On Mar 18, 10:24*am, Fred the Red Shirt
wrote:

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

It's like this: weight is an imperfect measure of mass, since it
introduces as a variable the gravitational pull of the Earth. Which,
as everyone knows, varies depending on ones location and altitude and
other factors. To cancel out these factors, the catalogs generally
specify a standard location at which the weight is valid. In this
case, the location seems to be Finland.

But seriously, I'm as mystified as you are.

As regards the weights of fiberglass parts, I've generally had good
luck just doubling the total cloth weight. That's generally what I do
to figure out how much resin to mix - I just take the cloth, weigh it,
and mix that much epoxy. It comes out a bit high for vacuum bagged
parts, and a bit low for soupy tooling layups, but generally puts me
in the ballpark.

Thanks, Bob K.