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Epoxy nightmare

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Forum topic by Patrickgeddes14 posted 09-15-2019 12:35 PM 629 views 0 times favorited 18 replies Add to Favorites Watch
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Patrickgeddes14

190 posts in 327 days


09-15-2019 12:35 PM

So I’ve never had problems with epoxy or getting ratios right but this time I think I’m mucked. I did a flood coat on a big slab and there was still a few even spots so I threw another coat on. It was a brand I’ve never used and the amount was smaller than I’ve ever used. I let it cure overnight and it’s still pretty tacky. Whatever the problem is, (probably ratio), I need to probably try and remove the entire attempted coat. I’m gonna wait a day or two just to see, but other than a pressure washer or high powered water, I’m not sure how I’m going to be able to get this mess off. Thoughts?


18 replies so far

View Gene Howe's profile

Gene Howe

11853 posts in 3940 days


#1 posted 09-15-2019 01:39 PM

Aggressive scraping then belt sand. Re pour.

-- Gene 'The true soldier fights not because he hates what is in front of him, but because he loves what is behind him.' G. K. Chesterton

View ArtMann's profile

ArtMann

1435 posts in 1327 days


#2 posted 09-15-2019 01:42 PM

The thing that is most tacky is your crude and unnecessary use of an expletive in your first sentence. Your post says more about you than it does about epoxy.

View bondogaposis's profile

bondogaposis

5542 posts in 2862 days


#3 posted 09-15-2019 01:42 PM

I would try heating it first, you might be able to get the epoxy to kick off.

-- Bondo Gaposis

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Patrickgeddes14

190 posts in 327 days


#4 posted 09-15-2019 01:45 PM

Epoxy to kick off as in activate and harden or kick off and in soften enough to scrape off easily

View bondogaposis's profile

bondogaposis

5542 posts in 2862 days


#5 posted 09-15-2019 01:54 PM

Activate and harden.

-- Bondo Gaposis

View wildwoodbybrianjohns's profile

wildwoodbybrianjohns

323 posts in 58 days


#6 posted 09-15-2019 01:57 PM

Dont think a pressure washer is going to do much, except annoy you. If heat doesnt do anything, first thing I would do is wipe it down with acetone-ALOT. Possibly get down to something stable???

If you decide to take it all off, I think doing so with a router sled would be easier than scraping and sanding, certainly faster, cheaper(sanding belts/pads, of which you are going to need many), and a shade less messy. Maybe youll have to clean your bit in the process.

-- Wildwood by Brian Johns: It is wiser to find out, than to suppose (S. Clemens)

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CaptainKlutz

1892 posts in 2006 days


#7 posted 09-15-2019 02:30 PM

If you used the wrong ratio, you don’t have epoxy, you have uncured goo.
Cleaning goo requires lots of scraping, solvent, and elbow grease. Attempting to use power tools or sand paper just gums them up. Acetone will typically remove uncured epoxy, but MEK is better if you can find the real stuff and not substitute.

Were both pours the same brand?
If no, then entire surface coating might need to be removed?
If both epoxies formulas didn’t use the same curative, then pouring on on top of the other without waiting for 1st one to cure completely, may have interfered with both cross linking properly.
Which means you have goo that needs scraped/cleaned again.

Is it soft and tacky all the way through, or just tacky on surface?
If you attempt to use epoxy and room temp is too low, it can make surface tacky for long time. if just a little low, the curative doesn’t fully react with resin and migrates to the surface, making the surface tacky. Can clean the surface with acetone, and maybe save the piece.
If temp was way too low, the film won’t cure right. Casting epoxies also have very long, slow cure times due mass applied in single pour. As others suggested, heat to above 85F for 3-5 days before you call the epoxy worked botched.

+1 this is family site, please follow the posting rules regarding foul language.

-- I'm an engineer not a woodworker, but I can randomly find useful tools and furniture inside a pile of lumber!

View johnstoneb's profile

johnstoneb

3130 posts in 2684 days


#8 posted 09-15-2019 03:10 PM

Don’t do anything wat a couple of days. If the ratio was off it may still cure just take while longer. If surface is just tacky and you have the space mix another batch and pour on a thin coat the new coat will probably react with the older tacky surface and cure everything.

-- Bruce, Boise, ID

View CaptainKlutz's profile

CaptainKlutz

1892 posts in 2006 days


#9 posted 09-15-2019 03:57 PM



If surface is just tacky and you have the space mix another batch and pour on a thin coat the new coat will probably react with the older tacky surface and cure everything.
- johnstoneb

Respectfully, disagree with this advice.

Tacky layer of unknown chemistry may/may not be capable of reacting with a new layer of epoxy, and if it does react/cure – it will have unknown properties and bonding strength?

IMHO – This will not work in majority of instances I can think of?
- If the surface is tacky due amine bloom (from slightly low cure temp), excess amine contaminated with oxygen from air must be removed via solvent and/or sanding; or next layer will not adhere and eventually peel off with temp cycling due poor adhesion.
- If entire layer is uncured due ratio mistake, lower layer can/will steal reactive elements from new top layer, and prevent the new epoxy from curing.
- If tackiness is due overall low temp and there is no amine surface contamination; the next layer will suffer from same problem?

IMHO – OP has not shared enough information on brand(s) of epoxy, amount applied, curing temps, mix ratios, etc; for us to actually know why the surface is tacky?

One rule to remember with epoxy:
Epoxy adheres via mechanical interlocking of micro surfaces. There is no magic bonding agent in epoxy so it sticks to smooth surfaces. Try bonding epoxy to polished glass for a demonstration, and you will see that best bond strength is achieve with dry rough surfaces.

#IAMAKLUTZ, not an expert, but have bought/used epoxy in 250gal totes in commercial applications?
YMMV

-- I'm an engineer not a woodworker, but I can randomly find useful tools and furniture inside a pile of lumber!

View Rich's profile

Rich

5001 posts in 1101 days


#10 posted 09-15-2019 05:08 PM

You might want to edit your post to remove the profanity. I have no problem with it personally, but the admin will.

Regarding the epoxy, always read the mixing directions. Some are 1:1, some are 1:2. I go by weight myself. The weight ratio is either on the bottle or on the manufacturer’s web site. For example, the brand I’m using right now is 1:1 by volume but 1:0.82 by weight.

View Gene Howe's profile

Gene Howe

11853 posts in 3940 days


#11 posted 09-15-2019 05:47 PM



You might want to edit your post to remove the profanity. I have no problem with it personally, but the admin will.

Regarding the epoxy, always read the mixing directions. Some are 1:1, some are 1:2. I go by weight myself. The weight ratio is either on the bottle or on the manufacturer s web site. For example, the brand I m using right now is 1:1 by volume but 1:0.82 by weight.

- Rich


Didn’t know that. But it makes sense. How do you obtain the info about the relative weights?

-- Gene 'The true soldier fights not because he hates what is in front of him, but because he loves what is behind him.' G. K. Chesterton

View Snipes's profile

Snipes

432 posts in 2756 days


#12 posted 09-15-2019 06:03 PM

Dang, that sucks

-- if it is to be it is up to me

View Rich's profile

Rich

5001 posts in 1101 days


#13 posted 09-15-2019 06:26 PM


Didn t know that. But it makes sense. How do you obtain the info about the relative weights?

- Gene Howe

It was in the literature that it came with. To be honest, 1:1 is probably good enough for a product that’s mixed equally by volume.

View Redoak49's profile

Redoak49

4190 posts in 2500 days


#14 posted 09-15-2019 08:33 PM

I am real careful mixing epoxy and do it by weight with a digital scale. Like other have said, the weight ratio and volume ratio are different and you need to get them right for best results. If probably good enough works for you, ok.

View Rich's profile

Rich

5001 posts in 1101 days


#15 posted 09-15-2019 10:20 PM


If probably good enough works for you, ok.

- Redoak49

Perhaps if you had read the thread you’d understand the context.

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