Does Water Ruin Resin?

epoxy resin pinecone

Are you considering resin for a bathroom or kitchen project and are worried spilling water will ruin the epoxy resin? Or are you considering adding water to thin an epoxy? Either way, you must first understand how water impacts resin.

Water can ruin resin if added before the resin is cured. If the resin is cured and solid, then water will not impact it at room temperature. The only circumstances under which you should be worried about the resin are when water is too hot (beyond boiling) and when it is heavily chlorinated.

In this article, you’ll learn more about how water affects epoxy resin in different situations and what you can do to fix or avoid negative consequences. You’ll also discover what to use instead of water to safely dilute resin and whether there are resin alternatives that are more water-resistant.

There are only two instances in which one wonders about water’s effect on resin. The first is when considering water as a potential thinner for epoxy, and the second is when water gets spilled on cured epoxy floor or countertop. 

Let’s start by tackling the first scenario: if you’re thinking of using water to dilute resin, please don’t. Water will ruin liquid resin by throwing off the consistency of the substances that make up the epoxy. Water is in no way a good diluent for epoxy. 

Instead, you should focus on thinners specifically formulated to decrease the viscosity of a pourable epoxy. Water is a great diluent for consumable liquids, but while it is a taste-neutral addition to most liquids we consume, it isn’t chemically neutral.

With that established, let’s look at water’s effect on resin after the material is cured. Here, you don’t have to worry as water has little to no effect on cured resin. Whether you’ve spilled water on a resin floor or have a resin countertop wetter than a California lawn, the chances of the spill actually affecting the resin are close to zero. 

And that’s for one simple reason: once resin cures, it is sealed and virtually inert. That’s why some resins are considered food safe, and you can serve food on trays made of resin.

That said, not all water affects resin the same way. What we consider water and what scientifically qualifies as water are two different things. H2O is the chemical composition of water but what comes out of your tap is that plus minerals and even preservatives. 

Water isn’t meant to sit in water tankers or even a bathtub. And to discourage the organic growth of bacteria and propagation of viruses through insects like Mosquitos, water is often injected with Chlorine. 

If such water is constantly in contact with resin, its adhesive and the top layer seal can start getting eroded. So the key precaution to take here is to simply avoid exposing the resin to chlorine-spiked water. And whenever any water is spilled on epoxy, you must be quick to wipe it off.

Protecting cured epoxy from water is pretty simple since the resin is a solid that can be moved away from water sources. This is the case unless the actual resin item is something like a water faucet, tumbler, or water softening bed. In that case, you have to make peace with the fact that eventually, the water will take its toll, and the resin will degrade.

And while in most cases, protecting solid resin from water is easy, it is difficult to do so when your epoxy project is curing. In order to protect the resin project, you must make sure you’re not working in an excessively humid environment and make room for ventilation, so even humid air doesn’t stick around long enough to interfere with the curing process.

Before the epoxy is cured, the greatest threat of water exposure doesn’t come from humidity but from people who don’t understand that water cannot thin epoxy the way it thins a concentrated cup of coffee. 

Many novices unwittingly ruin expensive batches of epoxy by pouring water into it. You should use paint thinner as a diluent for epoxy if your epoxy pours too thick or cures too quickly. There’s an entire art to thinning epoxy, and I’ve written an article about that.

And as long as you avoid adding water to liquid epoxy or hosing solid epoxy projects with chlorinated water, the resin is generally safe from water. Room temperature, as well as outdoor temperature in winter, are both acceptable for water exposure, but if the cured resin is immersed in water at a few hundred degrees, it will degrade and start breaking up. 

This is just to warn you not to use resin in water heaters, pipes, or faucets that run hot water or in a tub that will contain warm water. Other than that, the resin will likely cover countertops, floors, and even serving trays in your home. 

As long as you have a Water Snake Moisture Absorber, you’ll be able to clean any water that gets spilled on hard resin. Almost any water-absorbent foam works for this purpose, but I prefer Water Snake because it is multipurpose. You don’t want to buy water-absorbing foam or powder just on the off-chance that you spill water on resin. 

Water Snake Moisture Absorber can be used to waterproof a window or in any other household circumstance where water needs to be stopped from spilling over. With over 497 reviews and ratings, the product is quite well-tested and has an average score of 4.1 out of 5 stars.

Finally, if you’re reading this because you’ve not started your project yet and are wondering how feasible it is to use resin in a construction project where water might often spill, then the answer is that resin is as good as your options. 

If it is resin vs. wood, resin is preferable because it is much more water-resistant than wood. Wood has to be sealed to be virtually waterproof. Most epoxy resin is self-sealing. 

Of course, there are also tiles, marble, and other construction material with varying degrees of water resistance. In-depth comparisons would require an entire article. As of now, you can rest assured that it is okay to go forward with a high-quality resin for a project that is often exposed to water.

Final Thoughts

Water doesn’t ruin solid resin, so you do not need to seal the resin or have a special layer of waterproofing applied over it. Once cured, your resin is as water-resistant as most construction-grade materials, provided your water supply isn’t too heavily chlorinated. When you’re working with resin, avoid adding water to it as this will damage the project before the resin has cured. Instead, opt for a thinner.

Damien Madeira

Damien has been doing woodworking for the last 5 years. He began as a hobbyist with hand tools and slowly worked his way up to own larger machines and mill rough wood into beautiful creations. While still considering himself a hobbyist, he has a passion for woodworking and enjoys working with epoxy as well.

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