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Tips and tricks with epoxy finishes...

Started by Ljohnsaw, June 22, 2020, 06:10:59 PM

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Ljohnsaw

I did my first real epoxy work on some cedar and ran into a few problems.  I know that @tule peak timber would have a whole slew of tips to educate me but I figure a consolidated list would help a lot of people here.  Here is what I know -

1) Mix well
2) Plug any cracks from the bottom side that your are trying to fill
3) Use a propane torch to pop the bubbles by quickly passing it over the surface - don't hesitate or you will bubble and burn the epoxy... ::)

What I need help on is what I call cratering.  The wet epoxy pulls away from some areas (usually after the first layer) like there is oil on it.  If I poke, or stipple, the brush in the area and work it, it will lessen the issue somewhat.  What would be a good thing to wipe the surface with to prevent it from happening?  I have paint thinner, turpentine, denatured alcohol and lacquer thinner. Then some more dangerous stuff like gasoline and white gas (Coleman fuel).  I am hesitant to use lacquer thinner on it.

Also, I'm using Total Boat slow set (left over from another project).  It does set real slow - like 2 hours slow!  I'm working in my basement workshop.  Cool (75-80°) but dry.  Once hard, it has a oily or waxy feel to it.  Probably what causes the above issue.  Or, maybe something is wrong with the epoxy or my mixing?

On my final coat, a bunch of little black commas (,) showed up - like a dozen or so.  Turned out to be some little tiny gnats.  Didn't get any before, stupid bugs. >:(
John Sawicky

Just North-East of Sacramento...

SkyTrak 9038, Ford 545D FEL, Davis Little Monster backhoe, Case 16+4 Trencher, Home Built 42" capacity/36" cut Bandmill up to 54' long - using it all to build a timber frame cabin.

Crusarius

I can't help any but very interested in this topic. 

Did you ever check the moisture content before you started? Isn't cedar known to have oils in it? 

alan gage

I've epoxied a lot of cedar over the years building canoes. Never had an issue with fisheyes. How was the wood prepped before hand and what other chemicals had come into contact with it?

The oily/waxy feel is probably amine blush. Remove it with soap and water.

Edit:
Quote from: ljohnsaw on June 22, 2020, 06:10:59 PMThe wet epoxy pulls away from some areas (usually after the first layer) like there is oil on it.


On the first read through I missed that the fisheyes occurred after the initial coating of epoxy. Could be from the amine blush.

Alan
Timberking B-16, a few chainsaws from small to large, and a Bobcat 873 Skidloader.

beav

+1 on the amine blush.
Wood will outgass and cause bubbles or stippling if its temperature is rising as the epoxy setting up. You can minimize this by allowing it to cool just a bit during setup.
Be careful not to breathe uncured epoxy. It is highly carcinogenic. Sand it after it fully cures. (And after wiping off the amine blush with a wet rag)
Most epoxys are poor u/v amd need protection from the sun
I've built boats and iceboats for years using veneers from my mill and gallons and gallons of west epoxy.

samandothers

I had to look up amine blushing.   

I have only epoxied one piece to help level a cupped top on an old washstand.  I did not have this issue with Total Boat epoxy I used.  My final thickness was about a 1/4"after several pours.  I did have the wood off gassing or bubbles and the torch did help that.  I had thought about using a heat gun to eliminate the flame portion of the program, but thought it would just blow unwanted items into the finish.  I did have two gnats on my final coat.  I dug those out and put a couple of coats of Waterlox over the top to drop the gloss down.  That may have been a mistake as the finished piece is not as smooth, little specs of dust or something making the surface finish not that great.  Not my best work but it will be functional.

Poquo

I clean all dust off first , then wipe surface with a micro fiber cloth , then use Denatured alcohol to wipe down the wood with , then I wait about an hour before putting epoxy on it . The first coat of epoxy I use a stiff foam brush to paint a thin coat on to seal the surface .
2015 Woodmizer LT40HD26

Brad_bb

I've never epoxied Cedar, only walnut and Ash. I've used West systems.  Never had any of the issues you describe. Never "pulls away".  West systems I used for small epoxy pours/repairs.  You can't pour it thick- about 1/8 at a time, maybe  1/4 if it's a small crack area.  Point is not to have too much volume that can heat up.

For deeper pours, there are several good brands on the market that I haven't tried yet.  They are meant to pour deep and cure slow so they don't heat up and consequently, you don't need to stand there and pop bubbles.  They pop themselves because it takes so long before it sets up.  You definitely don't want to epoxy where you'll get bugs in it, though I have been known to encapsulate dead and dried Cicadias and other large beetles in epoxy fills.
Anything someone can design, I can sure figure out how to fix!
If I say it\\\\\\\'s going to take so long, multiply that by at least 3!

firefighter ontheside

I didn't see any mention of a seal coat done several hours before the pour.  I think this should be included in your process.  Will help to reduce bubbles.
Woodmizer LT15
Kubota Grand L4200
Stihl 025, MS261 and MS362
2017 F350 Diesel 4WD
Kawasaki Mule 4010
1998 Dodge 3500 Flatbed

Ljohnsaw

Thanks for all the replies.  I've been up the hill cutting wood for my cabin.  The cedar was very dry - like 2 or 3 years.  It is about 3" thick.  No prep work other than sanding it smooth and wiping it down.  the fisheye only happened after the first coat.  I'll try washing it down with soap and water? the next time.  Bubbles are not a problem.  Just a few from brushing.
John Sawicky

Just North-East of Sacramento...

SkyTrak 9038, Ford 545D FEL, Davis Little Monster backhoe, Case 16+4 Trencher, Home Built 42" capacity/36" cut Bandmill up to 54' long - using it all to build a timber frame cabin.

Don P

Only thought is some sandpapers have stearates on them to help prevent clogging, usually but not always the white paper. It can cause finishing problems.

Ljohnsaw

Quote from: Don P on June 26, 2020, 06:43:31 AM
Only thought is some sandpapers have stearates on them to help prevent clogging, usually but not always the white paper. It can cause finishing problems.
Interesting.  So denatured alcohol to clean that off?
John Sawicky

Just North-East of Sacramento...

SkyTrak 9038, Ford 545D FEL, Davis Little Monster backhoe, Case 16+4 Trencher, Home Built 42" capacity/36" cut Bandmill up to 54' long - using it all to build a timber frame cabin.

Don P

Not a clue, you'll have to google, I've just tried to avoid knowingly buying it. The caution I remember was for polyurethane finishes fish eying, I'm not sure of its reaction with epoxy, just popped into my head after seeing that you had just sanded.

Ljohnsaw

So I installed the mantle.  Really poor pictures but my friend is really happy with it.  I now know that I will never use this for a table.  Not a very durable finish.  But works for this:


Funky angled wall, but a good fit.  Nice wormy live edge.

 
John Sawicky

Just North-East of Sacramento...

SkyTrak 9038, Ford 545D FEL, Davis Little Monster backhoe, Case 16+4 Trencher, Home Built 42" capacity/36" cut Bandmill up to 54' long - using it all to build a timber frame cabin.

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