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Thread: Finishing large live edge slabs

  1. #1

    Finishing large live edge slabs

    I've been asked by son-in-law to finish large (roughly 11' x 3') live edge slabs for bar and counter tops.
    Slabs (2) are 2 1/8 inch thick or so marked. They are kiln dried to 10%, black walnut, about 85% heart wood, the sapwood
    is a good contrast. The bar slab will sit on 2x constructed frame with some type of beadboard facing. The counter top will sit on
    custom build base cabinets. All painted white.

    Two parts to the project, 1)filling knot holes (some through and some not), and 2)the actual finishing.

    I've never handled anything of this scope before and looking for guidance on finishes, level of sanding required, and epoxy filling of through and some not so through knot holes. They want a satin like finish, and don't like the typical bar top epoxy look. I'm thinking GF armor seal or endurovar.

  2. #2
    the arm r seal is generally perceived as more durable than endurovar. I would tint slow setting epoxy black and fill the voids with that. This will obscure any air bubbles that might otherwise dry in large voids.

  3. #3
    When I finished live edge slabs for a kitchen island, I used Minwax oil-based floor poly. We've been fairly careful about not marring up the top and it's held up pretty well. I put Minwax WB poly on a wood bar top and is hasn't held up as well. As far as appearance, the oil-based finish is far better.

    I've used a lot of Endurovar but wouldn't recommend it for tops.
    “Travel is fatal to prejudice, bigotry, and narrow-mindedness..." - Mark Twain

  4. #4
    Prashun, thanks for responding, a question, what would you use to tint the slow setting epoxy? And a second, for filling a 2 inch through hole (was a knot once) would it be best to pour several levels of epoxy of go for all at once?

  5. #5
    Join Date
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    A problem with filling large voids with epoxy is that it self-heats as it cures. It can easily get to the point that it is smoking. Use a sloow catalyst. Smaller holes aren’t a problem.

  6. #6
    i Use transtint. 2” is large for me. What I do in this case is use a bulk filler like sawdust to give body to the epoxy. I then do one layer below the surface. After that has hardened overnight, I use unbulked epoxy as the top layer.

    Tinting makes it opaque. You only need a drop or two in that much epoxy.

  7. #7
    Join Date
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    This is an area where I have a fair amount of expertise. Although there are a lot of epoxy choices, West System with the slow setting 206 hardener is what I prefer when I’m adding a tint to the mix, or 207 hardener if I’m leaving it clear.

    For tinting, I use automotive paint (typically black).

    If possible, tape the “show side” of the slab and pour the epoxy from the back in 1/4” thick increments. By doing this the air bubbles will rise away from the show side, leaving you with a smooth surface after planing.

    If you are not able to fill from the back side, then fill from the front - also in 1/4” increments. Use either a heat gun or hair dryer to thin the curing epoxy so the air bubbles are released (for about 5 - 10 minutes after pouring).

    My preferred finish for a table or bar top that will have drinks, hot plates, etc on it is post catalyzed conversion varnish. Most commercial restaraunt furniture is finished with this product and it is extremely durable and chemical resistant, but w/o the “plastic look” of epoxy.

    Although I like oil based finishes on a lot of pieces, IMO they tend to turn black walnut too dark and you lose some of the character of the wood.

    The most important thing to remember when finishing wide slabs is to apply the same number of coats of the same finish to all sides of the slab. I cannot stress this enough - put the same quantity of finish on the bottom side of the slab that you put on the top side, or else you may experience cupping over time.

    Best of success to you with your project.

    Scott

  8. #8
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    Julie - what do you not like about Endurovar for tops?

  9. #9
    First, thanks to all for responding. We got delivery of slabs on Thursday last and i was able to Sand and tape the show side Friday. Now time to flip and work on the underside (sanding, bark removal, etc). I'm unsure how to sand the live edge itself, any advice would be appreciated.
    The soon to be owners have looked over youtube extensively and found John Malecki's work which they like. He stops sanding at 120 and finishes wit Rubio Monocoat clear (one coat only). I'm interested in this approach as I'm not is a position to spray in the building where we have the slabs.
    Any comments or experience with Rubio products?

  10. #10
    I just sanded my live edge walnut slab using an angle grinder with holey galahad wheel by king arthur tools. Knocked the bark off with a hammer and chopped the stubborn stuff off with a chisel and cleaned it up with the grinder and then sandpaper.

  11. #11
    I use a wire brush to remove bark and grit from the edges and to burnish it without removing too much texture and or color. You have to work it a little at a time, step back and stop when you think you have it.

  12. #12
    Join Date
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    Quote Originally Posted by Bill Dempsey View Post
    First, thanks to all for responding. We got delivery of slabs on Thursday last and i was able to Sand and tape the show side Friday. Now time to flip and work on the underside (sanding, bark removal, etc). I'm unsure how to sand the live edge itself, any advice would be appreciated.
    The soon to be owners have looked over youtube extensively and found John Malecki's work which they like. He stops sanding at 120 and finishes wit Rubio Monocoat clear (one coat only). I'm interested in this approach as I'm not is a position to spray in the building where we have the slabs.
    Any comments or experience with Rubio products?
    I start with a cup brush on a 4-1/2” grinder, and then usually finish up with a Festool Rotax 150.

    Re the Rubio, you might want to try a sample first because it will darken up the BW quite a bit.

  13. #13
    10% MC and I'd say your slabs aren't ready for finishing. I'd hold out for 6% and do the work to get them there. Them machine and finish...

  14. #14
    "10% MC and I'd say your slabs aren't ready for finishing."

    I think this is regionally dependent. I also think this is thickness and species, and specific-piece dependent.

  15. #15
    Join Date
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    I agree with Prashun. Getting that low is nearly impossible in many areas because of ambient humidity, especially in thicker material. Even KD "gains" MC in many places...
    --

    The most expensive tool is the one you buy "cheaply" and often...

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