

Doesn't fg cloth have a "finish" applied to the fabric to facitlitate the
wetting of the fabric? Pat


Volan, IIRC

On Mar 18, 5:07 pm, cavelamb himself wrote:
patrick mitchel wrote:
Doesn't fg cloth have a "finish" applied to the fabric to facitlitate the
wetting of the fabric? Pat

Volan, IIRC

Aha!

I bet that's it.

Thanks.

--

FF