Fisheyes in BoteCote Epoxy over Philippine Mahogany

[gwhastie]

May I have your advice please? Long story short....

For the past 3 years I've been building another Glen-L Crackerbox 16' powerboat - cold moulded hull skinned with marine ply and lamined in 48 x 16' strips of 3/16" Philippine Mahogany - glued with BoteCote and nailed with 18 gauge Raptor polymer nails.

I painted the raw hull in a slurry of watered down Timbermate natural finish woodfiller (to fill in the grain) then sanded it off and hand rubbed on thinned Jarrah Prooftint (thinned with metho). It was a perfectly smooth flawless surface - couldn't even see the nails.

Here's where my problems started... I've used Bote Cote two part epoxy as a top coat on other projects with great success, however after rolling on the first coat then tipping it off with a 3" foam brush...fisheyes started appearing everywhere...over the entire hull. I approached the local BoteCote distributor who checked my batch number with head office and advised that there must have been surface contamination present on my hull.

I washed down the hull with Acetone then scrubbed down the hull with hot soapy water and applied a second coat... with the same result to a lesser degree. I'm now up to coat #5 - wet sanding between coats to greatly minimise the fisheyes without sanding through into the stain...getting less and less blemishes each time. The timber grain looks superb. My aim is to achieve a deep clear finish (initially expecting to do 10 coats) as the end result but am wondering if I should switch to using multiple layers of clear varnish over this to finally eliminate the fisheye remnants - alternatively I could sand everything off back to raw mahogany and start again...but I'm buggered if I know how any contamination happened in the first place.

I'd welcome your collective advice please.

[gwhastie]

Well, I solved my own problem after reading countless posts on the internet and doing lots of experiments. I'm not sure what type of contamination was initially on my hull, but it is now fixed and the clear finish looks like glass...with no fisheyes.

I initially used a random orbital sander over the hull with 240 grit sanding disks to smooth the surfaces out slowly without going down to the stain for each of the nine coats of clear varnish that were needed rather than continuing with epoxy. Each sanding took over 2 hours and with every varnish layer, the fisheyes/dimples got shallower. Keep in mind that my hull started off looking like the surface of a golfball from the epoxy. The initial 4 layers of Bote Cote epoxy went on smoothly, but then it dried with deep textured dimples in it??!!?? I tried washing with soapy water, between sanding then wiping down acetone, but I couldn't prevent the epoxy coat from spoiling...so I switched to marine varnish.

The varnish I've used starts to tack up within about 60 seconds, so after lots of experimentation, I found the best result was achieved by brushing the varnish on quickly with a 100 mm foam brush...and it looks like glass, no brush marks or runs, with the timber grain looking superb. I used a bright light against the surface while varnishing, so I could see and eliminate any brushing blemishes before the surface tacked up.

Only four more coats of varnish then a cut and polish to remove any dust marks and then I can paint the bottom of the hull red, then turn it over to bolt in the engine. I'd have included pictures but can't seem to work out how to do it.

[Greg]

Great to hear you are finally having some success Gary.
There are some hints about loading images somewhere on the Board, but I will have to find them.
In the meantime, if you send the images you wish to post to me at nh35_stormy@bigpond.com, I can post them for you.

[screwit]

I had some sand paper that left a silicone residue on the boards and l think in the end l changed the paper more often so the Surface did not get to warm .

[Bob Vic]

I used a Scotchbrite buffing pad to buff the high gloss off each coat of paint before applying the next coat. I found this did little more than take of the shine and any specks of dust, so thoroughly recomend it. It also made it easier to see when applying the next coat. Twice, I also hit the hull bottom with wet and dry 1500 and a flexible rubber pad. It was surprising how quickly I could rub back the entire hull when I needed to cut a little deeper to achieve a flat surface.