Sealing ply without cancas or calico

[royce]

Hi guys, I've read with interest the sealing with calico in separate posts. Had I known about it I would have used it on my td. In ignorance I invented a method for myself on advice from a boat builder.

I used two part epoxy resin (30 minutes to dry stuff). I put this on with a broad spatula and worked it over the roof, sides and doors. I sanded most of ridges out until it was reasonable then used primer, undercoat and epoxy resin paint - Rustkill gloss finish actually - again on advice.

I've had a little bubbling where screws went in so sanded this off and used silicon on the screws as I replaced them (to seal cracks made by drilling and screwing the moulding on allowing water to travel under the paint). I don't know if this will do the trick but it seems to.

Also a fibreglasser told me he uses the epoxy resin but mixes it with acetone as a thinning agent to get it to soak into the timber ply (runs like water) and then a thicker coat on top (still thinned a bit) and then use the primer, undercoat and two coats of epoxy paint or, as he does, under fibreglass.

The advantage being when osmosis gets into the fibreglass the timber does not rot underneath, or so he says. Actually the ability of fibreglass to crack and for water to travel under it is one of the many reasons I avoid it.

[royce]

By the way, does anyone out there know if half bondcrete and water will seal the timber under varnish inside? I tried this out on advice to seal the lining inside (walls, ceiling and floor under the lino). I hoping it will prevent moulding from condensation inside my TD. Plus opening windows and ceiling vent for air flow should help. Be interested in your views for the future.

[groovy]

Bondcrete is water soluble an will soften and dissolve in the presence of water.

I you get water under the varnish, expect to see white patches from the boncrete dissolving and be prepared to then sand or otherwise remove the varnish so the ply can dry out.

Personally, I would have just used a good quality varnish, thinned for the first couple of coats as it soaks into the wood then used as directed on the can and does the job on a permanent basis.

Greg

[trodler]

Hi Royce and Greg.

You can use bondcrete as a sealer ,as long as it is not permanently wet or damp.
But the down side is that you can only paint over it with acrylic paints, so a final coat of varnish is out.

Cheers
Trodler.

[royce]

Thanks Trodler and Greg - much appreciated. I have done a final two coats of varnish over the top so I'll have to keep an eye on it and hope the ventilation prevents the problem in the first place. I'm disappointed as all the advice I received was when diluted with water it would soak in and make a seal in the timber.

While you guys are looking how will the two part epoxy go on the outside? I recall now I also bondcreted under that first and then did the epoxy on top some time later (It was in the garage during construction and had time to well and truly dry out). I had some bubbling as mentioned but located and fixed the source. I'd hate to have to rub back the paint so as to add calico.