Finisning and Fairing

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colinbrown
Posts: 98
Joined: Tue Jun 02, 2009 8:22 pm

Finisning and Fairing

Post by colinbrown » Wed Mar 02, 2011 11:57 am

Now at the fairing stage and need some advice on high build paints. Whos do I use and how many coats ? The only one I've seen so far comes in a 5lt two part tin and sold through Matrix. Anyone used the SP system?
Also the health and smell issue, any experience

BobC
Posts: 126
Joined: Thu May 28, 2009 1:27 pm

Re: Finisning and Fairing

Post by BobC » Wed Mar 02, 2011 12:37 pm

It's heavy stuff, so go easy.

I've always used SP Hibuild. In most areas, I would recommend that you mix it with microballoons to make a thick paste which you can then brush on. It's easier to sand with balloons in, and is a lot lighter too. Only use it neat for filling the dips in the weave, and then make sure that you get pretty-much all of it off again.

Also, give it plenty of time to dry, as solvent entrapment is a common problem. So leave it for a few days to dry-out properly before sanding, and then after sanding leave it again for a few days before putting anything else on top.

Oh yes, and make sure you wear a good facemask, the dust is very toxic and nasty (and it turns your snot grey).

Good luck

Bob
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colinbrown
Posts: 98
Joined: Tue Jun 02, 2009 8:22 pm

Re: Finisning and Fairing

Post by colinbrown » Wed Mar 02, 2011 8:34 pm

Thanks Bob, just what I thought, nasty stuff. I've not heard of adding micro ballons to the mix any idea how much to add. I was going to apply with a roller and do not want it to stiff. Anyone out there used any other product?

BobC
Posts: 126
Joined: Thu May 28, 2009 1:27 pm

Re: Finisning and Fairing

Post by BobC » Thu Mar 03, 2011 9:12 am

Where you have unfair areas (where you have overlaps of cloth for example), get the mix as thick as you can whilst still being able to brush it on (about the consitancy of toothpaste). Just keep adding bubbles until it's the right consistancy.

For the general weave, try mixing it up thick and spreading it on with a squegee or a credit card first, so more like a lightweight filler. Scrape it into the dips and then sand it back flat. You will then see any voids or low points, and then again if you need to build-up low areas, use the mix as thick as you dare and then flatten it back. Try to avoid putting it on neat if you need to fill or build-up an area. Only use it neat if you're going to sand it all back off again, and even then a small amount of balloons will reduce the weight and make it eaier to sand.

Use a long block for sanding/fairing (about 10in long x 4in wide) and use a whole sanding sheet wrapped around it.
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colinbrown
Posts: 98
Joined: Tue Jun 02, 2009 8:22 pm

Re: Finisning and Fairing

Post by colinbrown » Thu Mar 03, 2011 6:39 pm

Thanks Bob, you mention 2 different products there. Micro ballons ( which I think are brown ) and glass bubbles. Which should I use.? I have a small quantity of the brown ballons but a bucket of the white bubbles. I,m advised that te glass bubbles are much harded to sand . Any views please.
Not use to doing any fairing or filling, Johns moulds for the OD are gel coat perfect !

BobC
Posts: 126
Joined: Thu May 28, 2009 1:27 pm

Re: Finisning and Fairing

Post by BobC » Thu Mar 03, 2011 8:33 pm

Sorry, yes that was a bit confusing. You want to use the brown microballoons.
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SteveC
Posts: 550
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Location: United Kingdom

Re: Finishing and Fairing

Post by SteveC » Wed Mar 09, 2011 1:31 pm

Colin

West Systems do a filler called Microlight 410 which is incredibly light and can be mixed into a thick peanut butter type consistency. It can be spread out easily and will form a good edge. This is much easier to sand than silicon balloons and gives a very fine finish. It smells horrible.

One little technique I've found useful is that if you have an area which requires a lot of filler or is on a vertical surface, put the filler on and then put a piece of peel ply over the top. You can then put a roller over it or a straight edge and mould and push it down to give a nice flat surface as it gives the filler some support and a structure to bond to. Also the peel ply absorbs the sticky waxy bloom that comes off the epoxy after it's gone off and this is largely responsible for clogging your sandpaper. The textured surface you get means you can put another layer on top almost immediately after its gone hard without any further rubbing down and get a much better finish before rubbing back. Just make sure there are no air bubbles under the peel ply.
Steve Clarke (UK)
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Steve Clark
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Re: Finisning and Fairing

Post by Steve Clark » Thu Mar 10, 2011 9:20 pm

One of the advantages of using a prepackaged filler is that the stuff is all the same density, so it will sand evenly. If you start mucking around adding balloons , you will change that , and the fairing compound won't fair evenly. The filler loading also effects how the stuff shrinks, s0 it is useful to generate a standard batch size with a standard amount of stuff in it, whatever your additive of choice is.
Before microlite my preferred mix was 66% red microballons, 33% Cab-o-sil loaded 50-50 with resin.
Now i just use Microlight out of the bucket, and only care about the ratio when doing bunch of pretty big fills.
SHC
Beatings will continue until morale improves

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