Fairing

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propgun
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Fairing

Post by propgun » Fri Apr 06, 2018 10:43 am

Have something odd going on with my fairing at the moment.

Applied compound two days ago. Crazy weather in GA means that the epoxy (Raka 2:1 medium hardener) was applied at about 70F, had a temp rise of up to probably 80f in the afternoon, then cooled to about 38F overnight. Mix was already warming by the time I had it all on, last tbsp or so was actually unusable due to tackiness. Pretty standard behavior for this stuff in my experience.

Go to sand it yesterday. Rather than getting the superfine powder that I’m used to I’m getting crumbs and a difficult time sanding. Figure maybe it isn’t cured as I can leave a very slight fingernail print in the dips that had found their way in. Back off and figure I’ll try again tomorrow.

Try again this morning and same deal. Forming tiny crumbs instead of fine powder. Once again it got pretty cool overnight, but two days should be more than enough cure time even at low temps. It’s a 2:1 mix so it’s pretty hard to mess up and I had good pot activity. Any guesses?



propgun
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Re: Fairing

Post by propgun » Fri Apr 06, 2018 10:47 am

Looks like this
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Jaysen
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Re: Fairing

Post by Jaysen » Fri Apr 06, 2018 11:22 am

Could be a cure issue.
Could be a mix ratio issue.

Best bet is to try to warm up the hull a bit to encourage a cure or wait a bit for warm weather to get it for you. If it hardens after a bit of warming count yourself lucky.

If it is a mix issue then you have to pull it all off. That's a PITA. The only way to know is to hope it's a cure issue and see if it never hardens after a bit more time has past.

Until then, I'd leave it alone.

Hoping its a cure issue.

cape_fisherman
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Re: Fairing

Post by cape_fisherman » Fri Apr 06, 2018 1:56 pm

If convenient, pull it outside into the sunlight. Drape plastic over if you can...black works wonders.

fallguy1000
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Re: Fairing

Post by fallguy1000 » Fri Apr 06, 2018 6:05 pm

That is called corning or corns.

From uncured varnish or just about anything that is not or did not or will not cure fully. You cannot have that in your finish.

Try the black plastic for a day or so.

If soft and you can scrape it with a chisel; remove it all with chisel.

My guess is you had a poor mix. Happened to me and man what a pita.
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viewtopic.php?f=12&t=62495

propgun
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Re: Fairing

Post by propgun » Wed Apr 11, 2018 9:08 am

After a week still seems to be doing it. Temps still consistently pretty low. Not sure how it was an issue this time as it was kicking in the pot pretty quickly and applied on a warm day. Gonna keep sanding away at it and see what happens I guess. Pretty thin layer I applied so at this point removing it and fairing it are pretty much the same beast.

fallguy1000
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Re: Fairing

Post by fallguy1000 » Wed Apr 11, 2018 1:14 pm

Try using the sharp edge of this chisel at 90 to the hull. It will almost do nothing on hard epoxy, but peels the soft stuff well. It is fairly easy to gauge the work. Soft epoxy under paint will fail later. Fix it now.

You had poor mixing or had a measure error.
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propgun
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Re: Fairing

Post by propgun » Wed Apr 11, 2018 1:38 pm

Oddly enough I went out there earlier and went at it with 220. Still crumbing, so I went to 120 and it started sanding normal after it broke through the surface. Went over entire sole/deck and then went to 220 again and it was sanding normally.

Took it way down anyway, basically off. It’s hard like it should be. Can’t leave a mark with anything but a nail.

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