When it comes to using epoxy to make a resin table, there is a cardinal rule you have to follow. Whether you like it or not.
The resin always wins.
It’s kinda cool to think you might have a chance in the resin fight club. But resin will do what it’s supposed to do. IF…
Crafters and artists work within the confines and the limits of the resin to get the results we want.
Yes, We’re manipulating the resin to get what WE want.
How do you do that?
Let’s start with resin chemistry.
The side A of a resin kit is epoxy. It has long chains of molecules that contain several elements. The side B is an amine-based chemical. It is specifically formulated to link with that epoxy. (That’s why using one manufacturer’s resin with another manufacturer’s hardener can be a reason why your resin doesn’t cure.)
By themselves, the resin and hardener don’t do much, but the magic happens when you combine them. The parts of each merge to start a chemical reaction, which crosslinks all the molecules. This crosslinking produces heat and eventually creates a solid mass of resin. Feeling your resin get hot is a good thing. This is what we see as resin curing.
Gee Katherine, thanks for the chemistry lesson. But how does this help me make an epoxy river table?
Ah, resin padawan. When you are pouring resin in thick layers, as you do for making the epoxy table, there can be a lot of heat. And unfortunately, that isn’t always a good thing.
The thicker and larger the area of resin poured, the hotter the mixture gets. As more crosslinking occurs, more heat is produced, adding to the heat of the mass of resin. A larger, thicker mass of resin is going to get hotter and take longer to cool than a thinner, smaller mass of resin.
So why does this matter?
As the mixture heats, and then cools, it shrinks towards the center of the resin pour. While a little bit of shrinkage is normal, excessively hot resin cools and shrinks a lot.
What’s the worst-case scenario? (I always loved those survival books.)
When the center of the pour no longer absorbs the shrink, a crack develops.
What does this ultimately mean?
The thicker the pour of epoxy for your table, the more you need to worry about the resin reaction heat.
(Yes, I could have started with that, but then you wouldn’t have had the awkward high school flashback.)
So what should you do?
Here are my tips to help you craft that amazing epoxy resin river table:
By the way, these tips work for any project where you want to pour thick layers of resin.
*First, you need to use a resin designed for a project like this. That’s why we’ve got the Resin Obsession deep pour epoxy. This resin creates heat slowly, so you don’t have to worry about cracking. You can pour it in layers up to two inches thick in one pour.
*For layers of more than two inches, pour a layer, then let the previous layer completely cool before pouring the next layer. The heat of layers is additive, meaning any heat from the first layer will add to the heat of the reaction to the next layer. By letting the previous layer fully cure before pouring the next layer, you will see a line between layers when looking at the side. But it will be less likely that you will see a crack when looking through the top of your project.
*Your mold box can contribute to heat retention. Mold boxes made from wood retain heat and make overheating and cracking more likely. Mold boxes made with thick lumber planks are easy to make but are also excellent heat insulators. Better mold material choices include:
-melamine board
-polypropylene
-HDPE plastics
-aluminum
-medium density fiberboard (MDF) coated with Tyvek plastic
*Look for other ways to get rid of extra heat. Elevate the mold box off your surface, then use a fan to generate airflow underneath and around it. You also want to be sure your casting room is not too warm. The low 70s F is ideal.
*Be careful not to overheat the resin for your epoxy table. Warming resin before casting is a great way to thin the components, making it easier to mix. This warmth, though, adds to the heat of the reaction. Warming up your resin for too long can cause reaction overheating. If you don’t believe me, you can see what happened when I overheated resin.
Overwhelmed with everything there is to know about resin?
I get it. I felt the same way when I started creating with resin. It’s why I wrote the ebook, Resin Fundamentals. I share the important details you need to know. Get a clear path on how to make something with resin that will have people saying, ‘Wow, you made that?!’ Buy the PDF book now and get a download link in minutes.
Unpublished Blog Posts of Resin Obsession, LLC © 2023 Resin Obsession, LLC
Not a new tip about curing but from a newbie like myself it is a hard-learned tip.
When mixing the hardener + epoxy stir until the cloudy mix turns almost clear.
If you don’t do that you’ll get a permanently sticky mess.
If you do that it’ll cure nicely.
Yes, that’s very important as well. Thanks for the reminder!
When I pour resin into my wood projects for turning I always pre-coat the sides first which helps prevent air bubbles.
That’s a great tip, Nelson. Thanks for sharing!
Do you use the epoxy/harder to coat the sides? How deep does it have to be for this step?
I think he means that you should apply a thin coat of epoxy (with a brush) to the wood that’s going to be inside the epoxy. This will prevent air inside the wood to exit and show bubbles in the epoxy.
Other issue with epoxy is air humidity. Anything above 70% isn’t a good thing.
I’m new to using resin what do you mean by precoat
I am new to resin pouring and have an irregular shaped end live edge piece of cherry that has some large cracks in the end. I don’t want to straighten/cut the end off but curious how to build a mold or box to accommodate the end so the resin doesn’t just run out…ideas?
Had a similar situation myself. It’s pretty common.
Build the frame around the piece or at least the ends that have the cracks.
Get some tuck tape, attach it to straight pieces of plywood, and attach that to the project piece.
Attach additional tuck tape to any exposed cracks on the sides or underneath the project piece where resin might want to leak out from.
Then pour.
But be careful not to over pour. You might want to cover the area around the crack(s) you’re filling.
Unless you’ll be planing or sanding the whole thing off afterwards.
Removing resin through sanding or with a card scraper is easier than I thought it would be but if you’re using pigment it can get through the wood fibers around the filled crack where you don’t want to see discoloration.
And don’t forget to thoroughly mix the resin to avoid a sticky mess.
Can “lakes” of epoxy be poured into large tabletop centers, or is the risk of the wood holding the dimensions firm while the epoxy contracts a legitimate risk? I only see rivers…. in photos, anyway. Are rivers always used to allow the epoxy to move on its own?
If this is not a clear question just let me know
Hi George, yes, you can do a lake.
I’m trying to do a river table with live edge and this will be my first. I’ve read online so many different deep pour articles but I’m getting mixed info and would love some clarification for simplicity sake. The “River” will be about 2″ thick, what resin/epoxy do I need so I can pour ONCE and not many different layers that take lots of time?
Hi Seth, for a project like this, the Resin Obsession deep pour resin works great. You can pour it up to two inches thick in one pour. You can buy it in several sizes in our store here: https://shop.resinobsession.com/collections/resin/resin-obsession-deep-pour-resin
Be sure though, to follow the tips in this article to make sure your resin doesn’t get too hot and crack. Since this is your first time making a project like this, you may want to try a smaller test piece to see how it works.
You all provide excellent advice and ideas. I have an issue I don’t see covered.
I poured a deep resin table. I poured 8 coats to hit two inches thick. There is about 1/2” of resin over the top.
The final coat is still just a little tacky. No pockets of resin, but the entire surface is sticky.
My question is what is the best way to sand it smooth while not marring the surface?
I’m looking for help!
Thanks
Hi Dave, you are going to have to sand it with coarse sandpaper. Then, work down to fine sandpaper to bring back the shine. This article explains more: https://resinobsession.com/resin-frequently-asked-questions/how-to-sand-resin-smooth/
I have a question .im sorry for my ignorance in advance. Do you go to a table top epoxy after you do ur deep pourepoxy
Hi Tracy, what are you trying to make? The deep pour resin is meant to fill vessels and molds while a table top epoxy is meant to coat surfaces.
I have this same question. I’m making a live edge river bar top that will be outdoors. I understand the risk but since it’s for my own house, I’m willing to take the chance. I have purchased a deep pour epoxy for the river portion and will be using Total Boat Halycon Clear varnish for the final top coat as added protection from UV and water exposure. My question is, can I use the deep pour epoxy for top coat as well, and as a pre-coat on my live edges? Or do I have to purchase a separate table top epoxy for this?
Apologies if a similar question has already been asked but here we go. I have a life size skull (resin – not real!) My idea was to surround it with aquarium plastic plants and place it in a cube or tube and submerge it in resin with a dark green coloring (imagine the bottom of a lake)
Would I see layer lines looking from the side if I’m just pouring two inches at a time? And would this end up ridiculously expensive if it were 10” x 10” x 12” high?
Thanks
Hi Andrew, what a neat project! You can minimize the line between layers by pouring the next layer while the previous layer is in the gel phase. This article explains more: https://resinobsession.com/resin-frequently-asked-questions/resin-gel-time/. I don’t know what you consider expensive, but it’s going to take about 5 1/2 gallons of resin. This is the resin I’d use for a deep pour project like this: https://shop.resinobsession.com/products/deep-pour-slow-cure-clear-epoxy-resin-for-river-tables-1-1-2-gallon-kit
Andrew,
I have the same queation! Can a deep poor epoxy be used as a 1/4 inch surface epoxy, or would a deep pour not work this way and cannot be substituted for a top coat epoxy?
Hi Jason, deep pour epoxies don’t work as a top coat because they don’t self-level. This article explains more: https://resinobsession.com/resin-frequently-asked-questions/types-of-epoxy/
Similar area for question – we have used your deep pour for a beautiful island! What do I do to get the tops flush / seal? We don’t want any scratches and I’m nervous to mix the deep pour with a top coat and ruin this 8’ by 4’ island!
Hi Tia, this sounds so cool! I want to be sure I understand what you want — You’ve made a table with our deep pour resin and you want to coat it with a glossy coat of resin and non-rounded edges? Do I have that right?
Yes, that is correct!
If you try to pour a second layer when the first has gelled, do you run the risk of exothermic runaway? I’m not actually thinking of a river table, but of a pyramid. I really hate the sharp layer lines. Or if I poured while gel maybe only an inch instead of two?
I know I have heard you can reduce lines by sanding between layers, but it is hard to sand in a mold and not break the seal and get seepage down the sides.
Hi Jodi, yes, you do.
Can you use doming epoxy over deep pour to have a finished AND protected (scratch-proof) top on a project? (An island, but like a river table)
Hi Tia, are you using a mold to create the island?
It is already off of the MCF board we used as a mold.
In that case, yes, you can use the doming epoxy as a durable protective coating. https://shop.resinobsession.com/collections/resin/doming
I’m currently finishing my epoxy resin coating on my wood slab. I think i hv passed the pouring stage, took 3 layers to make it even. Now proceeding to polishing stage. Any advise,?
Hi Yazid, we’ve got a polishing article here to help: https://resinobsession.com/resin-frequently-asked-questions/how-to-polish-resin/
Hi there, a bit of a unique question. I have a think piece of reclaimed cedar slab that I am using to make a bar counter top. it has some really cool features but also has some insect damage leaving a bunch of pock marks ( I mean a lot of these ) over the surface as well. I was intending to make these into a feature. They aren’t very deep in most cases. Maybe 1/16 or and 1/8 deep. I was intending to drip resin into each one and not worry if there was a bit of overpour. Then was thinking I would sand off any excess. Will it work .. and will it work well I guess.
Yes, Paul, that will work.
When coating the top and bottom of a charcuterie board how do you and pour line from top to bottom? Also do you pour the thin epoxy coat on the top or bottom first? Thanks for your help!!
Hi Mike, we’ve got an article explaining that here: https://resinobsession.com/resin-tutorials/resin-charcuterie-board/
How do you calculate the volume of epoxy needed?
Wanting to take a butcher block top and intersperse the same width of the wood strips with channels of epoxy.
Would it just simply be the Height x Width x Length of each channel, or is there expansion/contraction of the resin I need to account for? I would need the deep pour for the channels,but would I want to use that for the entire top as I would also need to coat across the entire top surface. Wood strips would be 1.5 inches thick so the deep pour might be within your application. I would be doing a table plus 2 parbeque carts, one with Weber grills installed. Is there a heat concern?
Hi Greg, we have a resin volume calculator here: https://resinobsession.com/resin-calculator/
What about dust in between layers? How do you protect from that?
Try covering your project will a plastic container. Thats what I use to avoid dust and debris getting in!
I have part of a tree that once cut down, three feet was then cut in half lengthwise, it was dead inside and left a really cool rough looking type of ravine, very dark almost burnt looking. The bottom and the top on each side of the ravine is sandered smooth. It’s four inches deep on the ends and goes to two inches going towards the middle from each end, it then goes to one and a half inches and back to two inches in the very center. I’m wanting to add a dragon and a dragon slayer to the ravine. How do I get the amount of resin I need for the pour,? It’s my first time using resin.
Hey there! You can use our resin calculator on the website. I would be mindful that pieces like that eat up A LOT of epoxy.