Sealer Epoxy for River Table

[TomInNC]

My brother asked me to make him a river table for his new office. I have the slab ripped and dimensioned, so now it's time to start working with the epoxy. I have never worked with deep epoxy pours before, but based on what I have read and watched, most people seal the live edges that face the "river" to prevent air from the wood from entering the river and creating bubbles while the epoxy cures. What it less clear to me is what type of epoxy is appropriate for the sealing. Right now I have West Systems with the slow hardener as well as a bunch of Ecopoxy Flowcast. The Flowcast is a deep pour product that is very low viscosity, and I am thinking that if I try to paint this stuff on the live edge it will run down and not create a good seal. Should I go with the West Systems for the seal? I know Rockler sells a special sealing epoxy product, but given the cost, I would prefer to use some of the stuff that I have on hand if possible

 

[PeteM]

IMO the best epoxy table info by far is here:

https://www.blacktailstudio.com/

 

[jlwest]

My brother asked me to make him a river table for his new office. I have the slab ripped and dimensioned, so now it's time to start working with the epoxy. I have never worked with deep epoxy pours before, but based on what I have read and watched, most people seal the live edges that face the "river" to prevent air from the wood from entering the river and creating bubbles while the epoxy cures. What it less clear to me is what type of epoxy is appropriate for the sealing. Right now I have West Systems with the slow hardener as well as a bunch of Ecopoxy Flowcast. The Flowcast is a deep pour product that is very low viscosity, and I am thinking that if I try to paint this stuff on the live edge it will run down and not create a good seal. Should I go with the West Systems for the seal? I know Rockler sells a special sealing epoxy product, but given the cost, I would prefer to use some of the stuff that I have on hand if possible

I have used the West Systems epoxy to seal coat. It worked fine.

 

[TomInNC]

I have used the West Systems epoxy to seal coat. It worked fine.

So when you did the seal coat, did you just coat the live edge, or the whole board? I've watched a lot of the blacktail studio videos linked above, and in at least one video I watched, he coats the live edge with epoxy, then hits the rest of the board with de-waxed shellac.

 

[jlwest]

So when you did the seal coat, did you just coat the live edge, or the whole board? I've watched a lot of the blacktail studio videos linked above, and in at least one video I watched, he coats the live edge with epoxy, then hits the rest of the board with de-waxed shellac.

I just did the live edges and any cracks or voids. You can also use poly but epoxy is better.

 

[PeteM]

. . . he coats the live edge with epoxy, then hits the rest of the board with de-waxed shellac.

In one of his newer vids he said he stopped using shellac and now uses tabletop (thin) epoxy to seal the entire slab.
At the other extreme . . . On the one small river table I made I didn't seal anything and just started pouring. I just kept popping the bubbles with a heat gun and it came out okay.

 

[jlwest]

In one of his newer vids he said he stopped using shellac and now uses tabletop (thin) epoxy to seal the entire slab.
At the other extreme . . . On the one small river table I made I didn't seal anything and just started pouring. I just kept popping the bubbles with a heat gun and it came out okay.

The flat surfaces are relatively easy to pop bubbles. Sealing the entire slab works but is a lot of work. A hair dryer also does the trick. I still think you can just use poly on the flat surfaces.

 

[TomInNC]

As I understand it, aside from the cost, the only downside to sealing with epoxy is that this slightly compromises the seal between the slabs and the epoxy river. Is that right?

 

[PeteM]

The Blacktail guy roughs up the epoxy with a wire wheel before the pour and doesn't seem to have any problems.

 

[Mark Johnson]

For the seal coat, I would definitely use the thicker epoxy (West) on the live edge, and in my experience with bubbles I would seal the entire thing as the bubbles keep coming for many hours in some boards. I agree that you should "rough up " that epoxy surface before the deeper pours. Blacktail does have some very good instrctional videos, just make sure you get a recent one because some of his early ones were experiments that did not always work smoothly.

 

[jlwest]

As I understand it, aside from the cost, the only downside to sealing with epoxy is that this slightly compromises the seal between the slabs and the epoxy river. Is that right?

Read the directions for the epoxy for second pour. Usually not a problem. Might vary by supplier.

 

[TomInNC]

For the seal coat, I would definitely use the thicker epoxy (West) on the live edge, and in my experience with bubbles I would seal the entire thing as the bubbles keep coming for many hours in some boards. I agree that you should "rough up " that epoxy surface before the deeper pours. Blacktail does have some very good instrctional videos, just make sure you get a recent one because some of his early ones were experiments that did not always work smoothly.

Good to know. I was getting a little confused as the approach in Blacktail seems to change over time.

Does caulk work for ensuring that the epoxy does not leak under the slab? In one of the Blacktail videos I watched, he mentioned just letting the epoxy flow under the table. This would create a huge amount of waste, though, and I think this would complicate the pour calculations quite a bit.

Lastly, do you typically clamp the slab down before the pour? It seems like videos differ on that as well. Because of temperatures, I have to pour in my basement. The only worktable I have down there is horribly unlevel, so I am planning on putting the mold on the floor. I would need to elevate the mold somehow if clamps are really needed.

 

[Mark Johnson]

I'm not an expert, but caulk does work. I would say clamps are needed, but others with deeper experience might know different. For the things I've done, the epoxy will get through even the smallest gap and puddle. However, I was using some very wormy, and damaged wood for my project. If you have a really flat bottom on the board, and caulk perhaps you don't need this. I would still use clamps.

 

[jlwest]

Good to know. I was getting a little confused as the approach in Blacktail seems to change over time.

Does caulk work for ensuring that the epoxy does not leak under the slab? In one of the Blacktail videos I watched, he mentioned just letting the epoxy flow under the table. This would create a huge amount of waste, though, and I think this would complicate the pour calculations quite a bit.

Lastly, do you typically clamp the slab down before the pour? It seems like videos differ on that as well. Because of temperatures, I have to pour in my basement. The only worktable I have down there is horribly unlevel, so I am planning on putting the mold on the floor. I would need to elevate the mold somehow if clamps are really needed.

I have used hot melt glue.

 

[drw]

If you elect to use caulk or some other sealant, make sure to use a silicone-free product, otherwise you could be creating some significant finishing issues.

 

[Matt Furjanic]

In my experience - and I have done a lot of pours: The most important things in my opinion are: 1. get the amounts of resin and hardener in the correct proportions, usually 50/50. This needs to be really close, and it needs to be mixed thoroughly. Over mixing wont hurt. 2. Keep the slab absolutely level. 3. Don’t try to do it in one or even 2 pours. Several pours are usually required. If you repour within a 24 hour period, no sanding will be required. If you wait a couple days, you will need to sand between coats. 4. Make sure the temperature is above 68 degrees F, and below about 85. Good luck.

 

[Craptastic]

I have used hot melt glue.

That's what I have used in the past. It works well for pours under 7 or 8 gallons, but from what I have been told larger ones can possibly reheat the glue enough from the epoxy chemical reaction and possibly cause leaks. I know someone who does large tables and he hot glues, then finish nails the frame together and then silicone caulks the bottom edges and corners just to be sure he doesn't waste epoxy. Figures he will be finishing the edges afterwards anyhow so if he does a neat caulk job it won't affect where he needs to take material off afterwards.

From a square foot perspective epoxy is usually easily the most expensive material in your build so preventing waste is pretty big. These YouTube guys pouring and brushing it down a countertop and letting it run off and drip all over are selling product with their method. It's a pretty wasteful way to build if you have the means to do it properly. But it does appeal to the weekend project kind of folks who don't realize how much money they will waste down on the plastic covering the floor.

 

[TomInNC]

Thanks for all the feedback. The pour will be a little under 17 liters. Based on the Blacktail studio videos, I was going to use the fast-dry painters caulk (https://www.amazon.com/gp/product/B...L6J8U&linkId=86cf0627e4d437cb433bfe57e81f7525). Would something like that work to prevent epoxy leaking under the slab as well?

Any suggestions for keeping the pour level? As I mentioned above, the only worktable that is in the basement folds up and, because of the hinge in the middle, is horribly unlevel. I am thus thinking that I will build a small platform out of dimensional lumber to get some clearance for clamping, then shim as needed.

 

[Craptastic]

You definitely need to make the frame as level as possible. Epoxy is like water where it will seek it's own level.

 

[John Jimenez]

I’ve used the ecopoxy 1:1 as a seal coat and brush it on. It’s worked well for me.