How To Thin Epoxy: What Works, What to Avoid, and When to Use a Different Resin

If your epoxy feels thicker than you want, you might be wondering how to thin epoxy to make it easier to mix, pour, spread, or work into detailed areas. The good news? In many cases, you don't actually need to add anything to your epoxy. 

Temperature and the type of resin you're using have a big impact on how easily epoxy flows. Before reaching for acetone, alcohol, or another solvent, it's worth understanding why your epoxy feels thick, and whether thinning it is actually the right solution. 

Why Would You Need to Thin Epoxy?

There are a few reasons makers might want their epoxy to flow more easily. You may be coating a surface, trying to get resin inso small details, working with porous wood, or simply noticing that your epoxy feels thicker than usual. One of the biggest factors is temperature. 

Epoxy tends to become more viscous when it's cold and flow more easily when it's warm. If you're working in a cool garage, basement, or studio, temperature may be the issue, not the epoxy itself. Before changing the formula, check your workspace and make sure you're also using the right resin for what you're making. 

For example, someone working on small art pieces, trays, jewelry, or detailed molds may prefer an artist-focused formula like Studio Series Epoxy Resin. On the flip side, someone making a river table or large encapsulations needs a resin specifically formulated for deeper pours like Deep Pour Epoxy Resin. Sometimes the answer to how to thin epoxy is simply choosing a resin designed to flow the way your project needs it to. 

How to Thin Epoxy Without Adding Solvents

If your epoxy is simply too cold or thick, start with gentle warmth. Use a warm water bath. 

Before mixing, keep your resin and hardener bottles tightly sealed and place them in a container of warm water for a short period of time. The goal is to gently warm the material, not make it hot. Once warmed, remove bottles, dry them completely, and then measure and mix your epoxy according to its normal instructions. 

Even a small amount of water getting into your resin or hardener can cause problems, so make sure the bottles are completely dry before opening them. Also keep in mind that temperature affects more than viscosity. Warmer epoxy generally reacts and cures faster, which can shorten your available working time. 

Can You Thin Epoxy With Acetone?

This is one of the most common questions around how to thin epoxy. You may see acetone recommended online because adding a solvent can reduce the viscosity of some epoxy systems. The problem is that you're also changing the chemistry of the product. Adding acetone can potentially affect how the resin cures and the physical properties of the finished piece. There also isn't one universal amount of acetone that's appropriate for every epoxy formula. 

That's why we don't recommend automatically adding acetone to Promise Epoxy products just because you want a thinner consistency. Our formulas are designed to be measured, mixed, and used as formulated. If flow is the problem, start with temperature and product selection instead. 

Can You Thin Epoxy With Alcohol?

Alcohol is another DIY epoxy thinner you'll see mentioned online. The same warning applies. 

Adding alcohol or another solvent may make a mixture feel thinner, but it can also alter the way resin behaves and cures. Different epoxy systems respond differently to additives, which makes broad recommendations like "just add a little alcohol" risky. Unless the manufacturer of your specific epoxy tells you to add a solvent, it's better to leave the formula alone. 

Don't Change the Resin-to-Hardener Ratio

This one's important. Never try to thin epoxy by adding extra resin or extra hardener. Two-part resin systems rely on the correct ratio of resin to hardener for the chemical reaction to work properly. Changing that ratio can result in epoxy that stays soft, sticky, or never fully cures. 

Always follow the mixing ratio listed for the specific product you're using. 

For example, Promise Table Top Epoxy uses a 1:1 resin-to-hardener ratio and is formulated for surface coatings, table tops, counters, wood sealing, and similar projects. If you need a different consistency or pour depth, switching products is a much better option than changing the mix ratio. 

How to Thin Epoxy for Wood

Working with wood is another common reason people look up how to thin epoxy. You may want the epoxy to penetrate porous areas, fill small cracks, or flow more easily across the surface. Again, warmth can help. 

Making sure both your resin and your project are at an appropriate working temperature can make the epoxy easier to spread without adding a solvent. Product choice matters here, too. Using the right epoxy for the job usually gives you better results than trying to modify a formula that wasn't designed for that application. 

Does Thinner Epoxy Help With Bubbles?

It can. 

Lower viscosity resin gives trapped air more opportunity to rise through the mixture and reach the surface. But that doesn't mean you should add thinner to your epoxy just to eliminate bubbles. Temperature, mixing technique, pour depth, project materials, and the epoxy formula itself all plays a role. 

If bubbles are a major concern for art and craft projects, Promise Studio Series Epoxy Resin was developed with excellent bubble release along with artist-grade clarity and a smooth, self-leveling finish. 

You can also learn more in our guide to How to Get Bubbles Out of Resin. 

So, Should You Thin Epoxy?

In most situations, we recommend using epoxy as it was formulated by the manufacturer rather than adding solvents to it. If your resin feels too thick, first check your working temperature. Gentle warming goes a long way. 

If the viscosity still isn't right for what you're making, consider whether you're using the right type of resin for the project. But if you absolutely must add a solvent we recommend acetone. However, changing products is often much safer, and more predictable, than changing the chemistry yourself. 

Find the Right Resin for Your Next Project

Different projects need different things from their resin. That's why Promise Epoxy makes formulas for art, coatings, deep pours, fast curing projects, UV-sensitive artwork, and more. 

Shop Promise Epoxy and find the right resin for your project →