Epoxy and graphite powder "seams"?

Seagreen

Seagreen

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Epoxy and graphite powder \"seams\"?

I'm making a cockpit sole out of Iroko veneers on 12mm ply, and I've heard of a technique where, rather than using sealant as false caulking, epoxy coloured with graphite powder to turn it black, is used instead. This would have the great advantage of making the sole stronger and a bit more proof against hard wear.

Can anyone point me in the direction of powder suppliers, relative quantities etc?

Given the small quantities involved, could I powder my own artist graphite and charcoal sticks to achieve the same result?

TIA.

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Re: Epoxy and graphite powder \"seams\"?

I might have thought that lamp black would be easier to find. I have in the past bought a very fine black grout for tiles that would probably do, or black powder watercolour paint.
 
Re: Epoxy and graphite powder \"seams\"?

Just found a lot of info from WEST and Robbins on this very topic. Marinestore sell the stuff for £4.99 online, so I think my search has ended, but any advice or experience of problems would be very welcome.

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Re: Epoxy and graphite powder \"seams\"?

[ QUOTE ]
This would have the great advantage of making the sole stronger and a bit more proof against hard wear.

[/ QUOTE ]Are you sure?

Surely soft bouncy things wear less than hard rigid things.

On my mate's boat the teak decking has worn and the sikaflex type stuff is standing proud.

It might make your deck wear more evenly.

P
 
Re: Epoxy and graphite powder \"seams\"?

[ QUOTE ]
Just found a lot of info from WEST and Robbins on this very topic. Marinestore sell the stuff for £4.99 online, so I think my search has ended, but any advice or experience of problems would be very welcome.

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[/ QUOTE ]

Take note of the volume added to the resin and reduce the quantity accordingly or the cure will rapid or even exothermic.

When adding materials to epoxy rein stick with closed cell type materials like silica or ground cured epoxy, avoid open cell materials that may reduce the waterproof and bonding properties.

Keep the air as dry as possible during the curing, under 72% humidity and above 20*c is good.

Hope this helps.

Avagoodweekend......
 
Re: Epoxy and graphite powder \"seams\"?

Cheers. Thats good advice as my experience with epoxy has been "varied"...

I once used old resin that had been stored over-winter on the boat, and the stuff went exothermic so quick I dropped the pot with the heat - sizzled nicely for 10 minutes.
 
Re: Epoxy and graphite powder \"seams\"?

[ QUOTE ]
Cheers. Thats good advice as my experience with epoxy has been "varied"...

I once used old resin that had been stored over-winter on the boat, and the stuff went exothermic so quick I dropped the pot with the heat - sizzled nicely for 10 minutes.

[/ QUOTE ]

If you warm old resin (stand cotainer in hot water) and give it a remix it might be OK, you need to make a test item first.

To avoid overheating when mixed, always use wide shallow containers, Ice cream 2 litre containers a good. Only mix small batches, more work less risk and less loss.

Avagoodweekend......
 
Re: Epoxy and graphite powder \"seams\"?

Graphite can give a silvery cast to things, lamp black may be better.

Is there enough give in epoxy? Thought the point of caulking was to take up the expansion of the wood.

But then I know little about it, have plastic boat with plastic decks, and it still leaks!
 
Re: Epoxy and graphite powder \"seams\"?

The teak decks on my boat were caulked from new with epoxy and graphite. Not a great success, the wood wants to move epoxy won't let it, so cracked seams are the result. Main deck has since been relaid with sikaflex, still plucking up courage to tackle the rest.
 
Re: Epoxy and graphite powder \"seams\"?

My bruvs entire decks were laid with 4mm teak on black epoxy, on ply subdeck they never split or cracked, they are however now wearing through in hard wear patches, but they are over 20 years old now and been round the world twice. Whilst living aboard for 25 years.
 
Re: Epoxy and graphite powder \"seams\"?

You can get black pigment for SP resins from marineware in southampton. £6 for 500g I recall. It comes as pigment pre-mixed into resin so that the pigement is completly wetted out. The data sheet says mix to 10%.

Their tech support says you can add more (i used 15%), but it affects porosity slightly. He also said you can use powder paints, so that probably a yes to mixing your own.

If adding a pigment as powder, mix resin/hardener to the specified quantities, but if using sp pigemnt include the weight of this in the resin (becuase it is resin).

Bear in mind though, it is a nightmare to work with, ideally you need one person mixing/cleaning and one slapping it on. Use slow hardener. Also its very hardwork to sand.

SP do a pre pigmented black epoxy called Spa bond, which is generally used as an adhesive.

Using old resin is fine, but curing takes longer and its not as strong. Post cure with a heater will help. Most general purpose resins have long shelf life, low viscosity laminating resins dont.
 
Re: Epoxy and graphite powder \"seams\"?

There is a tecnique in the West bumph for laying decks with epoxy and black epoxy caulking but it refers to "veneers" of 3-4mm thick, I imagine that thicker decks would be subject to more thermal and moisture movement?
 
Re: Epoxy and graphite powder \"seams\"?

Thickened and pigmented epoxy only works with stable sub strates and thin veneers. There is a good section in the West manual on the technique which advises that it is not suitable for exposed surfaces and high wear. If you are using veneers 3mm or less then pigmented epoxy - does not need to be graphite, black pigment will do, is OK. However, just as easy to leave 4mm seams and fill with Sikaflex.
 
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