Epoxy

[doc henderson]

I watched the video by @Old Greenhorn this am.  Many of use are using epoxy to utilize rustic or punky wood for projects.  The products are expensive.  Some of the process we make overly complicated, and others we over simplify.  I have tutoring from many, but on this subject, I was helped a lot by @tule peak timber .  I have asked so many questions, and it is such a popular thing now with river tables and live edge stuff, I thought we could share in one spot.  I recently did some ERC tables for Dallas and a friend of his (retired firefighter).  any friend of Dallas is a friend of mine.  I did thin viscosity first to stablize.  I dried in the warmer for a day.  I then applies spar urethan e over it.  I kept getting what looked like dust nubs.  Dallas was happy but I was not.  maybe could have buffed?  kept re-sanding smooth and got the same result.  tried tack rag, wiped with mineral spirits.  blew off with air.  Kept getting the same results.  any thoughts or suggestions.  I think you can thin with acetone, so tried wiping with it once.  same problem.

this thread it meant for all with questions, thus the simple title.  one place to go for questions, projects and suggestions regarding Epoxy!



 

 

[Old Greenhorn]

Doc, I gotta ask a basic one first: Why the urethane on top of epoxy? Seems to me that epoxy is pretty bullet proof, but I have not really observed it over the long haul yet. The bar I am doing now I had planned on stopping with the epoxy finish. Maybe I should re-think?
 As for your issue, I have had very good luck with 20% mineral spirits in the urethane for thin final coats. Keeping the area dust free is also critical and the only way I can manage that is to shut off all fans anywhere in the building and stay out of the shop. :D
 Good thread.

[reride82]

Doc,

Like Tom said you need a dust free environment. A dedicated finishing area is best, but if not build yourself a temporary "booth" of sorts out of plastic that you can keep dust free. When I was painting cars we would construct a paint booth out of a wood frame and cover in plastic with fans and filters to keep the air clean. We would use box fans and the finest furnace filters you can find. Once it is built, clean thoroughly to remove dust then wet down the walls and floor to mitigate any dust you could have stirred up. During painting or finishing keep the floor wet to avoid kicking up any residual dust. This is the method I've always used to get a dust free finish.

Levi

[doc henderson]

thanks.  I have a small paint booth and it made no difference.  I should clarify, "they looked like dust nibs", but they were not.  they popped up seconds after the finish was applied.  bought new finish, still happened, so not a bad batch.  occurred too fast for actual dust nibs.  I worried something was still off gassing.  let them sit for days, same thing.  this is just one example of a question, and not meant to define the whole thread.  thanks reride.

[doc henderson]

My understanding is that epoxy is not UV protected, so this was to try to preserve the color of the ERC.  no windows in Dallas's shop.  I brushed a few coats and it was thicker and helped.  I try to sand the epoxy almost back down to wood and not the think counter top 1/4 inch thick.  recommended by WOC.

[Old Greenhorn]

Well, if not dust Doc, perhaps it is debris on the surface that you didn't see while applying the finish? I am pretty sure it is your habit, as mine, to wipe the entire thing down with mineral spirits and allow to dry before applying the finish, correct? I have found I need to give it a 'hand wipe test' after the MS dries and sometimes I find tiny particles I somehow missed. So I have to do it again, and check it again. If this may be the case, these missed particles (I am postulating here) would float to the surface fairly soon and pop up as you are seeing. It's just a theory from 1800 miles away, but it has happened to me. In that case, you either pick them out quick and smooth with a torch, or let dry and start over. All it takes is a few in one tight corner that the brush disturbs, then spreads around to mess things up. They have to come from somewhere, if not just air or outgassing.
 Anyway, it's just a theory to help think it through.

[doc henderson]

Is there an easier way to mix epoxy?  I have used a drill and got translucent stuff in the bottom of those table due to small bubbles.  How about a slow speed magnetic lab stirrer?  prob. would not clear the viscous stuff of the sides and end up with some not catalyzed sticky stuff.  @tule peak timber you buy it by the barrel if I recall.  is it all hand stirred  slow drill?

 

 

 

 

 



also you mentioned adding sawdust to it to more quickly fill edge cracks on live edge that had dried as a log and had these pics.  that worked great.

[tule peak timber]

Hand stir only and with bartop coating the double bucket method. No matter how you try it is really difficult to get it completely mixed, which is why after vigorous hand mixing we will pour out the bucketful as completely as possible, but not let it drain upside down or scrape the sides to get every last little bit. Epoxy is funny stuff; it needs the right number of molecules to react with itself and if it has a few too many of this or too few of that, it doesn't set completely. Plenty of mistakes on my part to back up this statement! 

[firefighter ontheside]

Did you use a torch to burst any bubbles which rise from the bottom?  Gotta do that for quite a while while the resin is starting to cure.  Once the resin gets thick enough, bubbles will not rise any longer.  Also be careful not to burn the resin.  

[tule peak timber]

I use a heat gun. I try to do several thinner seal coats to prevent any bubbles the best I am able to. Chasing deep errant bubbles is VERY time consuming $$$$.

[Don P]

This happened with the urethane coat rather than the epoxy, is that right? If so, you did wipe down with spirits, but where you by any chance using a stearate sandpaper... is it mini fisheye?

[doc henderson]

it was raised.  it deformed the skin and after dry, could be felt to my hand.  it sanded like back like glass easily, but popped up right after spraying.  bushing was better but not perfect.  I wiped with mineral spirits and once with acetone.  wiped with tack cloth and blown off with an air hose.  when I have had dust nubs, after sanding the next coat was great.  on rustic stuff, I often brush first coats till filled, sand and spray final coats.  I will be tempted to wait months, and then sand it down to near wood and try again.

[peakbagger]

I will give this another try as the last attempt seemed to lock up before the reply posted.

Some things I learned dealing with industrial coatings over the years and about 10 years of strip building boats. Any coating including epoxy can get bubbles in it from applying it with the wrong temperature profile. Ideally when any coating is applied, it should be applied warm and then the temperature should drop slowly. This keeps gas bubbles in the surface and in solution from expanding. Most folks tend to go directly opposite especially with epoxy to get extended cure time, by starting cold and then warming the area up post application. This causes gas bubbles to come out of solution appear and reduces the likelihood of them collapsing. When wetting out strip kayaks, fiberglass is applied to the hull first and it has to be wet down for the epoxy to make it "disappear" No matter how clear the epoxy is mixed, air bubbles will form while applying and the and generally the temp sloping down to the point where the epoxy sets will make then go way. When we applied barrier coatings over rough concrete, we would see bubbles appear on the surface if the product was applied as the temps rose, if we waited until the later afternoon as the temps dropped those bubbles would reduce in size and bond back in the concrete voids as the temps dropped. Once cured they would stick and then we usually applied a second coat the next day.

While I am at it, be aware of amine blush. It forms on the surface of the cured epoxy and is formulation dependent, industrial non optical epoxy seems to have worst blush. It needs to be washed or sanded off prior to applying a new coat or it can mess with clarity of the surface.

Be aware, spar varnish varies considerably in UV screening. My first canoe was coated with run of the mill spar varnish and within a few years the epoxy clouded. Subsequent kayaks had far more surface detail and I did not want them to cloud. I was on a kayak builders forum whose founder had one of his boats go in the permanent collection of the New York museum of modern art. He recomended regular Epifan's initially. I think later on after I stopped building them, I think the go to was two part Epifan's polyurethane spar varnish product that was superior. Regular varnish is fairly soft while the two part poly ends up much harder. The trade off is these two part products can be very potent when mixed and applied, it requires a special cartridge type respirator with proper cartridge. The 2 part poly is expensive and require Hazmat to ship but worth it. I buy mine at Hamiltons Marine stores along the Maine coast when they have a sale.

[tule peak timber]

  8) ;D

[Brad_bb]

I've gone through 4 or 5 gallons of West systems epoxy on filling boards, checks, knots, etc over the last 8 years.  I've also used one kit of the smiths water thin epoxy for stregthening wood.  I've also gone through one Ecopoxy kit for deeper fills.  I definitely plan to do more in the future.  I am planner a few epoxy tables - a walnut burl cookie table, and a couple walnut river tables.  For my next deep pour kit I'm planning to try the liquid epoxy that cam at Blacktail uses.  All just stuff for myself.  

[peakbagger]

My Unimog cargo body came with a plywood deck about 1-1/4" thick that looks like MDO plywood on steroids. It is about double the size of a normal pickup truck bed. I swapped the cargo body for an ambulance body that the truck came with as it was more useful. The cargo body had been outside for an unknown period of years and the upper layers of plywood were "tender" in spots. I had a gallon of West system epoxy and some graphite additive used for coating boat hulls. I cleaned up the plywood well and used a plastic scraper to move it around. It sunk down into that plywood and sealed up all the deterioration. When I drilled down into the wood to install some brackets, I could see that it had penetrated in at least the third of the way. Once it set up, I scuffed it up and put a top coat of a polyurethane deck liner. Its holding up like a champ, if I drag something across it, it might scrape a bit of the bed liner off, but graphite infused epoxy just takes it. Its been 3 years including 3 winters outdoors and is holding up great. The frame is steel with the plywood set into it. I used a Sikaflex sealant to fill the gaps. 

[doc henderson]

what are you guys using to thin epoxy?  does it matter on the brand or content of the epoxy?  @tule peak timber is there an additive to help make it uv protected?  I assume not or it would be advertised and add a hundred bucks to the cost!     do you all do an overcoat to protect it from UV.

[doc henderson]

looks like the best way is heat.  whether you heat the epoxy, or the wood.  In the first instance, it may catalyze the reaction, and you may see smoke.  that is too much.  I used some in a pour over pinecone seeds as a filler, but it was deeper than recommended, and it had gray smoke rolling out.  you can heat the wood, and then the epoxy thins as it is heated by the wood.  You can heat mixed epoxy, but it is curing as you heat it.  you can heat each component separately, but still after mixing, it will cure faster.  

It is mentioned you can use denatured alcohol, acetone, or lacquer thinner, in a ration of 10 to 1.  I read all this on the internet so it must be true!     so we ask our resident WOC.  sounds like the additive methods can degrade the strength of the product.  buying the low viscosity penetrating sounds like the best,  but it is expensive.  and has gone up!

[tule peak timber]

There are only 2 epoxy formulas that you can thin. One is from Smiths, the other is from Jamestown Distributors (Total Boat). I suspect Smith is supplying the latter. He is an interesting guy to talk to. 

Most epoxies you can get by with a very small percentage (give or take 5%) of thinner additive but if you go beyond that the epoxy will not set right. There has been some talk lately on the threads about putting on thin layers of epoxy and here we use soft spatulas to put on paper thin layers, sanding in between for good mechanical adhesion. A lot of epoxies, if they are green and not fully set, can be layered  with both chemical and mechanical adhesion. We prefer to wait, sand and re-coat. 

[scsmith42]

I've been using RTG and Total Boat's "Rot Fix" type of epoxy for stabilizing punky areas in wood.  It has a viscosity or around 5 wt oil (little thicker than water) and is readily absorbed by the spalted wood.  It works great.

[Crusarius]

great thread. definitely going to subscribe to this. Maybe one day I will even play with epoxy.

[peakbagger]

I was at Hamiltons Marine 20% off sale and picked up a gallon of West System

[Old Greenhorn]

Obviously I've been reading along since the onset, but my input has been minimal because I am no expert with this epoxy stuff, it's maddening and frustrating. In fact I called Doc earlier this week just to discuss and vent some frustrations. It's tough stuff to work with. Mostly this is because we all hope to get optically flat, clear, clean reflective surfaces. The optics are tough, very tough. I know a lot of folks use very expensive material to work with, some of these penetrating epoxies are crazy expensive. I don't have those deep pockets. I have been trying the epoxies I get on Ebay, got a half gallon kit from Brooklyn a year ago that was pretty good, then got a gallon kit for CA, but I think it may have come from China, not bad but if you weren't really attentive and careful, it could result in cloudy fill. I use the stuff I get from HD for top coats, very clear and clean. I also just bought a gallon kit from a company in TX called Lone Star epoxy and that material calls for a 1:1 mix by volume (they are VERY clear on that) and only says mixing time is 3-6 minutes, which is remarkably short to my experience. Son of a gun it mixes up clear, goes on easy and is hard the next morning.
 I used it today for a fill pour (taking up space) and it's working well. Very clear, which is what I want. I don't yet know how it will sand out. Time will tell.
 Doing a flat pour is easy... until you get to the edges. I have been working on how to deal with edges. If you watch the youtube epoxy 'experts', many of them make complicated frames and damming systems so they can just dump a whole lot of epoxy in ($$$$) and the frame forms the final perimeter shape. I won't do that. so I have to spend a lot of time re-shaping the edges to match the natural contours of the wood. That's kind of tricky, but I am getting better at it. Getting the final shine is the tough part.
 As Doc mentioned I am working on a series of videos on my current project (a bar) and have a playlist setup on YT. I am no expert by any means, and these videos are as much to show my concerns and challenges, as they are to show my process. As an exampkle, here is today's Episode (12), but if you have an interest, just look for the playlist and see how much you can tolerate. I am not pushing my YT channel, I get no money from it and I surly am not tooting my own, or anyone else's horn.

The Bar Episode 12 - YouTube

 Epoxy is tough to do right.

[doc henderson]

very nice Tom!

[Machinebuilder]

I didn't find it boring.

I have not tried anything like this. I like the different layers and coloring.

I may have to try this sometime in the future.