Rhylsailer99
Well-Known Member
Is this ok to add to 6mm chopped strands to west system epoxy resin to fill in some small areas that would need more strength or should I just stick with colloidal silicon.
6mm chopped strands of fiberglass
- Thread starter Rhylsailer99
- Start date
Bobc
Well-Known Member
You can do, or another good way to bulk it out is with sawdust/wood pulp.
Boathook
Well-Known Member
West actually produce such a product. I think that they called it 'milled fibreglass'.
Bobc
Well-Known Member
You could just make your life really easy, and use Isopon P40
anoccasionalyachtsman
Well-Known Member
If it needs more stiffness then the silica would be okish, but if you need tensile strength add the fibres - not nearly as good as proper cloth, but better than nothing!
Tranona
Well-Known Member
Would not use chopped strands for filling - it is the wrong thing as you don't need the strength it adds and it is a pig to get a smooth surface. Use either silica and microbaloons or lghtweight fairing filler if you want to mix your own or International Watertite. The latter is easier to use and gives a good sandable finish.
TernVI
Well-Known Member
It's a good way to go for some things like chips in Laser centreboards.
Use glass bought chopped or cut it from tape or clotch not mat, as the binder in most mat is not right for epoxy.
It's a case of shaping it with metal tools, it should set quite rigid.
If you don't want the strength of glass, glass bubbles or microballoons may be better than silica for many jobs.
dankilb
Well-Known Member
I've found microballoons or similar still hold up best with some silica added - it seems to prevent the epoxy from sagging at a comparatively thinner consistency than with microballoons (or indeed milled/chopped fibres) alone. This is especially useful when you want a thin consistency for final fairing.
West low density fairing filler is a mix of (some sort of) balloons and silica, for this purpose, I believe.
geem
Well-Known Member
It really depends on the application. More detail would help. There are times when glass fibres in resin and silica is a good solution. Resin and silica is brittle on its own and will crack eventually in an application that needs some structural strength. If you are filling and faring something none structural then micro balloons are the way to go as its easily sandable unlike silica.
Stemar
Well-Known Member
If you need structural strength, go for the glass threads. It'll be seriously tough (impossible?) to get a really good finish on, but use it for the strength and a bit of epoxy filler to finish, which could be the same epoxy with microballoons, and you can get it as perfect as you need.
Rhylsailer99
Well-Known Member
Its at the top of an encapsulated keel where it joins to the boat a big chunk of gelcoat has come away exposing fiberglass strands and there is a gap like a void . I'll take a pic today of it.
anoccasionalyachtsman
Well-Known Member
Really doubt you need to add any strength there then - gelcoat provided almost none. Go for microballoons for easy fairing. Colloidal silica is hard work.
Rhylsailer99
Well-Known Member
Rhylsailer99
Well-Known Member
Right on top of where the keel joins to the boat it's encapsulated keel Cobra 850
anoccasionalyachtsman
Well-Known Member
That looks like a void in the laminate itself, and that you've lost a layer - as well as some gelcoat. I'd chop it out back to solid/tidy, taper the edges and fill it with patches of chopped strand mat.
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differentroads
Well-Known Member
Its the longer strands of glass mat that provide strength. That said, I always have a bag of chopped up small strands of leftover mat for just this sort of job - bulking out a filling with more strength than thickened epoxy alone will give me. Or P40 or Fibral body filler is even easier to work with and sticks surprisingly well if the old glass is cleaned with acetone and keyed.
It'll need fairing off. Epoxy thickened with microballoons is good.
It'll need fairing off. Epoxy thickened with microballoons is good.
geem
Well-Known Member
I would clean the old mat up with a flap sander on a grinder. If you cant get in to the void maybe use sanding discs on a Dremel. Vacuum the glass when done. Wet out the glass with unthickened epoxy. Mix in some micro-balloons and apply that to the hole. Sand back when hard and apply some epoxy primer ready for antifouling
Rhylsailer99
Well-Known Member
i have not got any micro balloons but have west system collodial silca ,micro fibres and fairing compound, i think maybe the silica would be best option.
anoccasionalyachtsman
Well-Known Member
Use the fairing compound, it's lovely to sand.
dankilb
Well-Known Member
West fairing compound is a ‘microlight’ filler (akin to - if not quite the same as microballoons) with some silica added. The brown stuff is the microlight, the white stuff is silica.
So you’ve already what you need, I think!
So you’ve already what you need, I think!