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Old 05-02-2010, 19:09   #1
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Epoxy Help

Hi all

I have been doing a little project, building new cockpit locker hatches/seats and doors for my Vega. Made out of Brazilian cherry and some other flooring I had lying around. I decided that I would epoxy coat these before varnishing. To start with I donít have any experience with epoxy other than the ďfive minuteĒ type, but have worked with other finishes on wood and metal. I had sanded all the pieces to 220 before coating with West system105 and 207 hardener, applied not too thick (in my opinion) with small foam roller. Because I have to lay them flat to dry I can only do one side at a time. Some surfaces have two coats some have three with sanding to 220 before the third coat. So here is my problem, even after the third coat I am getting a lot of sink holes (donít know a better way to describe it) in the epoxy, sort of like ďorange peelĒ when you are spray painting. I have been very careful to avoid contamination after building and sanding in the garage I moved to the basement utility room for refinishing. No dust there and then wiped everything down with a tack cloth. After sanding the second coat (in the garage) I wiped it down with a clean cloth and a very little acetone. That being said some sections are coming out very nicely but others have imperfections. Is there some other technique I should be using or does it just take more coats, with sanding in between? Iíve included a few picís.

Glenn
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Old 05-02-2010, 19:21   #2
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Sand (120) between ALL coats and brush on. Throw that foam roller in the trash. If you have to use it tip with brush. Use slow harder. I swear I do not understand why so many think epoxy is the answer to everything. It will peel in the end.

Good luck
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Old 05-02-2010, 19:23   #3
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I used 105/207 over the entire cabin interior and I got a mirror finish after 5 coats.

Much of the first coast will soak in to the wood leaving small craters. Subsequent coats will gradually fill in those craters. I find it can take as many as 5 coats to completely fill in the craters. Sand between coats just enough to knock down the high spots....then rough up the surface with a 3M pad to knock any gloss off the low spots. Using the 3M pad I think is critical to stopping the orange peeling. Glossy surfaces seem to repel the next coat and roughed up surfaces seem to accept the next coat better. I see it as a similar difference between a drop of rain that hits waxed car paint versus hitting a cotton towel.

Orange peeling, which is different from gradually filling in the low spots, can also occur from using the wrong part B or when the room temperature is too low.

Is your room temperature high enough?
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Old 05-02-2010, 19:46   #4
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sailvayu

I used the epoxy to get a coating with a little durability varnish is too fragile for me, I tend to abuse things and I will try the brush.

David

Ok sand and more coats.

Thanks
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Old 05-02-2010, 19:47   #5
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David

yes temp is 65-67 degrees

Glenn
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Old 05-02-2010, 20:03   #6
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That temp should be ok. I would not want it any lower though.

Try the trick with the 3M Scotchbrite pad. Use the kind meant for painting, not for dishes. I like the dark red ones for doing this.


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Old 05-02-2010, 22:58   #7
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Agree with David. You are probably having trouble with amine blush. You should sand it wet (water dissolves the amine). To get a mirror surface, sand wet and hose some water over it and look how it runs off it... you will immediately see the trouble spots as little "rapids". Also, when wet it'll show you how it looks after the next layer is on.

Of course, after all that epoxy work you still need to paint or varnish it. Epoxy a little scrap and test your varnish on that to find if it's compatible. Find another varnish if not.

The best thing to do on bare wood is first vacuum it and next heat it just before the first layer of epoxy goes on. Use a heat-gun for that. You will get more penetration into the wood plus you prevent the bubbles.

The bubbles are caused by gas/air expanding with the rise in temperature by the curing epoxy. When you heat it first, you gas it before the epoxy comes on and it will actually be sucked in as it cools.

Do not use tack cloths etc. Wet sand, wash with water, let dry. no touching, no cloths, no thinner/acetone, no nothing. All that will just contaminate the surface.

click the photo for the complete album. We put a layer of glass on too but the rest is the same.



ciao!
Nick.
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Old 31-03-2011, 07:50   #8
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Re: Epoxy Help

I have a fiberglass boat, and I took off all antifoil from the hull.
I want to put an epoxy primer on top of the existing primer, but I have to know what primer there is on now.
What kind of test can I do to find out if the undercoat is epoxy or not, there must be a way.
Best regards. Willy
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Old 31-03-2011, 08:52   #9
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Re: Epoxy Help

Amine blush is a likely source of your problem.

"Cured epoxy
- Unless you're using WEST SYSTEM's blush-free 207 Special Clear Hardener, amine blush may appear as a wax-like film on cured epoxy surfaces. It is a by-product of the curing process and may be more noticeable in cool, moist conditions. Amine blush can clog sandpaper and inhibit subsequent bonding, but this inert substance can easily be removed.
To remove the blush, wash the surface with clean water (not solvent) and an abrasive pad, such as Scotch-brite(TM) 7447 General Purpose Hand Pads. Dry the surface with paper towels to remove the dissolved blush before it dries on the surface. Sand any remaining glossy areas with 80-grit sandpaper. Wet-sanding will also remove the amine blush. If a release fabric is applied over the surface of fresh epoxy, amine blush will be removed when the release fabric is peeled from the cured epoxy and no additional sanding is required."


see: Surface Preparation
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Old 31-03-2011, 09:15   #10
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Re: Epoxy Help

Quote:
Originally Posted by mbu745 View Post
I have a fiberglass boat, and I took off all antifoil from the hull.
I want to put an epoxy primer on top of the existing primer, but I have to know what primer there is on now.
What kind of test can I do to find out if the undercoat is epoxy or not, there must be a way.
Best regards. Willy
i use toluene to test epoxy primers,and xylene on barrier coat type primers.

xylene will cause a non epoxy to bubble and string when rubbed,and toluene will have no effect on an epoxy coating.

but generally aslong as the surface to be treated is well sanded,degreased and dry you will not have compatibility issues using an epoxyprimer.

added note xylene being an epoxy thinner and toluene being thinner for ablative type antifoulings,available from international paints,but cant remember the thinner number,look on the tin for content when buying.
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Old 31-03-2011, 09:42   #11
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Re: Epoxy Help

Quote:
Originally Posted by glenn.225 View Post
Hi all

I have been doing a little project, building new cockpit locker hatches/seats and doors for my Vega. Made out of Brazilian cherry and some other flooring I had lying around. I decided that I would epoxy coat these before varnishing. To start with I don’t have any experience with epoxy other than the “five minute” type, but have worked with other finishes on wood and metal. I had sanded all the pieces to 220 before coating with West system105 and 207 hardener, applied not too thick (in my opinion) with small foam roller. Because I have to lay them flat to dry I can only do one side at a time. Some surfaces have two coats some have three with sanding to 220 before the third coat. So here is my problem, even after the third coat I am getting a lot of sink holes (don’t know a better way to describe it) in the epoxy, sort of like “orange peel” when you are spray painting. I have been very careful to avoid contamination after building and sanding in the garage I moved to the basement utility room for refinishing. No dust there and then wiped everything down with a tack cloth. After sanding the second coat (in the garage) I wiped it down with a clean cloth and a very little acetone. That being said some sections are coming out very nicely but others have imperfections. Is there some other technique I should be using or does it just take more coats, with sanding in between? I’ve included a few pic’s.

Glenn
I wouldn't use a tack cloth--the wax on the cloth may be part of the problem. If you are wet sanding before coating then anime blush is not the problem either. I would block sand the finish you have back to a smooth condition with 180 grade wet or dry. Then clean thoroughly with acetone (the issue may be oil in the wood you are using). Then apply the epoxy and tip gently with a wide foam brush. by the second coat it should be dead smooth, like this:

http://bristol29.com/Projects/Exteri...adeshape16.jpg

That is three coats of epoxy and two coats of System Three clear gloss LPU, which is typically what I do for all the brightwork. I use 800 grade wet or dry wet after the second coat of epoxy and between coats of the LPU.

Good luck,

David
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