The best fairing method?

[Capt. Chris]

We have all the glass work done on our 28 Topaz project and I thought I'd bounce this subject off the pros. We are trying to achieve a yacht finish. The hull is epoxy and faired with long boards 30" and some longer homemades. We have some Duratec primer to bury the epoxy before the blue fairing primer goes on, unless there is a better way? Any input or methods would be appreciated. Thanks in advance,
Capt. Chris

[mastcolin]

Damn. No-one has replied! I was hoping to steal some ideas. I'm getting sick of sanding (or in current case, getting 8 chinese to do the dirty work)

Sorry. There is no alternative to hard graft here.

I'm not sure what your blue fairing primer is. Is this also a polyester?

Word of caution: Duratec is a Polyester. Your substrate is epoxy. I've seen funny things with the 2 (there is side reaction with any excess amine from epoxy and the polyester).

When you say 'bury the epoxy", do you mean epoxy filler mix or epoxy laminate? Are you not just better skimming on epoxy filler, sanding then using 545 to undercoat before topcoating?

It should presumably be reasonably fair to begin with. Just use the long battens to apply the filler in the 2 dimensions. Then sand...and sand. Just keep checking with batten. Duratec can be applied fairly thick and sands good so that will take out minor wibbles.

If you want good job, put on a sacrificial coat on top of Duratec ie gloss to see how it looks and sand this back if it is iffy.

Yep, it sounds easier said than done to get good finish. Sorry.


Good luck mate. 28 foot I presume? Try doing a 50m.

ps if you come up with any quick ideas, pm me. We'll buy it off you.

[Capt. Chris]

Mastcolin,
Looks like a magic method doesn't exsist yet. It was worth a try, right? It's funny you should mention about the poly\epoxy compatability. See my post in the material forum. Long story short, we are still watching the durotec peel off the transom! We used the blue vinylester fairing primer . It went nice and thick and sanded soooo easily! I guess we still had some blush, even after washing , sanding, scrubbing, etc. Now we're looking for an epoxy product that will sand like durotec. Any ideas? I don't have the luxury of 8 guys so the few I have seem to like sanding about as much as me.

Thanks Chris

[mastcolin]

Capt sir,

Just seen your story on Durotec/epoxy problem. Sorry I never saw this story earlier. It changes my original opinion from 'may have problems' to 'you will have problems.(you ain't first if that make you feel any better)

I agree with other comments on that post. Why bother with polyester ie gel over the epoxy? I'm not sure what gain is for risk.

Most of the painters who finish epoxy boats would skim on a filler mix over the laminate, then apply an epoxy sanding primer. This could be a spray fairing compound or just layers of primer. Then apply a urethane polyester over top.

The International spray filler Interfill 835 is good. Can apply 500microns dry and it stays easy to sand. The Awlgrip gets hard after a day or too and is pig to mix up to start with. If use use this you need to seal with undercoat (International Interprime 880 or Awlgrip 545)

Some guys just put on layers of Awlgrip 545 and use this to sand as it also stays good to sand for weeks. The Awlgrip high build primers go rock hard after a few days.

Happy sanding.

[Capt. Chris]

Thanks for the input!,
We started to use the durotec because it was so damn easy to sand. Now we are back on track with the epoxy. The only fairing compound we have used is West 410, but it's getting very exspensive. I wonder if anyone uses the Q-cell glass bubbles to mix with the 410 or just by itself to make a easy sanding fairing compound? I'm sure this is compatable with the epoxy and it will get a heavy coat of sanding primer on top before the color.

Thanks Chris

[michael-compwes]

....you can make a great and reletivily inexpensive fairing compound using epoxy resin(or vinyl-esther),power mixer(on a power drill),where you mix in almost as much micro-balloons(glass bubbles)/cabosil(antisag) as the resin will absorb.A higher ratio of balloons gives the softest sanding and greatest weight savings.
first use a notched-trowel to spread on to our surface,,use as long a board as you can,,ideally 1/4-1/3 the boatlength,but keep the pressure light or the hard-spots of bulkheads,etc will come out as indentations as the panels flex around them.
after fairing the notch trowel surface ,apply another layer of the same filler to fill in the notch layer,,,,,,,then start working with COMPATIBLE primers,as described above.

[Capt. Chris]

Thanks Michael