laying Fibre glass matting

[Leon01323]

Hey guys,

I keep seeming to have real issues with laying mat and getting air bubbles. The moulds i am doing are not big but to me they are fairly awkward in shape.

I keep getting bubbles that dont seem to disappear no matter how much i dab them with my brush and when i use a fibreglass roller it just seems to spread the matt or mess it up.

im using 450 gm mat Is this to thick for a first layer of a mould?

its beginning to annoy me and i tiered of messing up pieces

Thanks

[Brian2009]

Not sure about the size or shape of your application, but I use a "steel roller" after all the glass is placed. This roller does an excellent job of working the air out.

See item #T13-5976 on

http://fiberglasssupply.com/Product_...tingtools.html

[Leon01323]

Thanks for the reply,

my moulds look like this, i usual get air trapped around the little bits that stick out in the mould where the mat tends not to stick to the resin for some reason and comes away from the edge of the mould.



and make pieces like this:





i ordered a finned roller.. like the one you suggested and a penny roller for corners. will using 300gm matt instead of 450gm matt on my first layer help me get read of this problem as well.

what is the difference between 300gm and 450gm or any of them?

Thanks

[gonzo]

The difference is the thickness of the material.

[Leon01323]

Ah that's ok then. Should hopefully be easier to get the first layer in without air bubbles.

Thanks

[SamSam]

Some areas have such sharp bends that even mat won't go around them. Sometimes you have to come at it from two ways and butt mat up to it one way and butt mat up to it the other way. On sharp inside corners it sometimes works to lay a strand of woven roving in the corner first. Sometimes a milled fiber paste can be put in first to soften the radius.

[Leon01323]

Thanks for all the info guys.

what i tried today was when i did the first layer of fibreglass i used "tissue" matting so that i at least had a thicker area to stop the gel coat cracking if i got an air bubble.

also added less catalysis to my resin to give me a bit longer to work with it using the roller to roll out all the bubbles and double check.

piece that has just come out the mould was good only 1 or 2 small bubbles which im gunna fill and spray over the arch with white primer.

Thanks

[garrybull]

what i do is once the gel has gone off is on any edge where the mat is hard to get the air out is i put a thin layer of p40 filler which does the trick. don't build it up to much as it can become brittle and crack if its to thick.

[Leon01323]

Thanks Gary. Would it be bad if I was to do a layer of resin and let it dry? As in onto the gelcoat first. Then after that do the usual with the mat etc?

Want the process to be as easy as possible haha
Thanks

[garrybull]

probably wouldn't make much difference. when you do the fiddly bits do them in small pieces and take your time. i always use 450gsm mat for my first layer but if its a tricky bit i sometimes peel the mat apart to make it more like 225gsm mat so it works round the tricky bits easier. you'll find it easier with the p40 filler as well.

[Leon01323]

Yer defiantly a good tip with the p40 filler, do you sand it at all or smooth it ruffly with like your finger just so its less of a hard part.

i ordered some 300gm mat to do my first layer as ive found im struggling with the 450gm mat. have found you can tear it apart but sometimes it seems to fall apart lol.

P.s where do you buy your Fg products from? Im using CFS at the mo

[garrybull]

with the p40 i put it on with a small spreader then use my finger to smooth it out a bit. any spikey bits get a quick sand off before applying the mat but be gentle as you dont want break the gelcoat up

i use portsmouth fibreglass centre. they deliver locally and will courier stuff out too.
i have used cfs in the past. there quite a good company to deal with.

[Leon01323]

Ah cool cool will give that a go on the bits that stick out on my moulds see if I can get a better finish.

Sounds good. Yer they have been nothing but good since I've used them.

[garrybull]

how much are you paying for your resin? im looking about to see if i can get cheaper anywhere else. currently paying £390 for 225kg drum or £50 for 25 kg

[Leon01323]

cfs is more expensive than that. Its like $409 for 220kg and £57 for 25kg