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Possibly messed up, patchy endgrain epoxy penetration

2K views 18 replies 8 participants last post by  coalcracker 
#1 · (Edited by Moderator)
I'm a woodworking greenhorn making my first real project: a sycamore slab table from my own tree. After flattening, sanding and cleaning up the bark, I did multiple epoxy pours to fill in one large and DOZENS of smaller cracks. Following the end of those pours, probably 60% of the top surface was covered with epoxy.

Now, the problem.

As I'm sanding off the epoxy, I can see it's penetrated into the wood to an unknown depth, and made those areas singificantly darker. As I see it, I have a few options:

1. Hours upon hours of sanding to take off some unknown thickness of the top (not realistic)
2. Take it to a lumberyard and run it thorough a large planer (again, problem with how much to take off. Plus what's the fun in that?)
3. Use the router jig I made to take some off the top (not really thrilled to do this, but a realistic option)
4. Paint on a thin layer of epoxy to the raw areas of wood to help even out the grain

I'd really like to try #4 first, but don't want to waste hours of my time if it's unlikely to produce a nice result. Does anyone have opinions if this will result in a uniform finish after I apply it and sand it off?
 
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#2 · (Edited by Moderator)
Hi Greenhorn:

First tell us how you treated the slab of sycamore from your own tree. How, and how long, did you dry it? No offense, but from the questions about your problem, I am not certain that you have gotten the sycamore slab really ready for any working or finish.

My first thought was to just go ahead and coat the entire surface with the epoxy to even everything out (your #4). However, that probably will not give you the final finish look you were hoping for.

Your #2 thought conjures up visions of the guy at the lumberyard yelling "you want me to run WHAT through my expensive planer?". It could be done, and might not cause any problems, but not on my planer (fortunately mine is probably not wide enough).

Unfortunately, it is too late to offer suggestions to avoid the problem, but it is not too late to offer suggestions for the future. Without seeing the original piece it is hard to judge for certain, but could you have masked off the areas receiving the epoxy fill to avoid spreading it all over 60% of the surface? Blue painters tape (from the big box store) is great for this as well as masking areas prone to glue squeeze out, etc.

I am certain that many will suggest a card scraper, and that is sound advice. Lots of work, but it might work nicely.

https://en.wikipedia.org/wiki/Card_scraper
 
#4 · (Edited by Moderator)
Thanks Kazooman. The slab dried for over 2 years in my conditioned basement, and serial checks with a moisture meter over the last few months tell me that levels were stable and acceptable (in the 7-9% range throughout the slab).

Believe me I would have LOVED to keep that epoxy in the checks and cracks. The way it dried and shrank left dozens of small, narrow cracks (a few inches long, maybe 1/4 or 1/8" wide) scattered around much of the slab. It was near impossible to directly epoxy down into the cracks directly; I had to pour it on the surface and scrape it around to push it down.

If I could do it over, I would have probably just poured epoxy in the largest crack and left all the smaller cracks unfilled. Lesson learned!
 
#5 ·
It sounds like you got the drying part done well. You are not the "greenhorn" you profess to be!

How about a picture? That might give someone an idea of a solution.

You can get what amount to plastic syringes (without the needle, of course) and they can give you more control with stuff like epoxy or glue. Actually, you can probably find a source of actual plastic syringes and very heavy gauge needles that you can cut the sharp point off of.

Try the card scraper.
 
#6 ·
I'll try to get a picture up later, don't have a good one now.

I seem to have sanded through the surface epoxy down to the underlying wood in some spots, but it still looks much darker than the adjacent raw wood. I assume the epoxy penetrated through the end grain. Will a card scraper really help me clean this up? I feel like I would just be gouging the wood.
 
#7 · (Edited by Moderator)
One way to isolate where the epoxy goes is to build dams with silicone around where you will pour. In some cases this is better than tape, as epoxy can seep under the tape.

Problem is, the silicone can also penetrate the wood and you might not notice theres teeny spots left after sanding prep for finish until you put the finish down.

I foresee that you will be doing alot of card-scrapering, if you go that route. A really sharp paint scraper could be more effective, perhaps. Pulling is more leverage than pushing. Or a belt sander with 60 to 80 grit.

Without seeing the surface, I cant really judge, but a float pour is probably the best option, should even everything out, like Kazooman said.
 
#8 · (Edited by Moderator)
Do you intend to put a finish on the wood? If so you may find that it darkens the wood about the same as the epoxy did. Give it a try on the underside or on a scrap to see if that works.

Also you could apply an undercoat finish like clear danish oil, or boiled linseed oil which will have a darkening affect that may blend in very similar to the epoxy. Let the oil finish dry/cure for several days. Then apply a top coat.

As often stated on this web site be sure to test the affect on a scrap before applying it to the whole project.
 
#12 ·
That looks pretty bad. I think you should try your #4 remedy (Snipes agrees as well)

Then there is the "nuclear option". What does the other face of the piece look like? You probably chose the best face to be up, but the other side might be better than what you are now dealing with.
 
#13 ·
Thanks all.

I think I'd rather try my luck with a belt sander first. Some epoxy did get on the underside of the slab after a spill, so I can try sanding that first to see if it's gonna work.

If it seems like a fool's game after a while, I'll switch to a thin coat of epoxy over everything. The epoxy was a PITA and I'd rather put it completely behind me than revisit.
 
#14 · (Edited by Moderator)
Wipe the slab down with mineral spirits and see what it looks like. It won't do anything about taking the epoxy away, but will give you a good idea of what the wood will look like with finish applied.

What I have found, in my admittedly limited experience, when using epoxy to fill cracks is that the coloration of the epoxied areas is the same as what it will look like if using an oil based natural finish and you can't see the difference once the project is complete. Same as what Les B mentions. If you wipe it down with mineral spirits and the demarcation disappears, you are good to go. If not, then option #4 is viable.
 
#15 ·
The epoxy was a PITA and I d rather put it completely behind me than revisit.
- coalcracker
Exactly how I feel about epoxy now, after doing dumb stuff like what youve got here.

On a positive note, if you mix epoxy with pure talc powder until quite thick, you can then add tint to get colored filler for checks and whatnot; and I often use this filler. I use standard tint for paint, but there are various types thatll work, like RIT dye.
 
#16 · (Edited by Moderator)
If you applied ars in sspots it would look very similar. Put some ars on the backside where you have some epoxy to see what it looks like. I use epoxy often in cracks of turned items, then poly over the top. Biggest issue is with a thin topcoat that does not fill the grain, the epoxied areas are somewhat noticeable because the grain is filled. If I do a fully filled finish, wb or solvent lacquer, the epoxied areas are invisible. If you build enough film thickness with the ars the epoxy will disappear, provided everything is leveled properly. A hand plane is much better for that vs a hand held sander of any type.
 
#17 · (Edited by Moderator)
Great advice and a few things for me to try. I'll start with some mineral spirits and see what the wood looks like next to the epoxy-penetrated areas. If it disappears I may cross my fingers and move forward.

I did start out the project by flattening the slab with a router jig, so it seems quite flat to me, but I'll make sure to check for a level surface before I would apply ARS in this scenario.

Of course I could just go with the flow and call if a "rustic" finish :)
 
#18 ·
For your next experience, use a sanding sealer before applying epoxy to help minimize bleeding-in. a dam of silicone based non-hardening caulk would have been of assistance, just remember that long setting epoxies are more prone to bleed through even under caulk dams. EXPERIMENT on scrap wood of the same species. Epoxies act differently on most varieties of wood. Pore sizes in the wood will effect epoxy bleed-in potential. Don't throw your epoxy away and work from mistake to mistake, keeping notes and building a body of knowledge through experience. Don't go rushing to "you-tube" for answers before you start. Unless the film maker has a shop identical to yours with all the flaws etc and is using the same brand of epoxy on the same tree slab as yours, with all environmental variables (temp. Humidity etc.) being exactly the same the results will vary wildly ! You will be unhappy about the variance in your finished product and that of the "youtube guru". You can certainly pick up good ideas on techniques on "youtube" adventures, just don't bet the farm on expected results. Goodon'ya and best of luck.
 
#19 ·
Wanted to pass on an update.

I spent some time with a belt sander to get off all the surface epoxy and a thin layer of wood beneath. Obviously as you see in the first picture there is still a fair amount of epoxy penetration.

The second picture is after coating with mineral spirits. while the epoxy is much less visible, it's still noticeable.

So, I am going to continue for a while with a belt sander and hope I can get all the way through it. I worry even if I coat it all with epoxy I may still see some lines and blotchiness.

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