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.
What I mean by that is resin will do what it’s supposed to do. We, as crafters and artists, need to work within the confines and the limits of the resin to get the results we want.
How do you do that?
Let’s start with resin chemistry
Okay, we’re only going to back to high school chemistry for 30 seconds. Hang with me…
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, 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 high school flashback. You’re welcome.)
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. My go-to choice for resin river table project is 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 of 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:
–medium density fiberboard 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 70’s 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 over a decade ago. It’s why I wrote the book, 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?!’
Unpublished Blog Posts of Resin Obsession, LLC © 2022 Resin Obsession, LLC