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Walnut Slab Coffee Table #2: Finishing and the final result

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Blog entry by Lumber2Sawdust posted 03-25-2013 03:24 AM 2993 reads 1 time favorited 3 comments Add to Favorites Watch
« Part 1: Flattening slab with router sled Part 2 of Walnut Slab Coffee Table series no next part

I started this blog with a post about flattening the odd-shaped slab of walnut over a year ago. A lumberjock recently requested that I follow up on that post as I had intended to. I don’t have as many photos of the rest of the process but will describe what I can.

The router sled was awesome for making the slab flat and it was smooth enough that I could spend some time with hand planes and a card scraper to get it smooth without too much difficulty. It was still challenging because of all of the figure in the slab.

Before I could smooth the slab completely I had some other work to do: epoxy. The mill started cutting a slice from this slab and hit a piece of metal so they backed out the blade and didn’t finish the cut. You can see a dark streak in the surface, and see where the hole is. I hit that metal with the router! I never got the metal out. I just used a nail set to force it below the surface then filled the void. That was from the cut end of the slab. I decided I wanted to stabilize the slab by filling the slice by gluing in some strips of walnut were I could, then fill the rest with epoxy. There were also several voids in the crotch section of the slab on the top that I wanted to fill. I bought some epoxy from Woodcraft and some black dye for it, too.

That slice (from a band mill) swallowed up a tremendous amount of epoxy! It took me at least 5 sessions of adding more epoxy to the openings. I had to use (many) layers of masking tape to resist the hydraulic pressure of the epoxy on the edges so it wouldn’t just flow out the sides. In the end, I’m happy with the result, and you don’t even notice it in the finished piece. It would have been wise to use an epoxy that set faster. I just didn’t know which one to use.

When filling the voids in the surface I had a lot of troubles with air bubbles in the epoxy, too. I would use a plastic cup to mix the epoxy and then pour it into the voids. I have read advice that you should avoid over-agitating the epoxy when mixing it so you don’t trap too much air. I guess I’m not able to stir it thoroughly without whipping in a lot of air. The epoxy would take its time descending into the bottom of the voids. Some must have been pretty deep. It seemed that the epoxy would drain into the void for a while and then stop, as if it were full. Then just before it set, it would flow some more and I would still have a void to fill again. I used a lot of masking tape to prevent the epoxy from going too far, or possibly staining the surrounding surface. Here is a shot of the top while I was in the process of filling voids:

After the epoxy set, I would use a block plane and card scraper to remove the excess. That is when I would find that the bubbles in the epoxy were now visible at the surface level, so it was time to mix another batch of epoxy and start the process again. I would love to find a better way to do the epoxy so that it doesn’t take quite as long but the result was worth the hassle. After all of the filling was done, this is when it was ready to finish:

The figure in this crotch slab is amazing so I really wanted a finish that would highlight the beauty of the piece. I chose Watch Danish Oil. In spite of this being walnut, I didn’t use the walnut-colored oil, just the clear version. I followed (roughly) the steps outlined in this web site. Basically, the process is to apply the danish oil using sandpaper. I believe I started with 400 grit. The slab was already pretty smooth from planing and scraping it first. The 400 grit might have been more than I needed. I probably could have started at 800. I spent a lot of time on that first application though. The walnut absorbed a lot of oil on the first few coats, especially in the sap wood.

The process has you just stepping up to higher and higher grits. You are polishing the surface by wet sanding with the danish oil. After the first application, it starts going much faster. I’m not sure if that means I was less uptight about it, or if things start to progress more easily. It can be hard to really see any defects while the finish is wet, so I kept working the surface, probably well beyond what I needed to because it seemed easier than having to deal with finding an imperfection later.

This is the bottom side of the slab. I didn’t smooth it out to the same degree as the top, so you can see some of the imperfections. I flooded the area with danish oil to see how it would look:

The instructions I linked to say to you can stop at 1000 grit. It depends on how fine you want the finish to be. I kept looking from a low angle across the surface of the slab and could see scratches. They kept getting smaller and smaller after every grit, but I could see them. I don’t remember if I stopped at 1500, or went to 2000. In the end, you can drive yourself mad trying to get it that smooth. The table has been in our living room for a year now and nobody has put their eye down at the level of the table and looked for scratches from the sanding! In fact, I don’t notice them in daily life. It looks just fine. I wouldn’t go any higher than 1500. Once all of the polishing was done:

My wife was adamant that she wanted a metal base for this piece. I would have preferred to build something from wood (I’m a woodworker after all!) probably inspired by Nakashima, but we went for the metal base. We spent a lot of time looking at various catalogs to find styles we liked, and possibly to buy something and just replace the top with this slab, if the price was right. We never found the right fit from anything commercial.

My wife found a local business that mostly builds custom signs. The guy has a forge and the ability to work a lot of metal for custom hangers for signs and other cool stuff. We took the slab to his office on snowy Saturday morning and we spent quite a bit of time with him deciding what we liked, and sketching out some things I had envisioned. We settled on a 4-legged design with each leg arched toward the center. The opposing legs were joined by a thinner arched piece to provide some room beneath the table. (I’m tall, and hate sitting somewhere when I can’t stretch my legs). It took him a couple of weeks to get the base done but it was well worth it. The base has a small metal circle on the top of each leg with holes to screw it to the top. Actually I never added screws. It is just gravity and inertia holding it in place! I may screw it down eventually though. Here is a shot of the final piece:

I can say that the base is exactly what my wife and I asked for but after getting it all together, I left me feelling … unsatisfied. I think the scale of the base and the slab don’t work together. If I ever complete all the other projects on my list, I might build a different top to use with this base and build a Nakashima-inspired base for this slab. I think it will just look better.

That said, when a friend saw it, she sat down on the couch in front of it and said “I’ve been trying to find a coffee table I like for 5 years. This is what I want.” I’ve gotten a lot of compliments about it, but that one takes the prize. I have a customer wanting a coffee table if I ever have time to build things for others.

I really like the look of the danish oil finish. You have probably already heard that danish oil isn’t great for protecting wood, especially for high-use pieces. I was willing to take the chance. Since we don’t have kids, the coffee table won’t get a lot of abuse. I did sit a coffee cup on it and there is a slight ring as a result. Use a coaster! Putting a more durable finish over the top might be wise, but I’m going to leave it for now. If you anticipate more use, I suggest a different finish, or a topcoat over the danish oil.

I’ve already used the router sled to build a desk from 2 bookmatched pieces of walnut, too. I think that one came out even better than this table did. I encourage you to take the time to build a sled like this. I really enjoy working with slabs.

Thanks for reading.



3 comments so far

View BTimmons's profile

BTimmons

2127 posts in 1143 days


#1 posted 03-25-2013 03:32 AM

That came out looking good. I agree that a wooden base would be better, but sometimes we have the choice of winning an argument with our wives, versus being happy.

-- Brian Timmons - http://www.BigTWoodworks.com

View Cosmicsniper's profile

Cosmicsniper

2199 posts in 1817 days


#2 posted 03-25-2013 01:15 PM

It’s gorgeous, but I think you need a top coat. I recommend a water-borne poly like GF Endurovar.

-- jay, www.allaboutastro.com

View Randy_ATX's profile

Randy_ATX

676 posts in 1100 days


#3 posted 01-07-2014 12:33 AM

Searching LJ for slab finishing – thanks for posting the details.

-- Randy -- Austin, TX by way of Northwest (Woodville), OH

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