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Cured Epoxy turning white after it got wet.

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Forum topic by Blackie_ posted 12-29-2016 12:59 PM 3431 views 0 times favorited 25 replies Add to Favorites Watch
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Blackie_

4883 posts in 2633 days


12-29-2016 12:59 PM

So I had built a shelf for my newly remodeled tub to walk-in shower.

The wood I used was Nogal. I chose epoxy for the protection, the Epoxy was West System 105 resin and 206 hardener.

I constructed the shelf so that it had a slight pitch to allow water run off, I than coated it with the epoxy and allowed it to dry than installed in in the shower to be used as a shower shaving shelf. It was during the first two showers after it got wet that the epoxy starting turning white in the locations it got wet, in one particular area it turned a snow white.

Can anyone please shed some light on this?

Thanks.

-- Randy - If I'm not on LJ's then I'm making Saw Dust. Please feel free to visit my store location at http://www.facebook.com/randy.blackstock.custom.wood.designs


25 replies so far

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MrUnix

6891 posts in 2319 days


#1 posted 12-29-2016 01:15 PM

I’m guessing you meant West System and not Smith System :)

While I’ve never tried using epoxy as a finish coat, I do know that they recommend at least two coats for a barrier coat – that is, any surface that needs to be protected from moisture. Here is their recommendation:

Apply a minimum of two coats of WEST SYSTEM epoxy for an effective moisture barrier. Apply three coats if sanding is to be done. Moisture protection will increase with additional coats, up to six coats or about a 20-mil thickness. Additives or pigments should not be added to the first coat. Mixing thinners with WEST SYSTEM epoxy is not recommended.

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

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Blackie_

4883 posts in 2633 days


#2 posted 12-29-2016 01:21 PM

oop yes Brad, sorry yes I meant West Systems, can I get a free morning excuse on that? haha

Ah well that could prob be my downfall then, I didn’t read any instructions as I just assumed one coat would be enough. That’s all I ever used when I made some beer mugs awhile back.

Thanks Brad.

-- Randy - If I'm not on LJ's then I'm making Saw Dust. Please feel free to visit my store location at http://www.facebook.com/randy.blackstock.custom.wood.designs

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Roger

20938 posts in 2924 days


#3 posted 12-29-2016 01:31 PM

Maybe it just didn’t cure all the way.. ?? I really don’t know… lol

-- Roger from KY. Work/Play/Travel Safe. Keep your dust collector fed. Kentuk55@yahoo.com

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Blackie_

4883 posts in 2633 days


#4 posted 12-29-2016 01:39 PM

If it’s moisture that’s creating the white surface, I wonder if taking a heat gun to it might remove the white appearance and than go back over it with another coat or two? I might give that a try.

-- Randy - If I'm not on LJ's then I'm making Saw Dust. Please feel free to visit my store location at http://www.facebook.com/randy.blackstock.custom.wood.designs

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diverlloyd

3028 posts in 1978 days


#5 posted 12-29-2016 01:44 PM

Did you let it dry or fully cure before getting it wet?

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shipwright

8070 posts in 2918 days


#6 posted 12-29-2016 02:25 PM

Was your mix accurate. Unlike polyester, epoxies must be mixed in accurate ratios. This is often difficult when mixing small quantities. The pump type containers are made to do the measuring for you but in cold weather they lack accuracy.
You also have to mix longer than you would normally expect. Most recommend five minutes.

-- Paul M ..............the early bird may get the worm but it’s the second mouse that gets the cheese! http://thecanadianschooloffrenchmarquetry.com/

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Blackie_

4883 posts in 2633 days


#7 posted 12-29-2016 03:17 PM

Cured 48 hours.

Paul, I used small plastic mixing cups the kind that have measure lines on them but so mixture I’m unsure of.

-- Randy - If I'm not on LJ's then I'm making Saw Dust. Please feel free to visit my store location at http://www.facebook.com/randy.blackstock.custom.wood.designs

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Blackie_

4883 posts in 2633 days


#8 posted 12-29-2016 03:17 PM

Cured 48 hours.

Paul, I used small plastic mixing cups the kind that have measure lines on them but so mixture I’m unsure of.

I’m guessing all of these could be contributing factors?

-- Randy - If I'm not on LJ's then I'm making Saw Dust. Please feel free to visit my store location at http://www.facebook.com/randy.blackstock.custom.wood.designs

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shipwright

8070 posts in 2918 days


#9 posted 12-29-2016 04:12 PM

Right. Is it hard or can you mark it with a fingernail? If the mix is off it may be a little “plastic”.

-- Paul M ..............the early bird may get the worm but it’s the second mouse that gets the cheese! http://thecanadianschooloffrenchmarquetry.com/

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Blackie_

4883 posts in 2633 days


#10 posted 12-29-2016 06:19 PM

It’s a hard surface, can’t scratch with fingernail. It’s hard to tell but I could say it look a bit like plastic only you can’t scratch it.

-- Randy - If I'm not on LJ's then I'm making Saw Dust. Please feel free to visit my store location at http://www.facebook.com/randy.blackstock.custom.wood.designs

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shipwright

8070 posts in 2918 days


#11 posted 12-29-2016 07:58 PM

Then it is fully cured. Many epoxies have an “amine blush”. This might be a part of the problem. I believe the treatment is to wash with borax. You could give that a try.

-- Paul M ..............the early bird may get the worm but it’s the second mouse that gets the cheese! http://thecanadianschooloffrenchmarquetry.com/

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MrUnix

6891 posts in 2319 days


#12 posted 12-29-2016 08:09 PM

The “Amine blush” can be wiped off with a rag dampened with water… no need to go all Borax on it! IIRC, West System says to use water and a scotch brite pad… but it’s still just water. I doubt that is the problem though, as it really only effects what you want to put over the epoxy, like another coat of epoxy or something like gelcoat. In those cases, and when the epoxy is fully cured, you need to sand/scuff the surface anyway, so the next coat has something to bite into (as it will only be a mechanical bond at that point).

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

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shipwright

8070 posts in 2918 days


#13 posted 12-29-2016 09:51 PM

Results on removal of amine blush vary. I was told the borax thing by Jim Peters. He was the chemist who founded Industrial Formulators of Canada and the developer of Cold Cure, which gets my vote for about the best boat building epoxy ever.
Borax is after all just a mild abrasive, like a Scotchbrite so I guess the methods are similar.

-- Paul M ..............the early bird may get the worm but it’s the second mouse that gets the cheese! http://thecanadianschooloffrenchmarquetry.com/

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Blackie_

4883 posts in 2633 days


#14 posted 12-30-2016 01:35 PM

I’m going to take the shelf out to the workshop this week and see if I can work with it. I don’t have any Borax but will try and see what I have on hand that will clean it up so that I can put a new coat on it.

Thanks everyone.

-- Randy - If I'm not on LJ's then I'm making Saw Dust. Please feel free to visit my store location at http://www.facebook.com/randy.blackstock.custom.wood.designs

View HorizontalMike's profile

HorizontalMike

7770 posts in 3034 days


#15 posted 12-30-2016 02:09 PM

Randy,
I am wondering if using #207 Hardener might be a better choice since 206 states: ”Not intended for clear coating applications.”
https://www.jamestowndistributors.com/userportal/show_product.do?pid=2031

”...207 Special Clear Hardener was especially developed for use with West System 105 resin in coating applications where an exceptionally clear moisture-resistant natural wood finish is desired…”
https://www.jamestowndistributors.com/userportal/show_product.do?pid=2032
BTW, 207 has a 3:1 mixing ratio.

-- HorizontalMike -- "Woodpeckers understand..."

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