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Old 19-11-2014, 23:28   #46
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Wink Re: Thinning Epoxy to Penetrate Wood.

Great to hear that it's going well Mark. Yeap! If the epoxy has set on the tape it can become part of the new finish.
A tip when it comes to applying the polyurethane. You load the brush with poly and always work back towards the wet edge. Then tip off towards the new wet edge. Then load again work back to the new wet edge then tip off again. Done right it will eliminate runs as you won't be overloading at any one point.

Oh!! and just as your mother would tell you. Leave it alone and DON'T PLAY WITH IT.The varnish that is. If you do have a dryspot, a hair or a run you can fix that with the second coat.

Work fast and enjoy.

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Old 20-11-2014, 14:08   #47
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Re: Thinning Epoxy to Penetrate Wood.

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Originally Posted by sobraon View Post

2. Apply 2 or 3 thick coats of clear epoxy, wet on wet.

Gary,

Could you please describe "wet on wet" better?

I did about an hour between coats but because its a vertical fiddle a fair bit seems to have run down. The first coat had definitely not cured much at all by the time the next was going on.

How long between coats? When its still runny? Or when its fixed but tacky?


Thanks,

Mark
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Old 20-11-2014, 14:29   #48
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Re: Thinning Epoxy to Penetrate Wood.

On plywood edge grain, it only takes a minute or so for the edge to begin appearing dry. So you can re-coat, over and over, until it just won't soak up any more--sometimes 6-8 coats or more. On flat, vertical surfaces, you have to wait sufficiently long to re-coat so it doesn't sag.
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Old 20-11-2014, 14:33   #49
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Re: Thinning Epoxy to Penetrate Wood.

Wet on wet refers to ensuring a chemical bond as opposed to a physical bond.

After the coat has 'kicked' ie it is no longer liquid, but still wet, then add another coat. Since the first coat has not fully cured, the layers bond chemically.

If the coat is fully cured, then you have to sand to give the next layer some 'tooth' to physically bond to.

The chemical bond is stronger.

Don't try to add more while still liquid (before it kicks) you will make a mess.
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Old 20-11-2014, 14:37   #50
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Re: Thinning Epoxy to Penetrate Wood.

Quote:
Originally Posted by sobraon View Post
Great to hear that it's going well Mark. Yeap! If the epoxy has set on the tape it can become part of the new finish.
A tip when it comes to applying the polyurethane. You load the brush with poly and always work back towards the wet edge. Then tip off towards the new wet edge. Then load again work back to the new wet edge then tip off again. Done right it will eliminate runs as you won't be overloading at any one point.

Oh!! and just as your mother would tell you. Leave it alone and DON'T PLAY WITH IT.The varnish that is. If you do have a dryspot, a hair or a run you can fix that with the second coat.

Work fast and enjoy.

Garry
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My mother was an expert with Callahan's chilled varnish. I as a kid got the bottom paint and painting the bilge. My job didn't take any talent.

Just to see if anyone remembers the chilled varnish?
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Old 20-11-2014, 17:10   #51
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Re: Thinning Epoxy to Penetrate Wood.

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My mother was an expert with Callahan's chilled varnish. I as a kid got the bottom paint and painting the bilge. My job didn't take any talent.

Just to see if anyone remembers the chilled varnish?
The wonders of online search engines:

Varnishing in direct sun?
A trick for when we are forced to work in direct sun is to use varnish that has been chilled in the refrigerator. Keeping the can in an ice bucket prevents the varnish from warming up on the job. This means that cold varnish goes on to a hot surface and drys from within. Good Luck!
Jay
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Old 21-11-2014, 01:07   #52
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Re: Thinning Epoxy to Penetrate Wood.

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Could you please describe "wet on wet" better?
With epoxy the "wet" window is about four times the setting time. No excact time but you can wait untill the previous coat is not too sticky anymore. The back line is harder to define but if the perevious coat hasn't developed any amine flush yet you can do the second one without any further preparation. When all the coats needed are done you can make some aftercuring with heat (about 60 C to 70 C for a few hours) if you want to be sure of the bond and make the the epoxy coat a bit harder..
BR Teddy
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Old 21-11-2014, 01:29   #53
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Re: Thinning Epoxy to Penetrate Wood.

Wet on wet means the brush doesn't drag on the 'wet" surface, there is no amine blush and the previous coat is still soft enough to dent with a thumbnail.

Easy

Another test - if you can sand it, it's too late - it's no longer wet; if it's too soft to sand, it's still wet
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Old 21-11-2014, 05:55   #54
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Re: Thinning Epoxy to Penetrate Wood.

Mark,

Sorry I haven't replied earlier. The time difference makes it difficult, that and the fact that I have been busy running around Labuan all day.

Everyone seems to have their own interpretation of wet on wet.

What I was referring to was getting as much epoxy on as possible, as quickly as possible.

Normally as 'wotname' had said. If the brush doesn't drag the epoxy shouldn't sag. I normally just keep applying until I have all the epoxy I have mixed on the wood and not in the tub.

If it does sag don't panic. It simply means it will be easier to control the sanding in that area and you won't be sanding through to bear timber . It should fair easily enough the following day.

If the area isn't too big use a good cork block with the 120 grit rather than an orbital sander. It will be a lot easier to control the sanding this way. You will be suprised how quickly it comes off. On the radius-ed areas just use your palm with the sand paper. Believe it or not it is the most accurate way to do it.

Good luck mate.


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Old 21-11-2014, 06:05   #55
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Re: Thinning Epoxy to Penetrate Wood.

Thanks everyone.

While I am still doing that I need to do my saloon table whilst the boat is a bloody mess (I have just been getting new davits on too and ...well...).

The table is veneer, and Beneteau has used a spray polyurethane o it which goes into the grain but has not filled the grain.
So if I sand it off or strip it, I will be left with polyurethane in the grain.
There is nothing wrong with the coating now except its lost is shine.

Can I use the epoxy method OVER the old polyurethane? Smoothing the surface and increasing the gloss.


This would make things very easy for me.

Mark
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Old 21-11-2014, 07:10   #56
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Re: Thinning Epoxy to Penetrate Wood.

Mark, except on end grain such as plywood edges there is not any real benefit to thinning epoxy for what you are doing, the amount of penetration is minute on face grain, straight unthinned epoxy has great adhesion and has the benefit of filling the grain quickly, especially on open grain woods such as teak. On the table I would just sand it down an then build it back up with more urethane if that is what it already is. When i build a table with teak plywood i give it 2 or 3 coats of unthinned epoxy wet on wet before i even cut up the sheet because the veneer is so thin, (most teak plywood is crap with a ridiculously thin fancy veneer) at that point the grain is filled and there is plenty of epoxy to protect the veneer and to block down flat ready for varnish or polyurethane. Even though it is inside you still need a finish with uv filters or it will be damaged by the sun streaming in the windows.


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Old 21-11-2014, 07:33   #57
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Re: Thinning Epoxy to Penetrate Wood.

Mark,

Have you already sanded the Table?

Here are just a few old shots of some of the varnish work.

In the first photo the epoxy had been applied and dried. As you can see it isn't necessarily attractive. This particular piece bubbled a lot. It didn't matter as when it was sanded and the poly applied it was a good as all the rest. Some of the photos are pretty crappy as this was before I updated to DSLR.




It looks a whole lot better when the poly is applied.











Hope it is all going well.

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Old 21-11-2014, 07:55   #58
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Re: Thinning Epoxy to Penetrate Wood.

Fearing forum ridicule, I removed the polyurethane from the table...





Flat tables are easier to work on than anything else on a boat. That must be why YouTube How To videos always show the 'expert' working on a flat bit of wood.

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Old 21-11-2014, 08:17   #59
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Re: Thinning Epoxy to Penetrate Wood.

Mark,

The Polyurethane on the table may be difficult. The reason for applying the epoxy is to fill the grain and give depth to the finish. It really has little effect other than that. The polyurethane will seal out the moisture anyway.

I have found that the only safe method to remove varnish and polyurethane from veneered ply is to chemical strip and scrape with a tungsten blade.




For problem areas that the scraper couldn't get to I use the stripper with a stainless steel kitchen scourer rubbing with the grain.




If you sand you will f*&k it up. Guaranteed. You cant control the sander to know accurately how much varnish and how much veneer you have taken off until it is too late. You know the experience thing, yep I have f*&ked it up once or twice.

I am not sure what paint stripper you have available where you are. The stuff here in SE Asia eats through latex glooves in 2 minutes and is very effective.

If you think stripping is too big a task you may get away with a light hand sand to roughen the surface. Then apply polyurethane sanding sealer or straight polyurethane. If you try to apply the epoxy onto the polyurethane you may get away with it initially, however I think down the track you may find it fails.

Thai Stripper.




In Aus I was using this slightly greener option.



Just read that you have the varnish off the table. You will be good to go with the Epoxy. A little varnish in the grain shouldn't be a major issue. You were lucky, or Benetau Veneer is thicker and better than the Benetau critics will admit.

Good luck,

Garry
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Old 21-11-2014, 08:18   #60
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Re: Thinning Epoxy to Penetrate Wood.

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Flat tables are easier to work on than anything else on a boat. That must be why YouTube How To videos always show the 'expert' working on a flat bit of wood.

I also noticed that the youtube experts have a large workshop and $30,000 worth of fancy power tools to do the job while I'm working upside down in a tiny locker with a Dremel and a 20 year old pad sander.
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