Thread 2947474

What's the most economical way to work with fiberglass?

Would you apply it as a coating onto some kind of bulk material like a surf board, build it as a lattice, lay it in an epoxy?

Let's talk about fiberglass

Another thing I can't work out is how much effort you'd put into mold it, vs how much effort you'd put into sanding and shaping it after its set.

>>2947475
>Another thing I can't work out is how much effort you'd put into mold it,
100%
>vs how much effort you'd put into sanding and shaping it after its set.
0%

>>2947474 (OP)
All the ways are cheap as dirt. There is no most economical because you're saving 10ths of pennies. And if you fuck up the forming you sand it and if you fuck up the sanding you form more etc.

There are only two considerations 1. What are you making and B how much if a fucking mess can things get?

Well for example you can buy fiberglass as sheets, in rolls, and there are any number of types of weave.
You can get fiberglass as fiber bats, or as threads.

And when you set it, it's usually a two stage epoxy, but what ratio of resin to fiberglass is the most economical?

And if it better to vacuum mold it, mold it under pressure, form it in the open. Do you do it layer by layer, or in one huge brick, or do you fiberglass layers then glue the layers together.

I don't understand all the incel posts on 4chan these days, go back to pol Incels, some of us are building things.

>>2947749
Resin and ply. Do whatever is the easiest until proven not working. Some people bulk up their resin with fibers and fillers, needless to say the dust is not good for the lung.

>>2947749
>but what ratio of resin to fiberglass is the most economical?
google it for me: 1.5 oz/sq ft of CSM needs about 3 oz of resin per square foot
in practice this means slather it on you're not going to weigh it out nor care in actual practice how much you need.

>And if it better to vacuum mold it, mold it under pressure, form it in the open.
well it fucking depends on what you're making doesn't it? obviously vacuum sealing is going to be more expensive because you need to buy the vacuum sealer big enough for the project and idk what the upside is when the benefits of fiberglass is forming it in place in the first place.

>Do you do it layer by layer, or in one huge brick, or do you fiberglass layers then glue the layers together.
as stated you form it, sand it, form more if needed, sand more if needed, form more if needed. it's like doing a plaster mask or those newspaper strips over a ballon. if you're talking a solid resin block you're fucking confused about using fiberglass. also you're fucking confused about using fiberglass in case that wasn't obvious. ditto "gluing" shit together, you're literally using resin what the fuck are you going to "glue" shit with? that's like making fiberglass pieces and then riveting them to other fibreglass, what the fuck would be the point?

fucking idiot

>>2947782
Good suggestion. Appreciated.
>>2947973
Benefit is typically a higher density and removal of air from the fiberglass.

I'm trying to repair an old lightweight fiberglass canoe that's got a small crack in it. Need to figure out what weight fiberglass cloth to use. I've got some random stuff that I think is like 9oz, it's far too coarse and heavy. I was thinking 4 oz, or maybe even 2 oz? Much harder to find though.
Advice?
The canoe itself is 14' long and should weigh around 35 lbs. It's nicely laid up fiberglass cloth, not chopped mat.

>>2949816
if you're still here then yeah, you definitely shouldn't use chopped strand mat for structural applications because the actual strength of it is not as good as something like a woven plain weave (checkerboard style) fiberglass
the type of damage you have makes all the difference in terms of how you should go about repairing it - is it a small hairline crack or is it a gaping shred like a dinosaur's claw went through it? is it on the side or on the very front? is the canoe entirely fiberglass or are there aramid sections?
the reason there are different weights to fiberglass cloth is so that you can just lay up one heavy layer instead of having to build up multiple lighter layers to reach that same weight, that's the general principle behind the different weights

i'm not a boat builder but i work with fiberglass and composites relatively often and if i were to do it, i'd start by using 180 grit to scuff up the surface around the crack to smooth it out and provide a mechanical key. clean it and then tape one side using teflon tape or flash release tape and start applying 4oz fiberglass to the side where the fiberglass is visible (i'm assuming it is) while matching the orientation of the weave and 2 layers should do the trick. if that doesn't feel right, put on another 4oz layer. for the outside, i'm guessing the other side that touches the water is gelcoated? that just means you'll have to apply probably a few layers of fiberglass on that side as well and i'd finish it with a tissue cloth, then an application of gelcoat with a brush and make sure you mix wax additive into that gelcoat otherwise it won't cure as it'll be exposed to air

remember - you'll need about 2.2x the cloth's weight in polyester resin to cover 1 square metre, so 1 square metre of 8oz will require about 495 grams of polyester resin
take that into account. i hope that answers everything, have fun!

>>2951925
oh, and depending on the surface finish, for the very last layer on top of the fiberglass i'd either use peel ply if it's a rough finish or a release film if it's a smooth glossy finish