Black walnut river table help

[burtle]

So I'm working on my very first black walnut river table.


I'm seeking suggestions on how to fix/fill the imperfections as you can see in the pictures. The knots and cracks.

I know they aren't high grade walnut boards, but they were free.

At the end of the day the table will be 7' long and 46" wide. 5" will be epoxy (blue of course)

To finish it off I plan to do several clear flood coats.

Any information would be greatly appreciated! The first step is to fix the imperfections. What do you guys suggest I put the table on for the pour? MDF board? And then line the MDF board in tuck tape?

I don't want to pour it on the sheeting that its on. That's a work bench I built. It now has legs and is about 4' off the ground. It will be a wood working bench from here on out.

 

 

 

[Ianab]

For the knot holes / cracks, tape up the reverse of the board, and maybe the sides if you think the resin can ooze out there. Then put down some paper underneath, in case it gets around your masking tape. 

Then make up a small batch of resin, and start pouring it into the holes. Don't worry if you get a bit left on top, that can be sanded off later. Pour some more in if there is still a hole. Chances are it will take a couple of pours to get the holes filled, it always seems to soak in a little more once you walk away. 

Then once that's cured, sand any residue off to the level of the wood, and carry on with your build. You will probably find you have tape and paper glued to the back of the board, scrape and sand that off. 

[WDH]

You can also mix walnut sanding dust and wood glue into a biscuit-dough like consistency and fill them with that.  I have not tried it yet, but a furniture maker told me that you can also mix the sanding dust with clear epoxy and use that to fill holes and cracks.

[thecfarm]

Whatever you do,keep us posted. Not that I can build something. Sure would not be walnut either.
My wood working skills stop when the tree hits the ground.  :D

[btulloh]

Not sure the responses address the question.  I think the OP's going to epoxy that open space in the middle.  That's outside my expertise.  I can fill a knothole with epoxy, but I've never tried to fill the Mississippi River.

Watching . . . . .  .  .  . 

[Ianab]

Well the first part of the question was about the knot holes. I've filled my share of those  :D.

But I haven't done a whole river either, so I'm not sure exactly how I'd attack that. 

[low_48]

5" is very wide for the resin! Have you priced it? Have you poured anything before? I'd say you need something to hold the wood together that has more strength than the resin. I've not poured anything, but read about all the trials and tribulations from the guys on a pen turning site. They use a urethane resin and it is highly intolerant to moisture in the wood. Lots of bubbles and almost foam when it is poured on wood with any moisture at all. Those guys now bake the wood in a toaster oven before casting. For repairing holes in my turnings, I mix epoxy and used dried coffee grounds. It has a more organic look that epoxy with dye. The dyed epoxy looks too much like plastic to me.

[Ianab]

Done properly the epoxy is likely stronger than the wood, and I've seen people doing those wide pours, sometimes they seem to have more plastic than wood (not my scene at all). But you are going to need a bucket load of epoxy there for sure. One thing about large pours seems to be the heat it generates, and that likely makes any moisture even more of a problem, and some resins will actually "cook" and go cloudy (smokey / foamy?) May need to do thinner layers over several days?

My suggestion would be to try some smaller experiment pours, maybe in conjunction with filling the knot holes in those boards. A top for a little side table or similar? Make sure your technique is good before you blow a whole bucket of resin. 

For larger knotholes I've also filled them with "Bondo", but below the surface level. Then actually spray painted the bondo black. Sanded the overspray off the top, and then filled the depression with epoxy. If you want to embed something in the top, this works good too. The coin etc is then sitting on a black layer 1/4" below the surface. 

[Crusarius]

Wax paper makes a nice barrier to prevent the epoxy from sticking to the work table. If I was going to do what you are attempting I would cut live edges off of other boards and put them into the gap to make it look like a river valley and then it will use quite a bit less epoxy.

As other ppl have said epoxy gets hot as it cures. To thick of a pour will cause it to cook and cloud. Be careful with that.

Really looking forward to seeing progress on this. I have thought about doing it myself. Just haven't jumped yet

[low_48]

The epoxy may be stronger than the wood, but it's the bonding to the wood that would make me nervous. Polyester resin shrinks when curing. Every river table I've seen has natural edges in the resin, providing more surface area. 

[burtle]

Thanks everyone!

I ordered a filler for the knots and small cracks.


Once I get those taken care of I'm going to flip the boards upside down and route 1/4" groves on each end and use a 1/4" thick tube to 'attach' the slabs. I'll use a bondo to lock the tubing into place. That should help the slabs stay together.

When it is completely done I'll put the legs right under where the tubes are

I will keep everyone up to date. I'll do a build thread once I get going on the knots. From reading replies on here and watching some youtube videos I think I've got it all figured out! We shall see