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air bubbles

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BWD
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Re: air bubbles

Postby BWD » Tue Jun 11, 2013 2:12 pm

Looks cool!
Re: sanding and hot coats, on my last twin tip the temperature dropped too much during the "hot" coat and the result is a little lumpy with fish eyes. But it rides great so I haven't even sanded it , much less recoated it,
yet.

sinker
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Re: air bubbles

Postby sinker » Wed Jun 12, 2013 7:28 am

Thanks BWD. Same issue for me with hot coating, fisheye spots are bountiful on the board. Not really sure why and eventually said forget it and took it to the water. The board rode so well that I already have two other cores nearly ready - rails are poured and want to replicate the smooth ride of that board.

zfennell
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Re: air bubbles

Postby zfennell » Wed Jun 12, 2013 1:33 pm

fish eyes are the result of surface tension.

epoxy adhesives make poor 'paints' and tend to fish-eye, particularly if there are any contaminants on the substrate you are coating (fingerprints, dust,compressor oil etc)

epoxy paints typically have a surfactant additive to allow the resin to 'sheet-out'
and some adhesive manufactures sell additives for their resins to do the same thing.

a piece of release film can smooth out large areas, but the edges will still need sanding.

always good to wash, sand, wash, dry and apply in dust free area.
use clean gloves
maybe thin the resin (heat or solvent)
maybe find a surfactantt for your resin

...but be prepared to sand like the rest of us.

nice looking board

mattthieu
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Re: air bubbles

Postby mattthieu » Wed Jun 12, 2013 1:53 pm

any brand of epoxy pased water resistant clear varnish/paint/gloss/coat someone could recommand for finishing ??

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bay surfer
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Re: air bubbles

Postby bay surfer » Wed Jun 12, 2013 8:23 pm

Not a fan of Clear coating with Epoxy, Not UV resistant at all, gets frosted fast, you can wet sand smooth and wash then apply some fast dry Poly for shine and UV resistant surface or just wax for a semigloss surface. Screw the Spar stuff your not leaving the board out 24 hrs a day forever. Always wash Epoxy surfaces with soap and water before putting Poly on, or it may not dry.

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Re: air bubbles

Postby mattthieu » Wed Jun 12, 2013 9:15 pm

so, polyester clear coat ? wood stuff ? boat stuff ?

shure, weet sand till 600 grade then wash w soap then coat ( dry before !! ).

what about car clear coat ??

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Re: air bubbles

Postby BWD » Wed Jun 12, 2013 9:41 pm

They mean polyurethane not polyester.
Polyester is a type of resin.
There are epoxies with UV resistance, too.
They are as good as using the kind of polyurethane you can get from a spray can.
2 part polyurethanes are better, but you need special equipment and respirators to use them.
And fixing any dings means sanding it off anyway.
So I would say keep it simple and use a UV resistant epoxy, and also use a surfacing agent in the hot coat, and hot coat above 21 degrees C. Sand as much as you like or polish if you want, but spraying on polyurethane mainly makes your board 200-500g heavier imo.

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Re: air bubbles

Postby scklandl » Sun Jul 07, 2013 12:20 pm

Air is from squeegeeing in resin into fibers, no matter how airless your resin is once you pour it onto cloth and start saturating the cloth bubbles will be created. It's not from the wood.

Solutions:
vacuum infusion (PITA)
Precured sheets (not much experience)
Pneumatic press, (vacuum pressure is air pressure it will never overcome air)

My solution has been perforating the core. Works very well, costs nothing, adds little time or complexity to the process


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