Finish Over Epoxy


CustomGlove

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First post here as a brand new wood-ruin-er. Hopefully graduating to woodworker.  I am making a set of corn-hole boards and they have gone out of control.  I ended up engraving sports logos on them and proceeded to fill with Enviro Tex Epoxy.  I picked it up at my LHS before I realized there were way better options for woodworking resources. After filling with the epoxy I covered with Minwax spar varnish and after 2 days the Spar is still tacky only over the epoxy.  It just doesn't seem to be curing. 

 

I found this thread.  So it seems like it is possible, but i'm not quite sure how to proceed at this point.

 

They need to be finished by Sunday so i know im pretty much in trouble at this point..  Any advice is appreciated.

 

Thanks!

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==>after 2 days the Spar is still tacky only over the epoxy.

What's the ambient temp of your finish area?

With epoxies (and most coatings in general), there's a difference between dry to the touch and cured.

EnviroTex makes about a dozen Epoxy-based adhesives/coating, which did you use?

How long after the Epoxy dried to the touch did you wait until top-coating?

Can you get yourself a small space heater and raise the temp in your finish area to 75-80F?

Were all the products fresh from the store?

 

With a little more info, we can give some useful ideas...

 

BTW: in the future, varnish finishes can be hurried along with temp and purpose-made varnish accelerator

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Thanks for the response! I threw the light on it so hopefully that will help.  My "shop" is a room in a walkout basement.  The temperature has been set on 70 but i'll see if I can get a heater to raise the temp more in that room.  Everything was bought fresh off the shelf about two weeks ago.  I used the "Envirotex Lite Pour on Finish" and let it sit for three days before I sanded it down smooth with the rest of the surface. The Epoxy was completely hard with no "tack" and sanded down easy.

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What is the advantage of varnish over epoxy? I was under the impression that epoxy is a final finish more durable than varnish.

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Exterior varnish adds additional UV protection.  Some epoxies have  UV inhibitors / absorbers built into the concoction, but it's not enough for a final finish :)

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What is the advantage of varnish over epoxy? I was under the impression that epoxy is a final finish more durable than varnish.

 

I didn't particularly like the look of the high gloss epoxy.  In addition to that though, it is considerably more expensive and would be to cover both corn-hole boards. These will be outside on occasion and the Enviro Tex Lite Epoxy is not recommended for use outdoors.  I am covering the rest of the wood and frame with Minwax Satin Spar Varnish. 

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How thick were the varnish coats on application?  Sounds like the epoxy cured but the varnish may have been put on a little heavy.  Also, did you sand between the varnish layers?  Did that first layer sand nice or was it a little gummy?

I only put on 1 coat.  I sprayed with an Earlex 5500 and the standard 2mm tip.  It is the first time I sprayed varnish with the gun, but I don't think it was too thick.  I thinned the mix with about 30% Mineral Spirits.

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==>Minwax Satin Spar Varnish

I've no experience with Minwax Varnish....

However, I do have experience spraying Epifnaes and Pettit. When you spray, you thin with a purpose-made thinner/accelerant. It's MS-based, but has other stuff added. Maybe BWT's got experience with MS alone. I suspect that's part of your issue... It'll dry, but it's going to take time...

 

At this point, heat is your friend. It's a non-linear curve... Raising ambient by even 5F will help a lot -- just don't go crazy and burn the place down...

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You beat me to it hhh :angry:.. Ha Ha..  IMO the tip was too large for varnish (which put it on heavy, but being on a flat surface you won't really notice it.  Had it been on a vertical surface you most likely would have more curtains than a speak-easy :P)..  Spirits is more of a brushing thinner, not suited for spraying as it dries too slowly.  If you're going to spray varnish the recommended thinner is xylene as it flashes off quickly.

 

More than likely the varnish will harden but it may wrinkle..  I'd give it a week or so in warm(er) conditions 70+ and see what happens.

 

I typically spray with a 1mm tip and thin 50/50 with xylene about 10-15 min apart (3 coats total then let cure and sand for the final coat).  That being said I brush whenever possible.  Each coat can be applied straight (no thinning) and you'll be left with a thicker film finish.  I actually get better results doing this over spraying (varnish)..

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I didn't particularly like the look of the high gloss epoxy.  In addition to that though, it is considerably more expensive and would be to cover both corn-hole boards. These will be outside on occasion and the Enviro Tex Lite Epoxy is not recommended for use outdoors.  I am covering the rest of the wood and frame with Minwax Satin Spar Varnish. 

 

Exactly what I would do as well (especially for something like this).  Gloss will show it's wear / tear; Satin will be much more forgiving.  A satin poly would be ideal as it's a very durable surface :)

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==> I actually get better results doing this over spraying (varnish)..

Wife has a brush-varnish project on right now that needs to get done asap -- used a bit (maybe 10%) of Epifanes spray thinner/accelerant to the mix... Works great. She's brushing thin coats and the accelerant shaves 8rs from re-coat time...

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You guys rock! Ill see what the increased temperature does and hit it with the brush next time.  I just got so antsy and bought this sprayer and now I have nothing to spray. All I've been doing is reading and reading and wishing I could start this project over or not at all.  I just want to make something I can put in the house.  These corn-hole boards are for my sister-in-law's wedding.  They both graduated from UGA and are getting married in Athens so I tried something unique and am paying for it.  Learned alot though on this project.  I was really excited to see how much information is available.  Of course I can't get enough of the podcasts either.

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your epoxy blushed.  when a two part epoxy cures it has a biproduct, a blush...a waxy film.  sanding only smears it around.  warm water a rag work, some say vinegar. others will go the acetone route.  there are non'blushing epoxies but not to be as ultimately waterproof as one that does form a blush.  varnish should stick, no problem with normal surface prep.

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your epoxy blushed.  when a two part epoxy cures it has a biproduct, a blush...a waxy film.  sanding only smears it around.  warm water a rag work, some say vinegar. others will go the acetone route.  there are non'blushing epoxies but not to be as ultimately waterproof as one that does form a blush.  varnish should stick, no problem with normal surface prep.

That sounds pretty much like what happened.  It was still tacky last night and they had to be presentable by Sunday since they are a gift. I had to work with what I had and dumped acetone on it and scrubbed off the finish.  I then threw down a quick coat of shellac and let it dry. I sanded the Shellac smooth and put on a coat of the Spar and this morning it was dry  :D.  

 

 

 IMO the tip was too large for varnish (which put it on heavy, but being on a flat surface you won't really notice it.  Had it been on a vertical surface you most likely would have more curtains than a speak-easy :P)..  

I was going to brush it on this time but still couldn't resist using the Earlex I invested in :ph34r: .  I played with the sprayer trying to get it dialed in as best as I could.  I was able to get a much better thin coating this time with the 2mm.  I am definitely going to get the finer tips so I don't have to spend so much time dialing it in down the road.  

 

If I have to do this again I won't be using this epoxy.  

 

Do any of you have a recommended epoxy that may be of higher quality for filling in an engraving?

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==>I've had great luck with West Systems

207 is the formulation for clear coating...

If you're going to cover with a high-solids UV varnish, then 206 will dry faster (what BWT uses).

As an alternative, you may consider CPES (what I use).

 

Smiths has an application note of varnish over CPES: http://www.smithandcompany.org/varnishpriming.html

BWT has a video on his site for varnish over 206: http://blip.tv/boatworks-today/varnish-and-epoxy-a-professional-s-wood-finsh-p1-5291496

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  • 6 years later...

Welcome, Hope!  I would suggest first that you check the mfg. instructions for the epoxy you used, as those will likely give you more accurate detail regarding curing time and compatible top coats. As a general rule, you will want the epoxy cured to the point that sanding makes powder, not crumbs. That time will differ by product. 

As a guess, I'd say sand with 180 to 220 grit before topcoating. But beware, spar urathanes are really meant for outdoor applications, where they offer some peotection against UV light, and are flexible enough to resist cracking from moderate wood movement in wet conditions (like boats).

A kitchet counter top may actually perform better with just the epoxy coating.

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