Deck sheathing - how to do the edges?

[dur]

I am putting a new plywood cabin top on my Tamarisk in the next few weeks. Once on I plan to give it a layer of 250 g woven glass with epoxy resin.

I would like to carry the cloth about an inch down the cabin sides to make a decent seal but have always struggled in the past to get the cloth to stay correctly in position as the epoxy dries as it has a tendancy to try and spring back leaving air buubbles between the cloth and the wood. I would be very grateful to hear if anyone has any clever tricks for this operation.

When finished, there will be a varnished hardwood trim strip over the top of the glass edge but I don't want to epoxy this on.

 

[johnchampion]

I'm currently slapping epoxy and glass over everything apart from the coach roof on my Tamarisk, that's about the only bit that is still stuck down, the problem being that when it was first done the builder used polyester resin and not epoxy, cheaper but not good in the long term for this job as polyester ain't an adhesive.

I have never had a problem with "spring back" and the method I use is to first let a thin coat of epoxy go tacky on the substrate before applying the glass. The epoxy then holds the glass in place while it's wetted out. One of the problems that can be encountered is the use of too much epoxy when wetting out which means the glass floats on the surface rather than bonding to it. Also make sure the epoxy is warm so the air bubbles can get out when the wetted glass is squeegied because if the epoxy is too cold and thick it will hold the bubbles in suspense .

You could also use the edging strips to hold down the glass cloth but put a sheet of polythene between the strip and the glass. The epoxy wont stick to the sheet and it will act as barrier between the epoxy and the edging strip.

Did you get the pix I sent to your site of my Tamarisk?

 

[dur]

Thanks John

I have tried sticking the cloth to a tacky coat before - it has always then come unstuck when wetting the cloth out. If I let the tack coat go off with the glass on it, will it then wet out properly later?

I did get the pix thanks . Sorry I have not done anything with them yet - bit of a backlog with the website, the boat, the chores, the house, life etc.

 

[johnchampion]

I just managed to lose an answer I had typed for this so if you get two responses you know why. I don't think that it is a good idea to try to let the first tack coat cure and then wet out as even if it worked you would have an adhesive contact between everything and not a complete mechanical bond and there's every chance the wetout would not be particularly successful anyway.

When properly wetted out the glass should be more rather than less malleable and not have much spring in it unless you are trying to make too sharp a bend - is the edge rounded as glass wont attach well to a right angle and might well come off at that point.

I don't know about different types of epoxy difficulties for this type of job but I usually use West Systems allthough I've also used SP with no problem.

 

[tangomoon]

Are you making a decent size fillet to make a decent contour, instead of a sharp bend, for the glass to cover.

 

[alb40]

Ive never had a problem getting glass cloth to follow a contour.

Maybe you are apply too much resin. Use it sparingly for the first coat with the glass cloth. I then allowed mine to cure overnight before lightly sanding then applying two further coats of resin to fill the fabric wieve.

Alternatively, I would use a thinner fabric. The west system own brand fabric seems to work the best with tight curves.

 

[dur]

Thanks - I think I will radius the edges with the router which will help. It does mean I will have to build it back up afterwards - I guess with epoxy + filler.

 

[dur]

Thanks too - It is not so much a contour as a hard edge - so as suggested I will take the corner off it. It could be that I have been to liberal with the resin.

Now I just need some good weather for a month!

 

[Mirelle]

The bigger the radius, the better. One very good yard on the Crouch used a good inch and half radius on their glassed coach roofs.

 

[Adrian_Morgan]

Leave the epoxy until it's tacky, when it should stick better, or use another grade of cloth, one which drapes better. You can also hold the endge down with masking tape (stick it to the edge while the cloth is still dry. Wet out carefully and pull the cloth down with the tape. Or talk to SP Systems which supplies cloth and resin. They'll have a solution.