Fibreglassing work

[degrom]

I would definatley reccomend gelcoat, as you get a very good finish on it, and you can sand and buff imperfestions out of it.

Thanks for all the info!!!!

Regarding the Gel coat... Any idea where I can get a Get coat spray gun. I have seen the once with the disposable cups on the net,but nothing local yet.

[lordandrevv]

well, if you rip the glass in the rith shapes, you could even make it out of 450g with a bit of an eye for it. but seriously i dont think you need smaller than 230g. if you need some of that i can get you some pretty cheap from work.
just remember to use plenty of small ripped pieces where the surface is very uneven, and let the glass soak up the resin a little bit before you start rolling it...

[lordandrevv]

the fibreglass supply shops should have them in store (not sure what companies you have in welly). you can get away with using a slightly bigger ordinary spray gun and thining the gelcoat down. You can thin it with acetone as long as you dont use to much or 2 pack thiners. Remember to put styrene wax in the gelcoat if you are using it as a topcoat (don't have to in a mould). There is also a product called Patchaid (made by Nuplex, also can be found at Composite Supplies ltd) that replaces wax and gives the gelcoat better qualities when you use it as a topcoat.
I like gelcoat because you can sand out imperfections, and its very hard. eg had a very nice $70 000 four winns boat at work once, that had some scraches on the black part of the deck. Smaller one polished out, but the larger ones i sanded out, and slowly working my way up though diffrent grade wet and dry sandpapers, couple of compounds, and bit of polish, and a 7" grinder with a buffing pad on, you couldn't tell that they were ever there, and the scraches were faily deep, but not gone through the gelcoat obviously. Spent at least an hour doing that boat lol
The best way to gelcoat a mould up, to make a unit out of it, is still by brush i reccon tho.
Any other questions feel free to ask
Andrei

[imdying]

Yeah, I've made previous molds out of chopped up CSM alright, this is my first fully flanged up super mold, so I want it to be as good as I can get

Normally I wet the mat out on some newspaper first, get it well soaked and then lay it up... tried using whole pieces when I started, that was a bad idea

[lordandrevv]

yeah, you can wet it out first and put it on, or put some resin on the job, put the glass on it and then with a wet brush (resin wet that is) make it soak up a bit more from top and bottom, doesn't really matter as long as it is wet :-D

anyway, good luck with your mould man, any questions feel free to ask

[imdying]

I find that, even on a thoroughly cured mold (2 days at 50 degrees), if I work the glass around (with a brush or roller) on the (waxed and PVA'd) mold surface (gelcoat), it makes the gelcoat soften up, which if the gelcoat is too thin, causes the resin to attack the plug (assuming the plug material is susceptible to that). Seems to me that the less mucking about and 'playing' with it, the better.

[lordandrevv]

really shouldn't affect the gelcoat...make sure you get a bit of gelcoat on the plug/mould, if its to thin it's not good.
oh and by the way gelcoat is really resin with colouring agents and few other little bits and pieces, so its not that different.
Not sure if this is how you do it, but the best way to make things is tho put down the 1st layer of glass, let it harden (doesn't have to be fully cured) and then put the rest of layers on. The reson for this is not to allow heat buildup from the strong reaction, as it can deform (not stick to the mould/plug) and this is even more likely to happen if the gelcoat is spread to thin. You can get away with more layers from the begining tho

[imdying]

Yeah, doing that on the molds, but the carbon bits are laid up all at once and vac'd in a bag.

It appears that if the gelcoat is brushed on thick enough, it doesn't have enough mass to encourage the reaction, and it doesn't appear to cure. Since I've ensured that I brush it on nice and thick, I've had few problems.

[lordandrevv]

Yeah, doing that on the molds, but the carbon bits are laid up all at once and vac'd in a bag.

you making carbon parts using vacumm? awsome

It appears that if the gelcoat is brushed on thick enough, it doesn't have enough mass to encourage the reaction, and it doesn't appear to cure. Since I've ensured that I brush it on nice and thick, I've had few problems.

actually there is another explanation. gelcoat will never fully cure on the surface while in contact with air (well, over a long weriod of time it will). thats why on a mould, the side that is on the mould hardens while the exposed side is still a bit sticky. this is desireable since the sticky side lets glass stick to it better than if it was fully cured. This is also why you don't put on thin coats of gelcoat: it will not harden enough, since the air is getting all the way through it, and the gelcoat does not harden.
If you want gelcoat to harden all the way, you have to use styrene wax in it. Normally you want this on repairs, when you are brushing/spraying on the gelcoat and using it as a topcoat (so there is no glass to go on top of it)

[degrom]

Thanks for all the advice LordAndRevv....

Found a really nice example of what you can do with a bit foam and fiberglass.

The Opportunities are endless!!

[imdying]

Thanks for all the advice LordAndRevv....

Found a really nice example of what you can do with a bit foam and fiberglass.

The Opportunities are endless!!

Can recommend some other sites if you're interested. Fibreglass work is dead simple, it's the carbon stuff that's the pain, and that's mostly because there's so many steps, and because finishing the part after making it is severely limited compared to fibreglass which can be sanded.

[degrom]

Can recommend some other sites if you're interested. Fibreglass work is dead simple, it's the carbon stuff that's the pain, and that's mostly because there's so many steps, and because finishing the part after making it is severely limited compared to fibreglass which can be sanded.

Please do!!!!

I am sure there are plenty of us interested in this topic...

[imdying]

http://www.racingcomposites.net <-- very good
http://www.compositeforum.werksberg.com <-- also very good
http://www.fibreglast.com/VBulletin/ <-- not bad but full of spam
http://www.mci.i12.com/carbon/lost_foam.htm <-- might give you some ideas

Reading up on this stuff only gets you so far, you really need to give it a go. Fibreglassing stuff is pretty easy, seems like a good place to start.

All you need is:
- A litre of resin, polyester is cheapest
- 2 metres of chopped strand mat (CSM)
- 1 or 2 rollers
- Half a dozen 1" wide brushes (you'll waste them, so make sure they're cheap)
- A litre of acetone for cleaning
- A litre of brushable gelcoat
- Some MEK
- Some release wax
- Some PVA release agent (not PVA) - optional, but good insurance
- Heaps of sandpaper, from 40 grit to 2000 grit
- A lot of patience

[degrom]

http://www.mci.i12.com/carbon/lost_foam.htm <-- might give you some ideas

Liked this one a lot!!!

[imdying]

Yeah, not so crash hot on the details, but some interesting ideas.