How to Remove Epoxy Resin That Did Not Cure

sticky epoxy in cup

Working with epoxy resin can be fulfilling but can disappoint as well, especially if your pour doesn’t cure perfectly. From suspended bubbles to perpetually viscous top layers, epoxy resin projects can be unpredictable, which makes them all the more rewarding when the epoxy resin cures perfectly. As a craftsperson, you must be willing to remove epoxy resin that hasn’t cured perfectly and redo the parts that need to be improved.

To remove epoxy resin that did not cure, you need to scrape off the most vicious top layer, then use a heat gun to liquify the semi-cured layer underneath. Finally, you need to use lacquer thinner, alcohol, or acetone to remove any pigment or remaining traces of epoxy.

In this article, you’ll learn how to execute each step of epoxy resin residue removal. You will also learn the specific surface and resin considerations alongside other tips for safety at each step. Reading this article will save you a lot of time and effort in epoxy resin removal and even in do-overs of your epoxy project, as you will discover why resin does not cure properly.

Scrape the Surface

The first step in getting rid of uncured resin is an instinctive one. The urge to scrape off the resin is right, but the tools used for it are often wrong. A hand, despite being gloved, is a bad scraper. You must opt for a metal scraper in most instances. 

If your project involves wood and will be sanded afterward anyway, the metal scraper is perfect because it is slim enough to get significant amounts of resin out. It also has the strength not to bend when a particularly vicious patch puts up resistance.

If you face resistance with a metal scraper, you’ve already gotten everything off that you could and must proceed to the next step. With plastic scrapers, the story is different. These are inefficient but are sometimes necessary when metal scrapers pose a threat to the project’s health. 

If you’re working with materials that will visibly scratch if scraped with metal, you have to downgrade your scraper choice to plastic. The advantages of metal are drawbacks of plastic as it bends more easily and is often thicker. Plastic scrapers are thicker mainly because to have similar durability as a metal sheet, the plastic sheet must be wider, or it bends.

In other words, if your project involves clear resin preservation of suspended items, you’re not going to be very lucky at this stage. Please do not push your luck, though. Do not fatigue the scraper or yourself getting more resin off than is effortlessly possible.

Heat to Liquify

Resistance will often come once you get the low-hanging fruit off with a plain scraper, and getting any more off isn’t the point of the first step. The first step exists only to make room for this one. You must head the resin to liquefy it. Liquifying is simply lowering the viscosity of the resin, so it acts like a liquid. 

You might be thinking that you can do this before scraping as well. You can, but it will cure the resin halfway through the removal because you’ll liquify a larger quantity. 

This rings truest for fast to mid-curing epoxy resins. But if you face an uncured epoxy resin problem, then quick curing isn’t the likely culprit. The more likely candidate is a bad epoxy thinner or too much liquid pigment.

Regardless of the cause of the curing issues, you need a good heat source that impacts the epoxy without affecting the surface as much. Handheld heating solutions are preferable for smaller projects. If the resin is almost entirely off, then a blow dryer might be all you need. Often a heat gun is necessary though you must hold it at a distance.

If the thinner is the problem, heating to liquefy works well. However, with curing issues that occur due to liquid pigment affecting the proportion balance, there’s the risk of color residue.

Clean with Thinner

Using a thinner helps get the last of what’s left of the epoxy resin off the surface. The choice of thinner depends on the project and your preferences. The word “thinner” usually gets people thinking about epoxy thinner in this context, but it refers to lacquer thinner.

An epoxy thinner is a medium used to make epoxy resin easier to work with. Lacquer thinner is used to get hardened resin (epoxy or other material resin) off a solid surface. However, that’s not the only product you can use at this stage. 

A traditional thinner works, but you can also use acetone, which is often used to get epoxy resin off the craftsman’s hands. Using gloves and removing them afterward is much friendlier for the skin as acetone can be unhealthy for the epidermis.

This brings us to the surface considerations when choosing a thinner. The primary function of thinner is to get rid of the resin once its viscosity is reduced by heat. 

How low the viscosity is, depends on the surface. After all, holding up a heat gun to plastic isn’t as wise as doing so with wood. This once again circles back to the material on which the uncured resin rests.

If the resin deposit is on a wooden surface, you have the most freedom. You can use lacquer thinner, acetone, or rubbing alcohol to get it off the surface. 

If it sits on plastic, you have to be the most cautious, and using anything stronger than acetone will compromise the plastic. Finally, you have glass and metal, which are conducive to lacquer thinner though you must make sure you don’t rub the surface too aggressively.

Final Thoughts

Whether there’s leftover resin that’s cured halfway or you’ve overpoured epoxy resin, and the top layer is unstable, you need to follow the low to high effort formula to get rid of what hasn’t cured properly. For this, you must first scrape what can be taken off right away. You might discover that you don’t need to do anything else but if there’s leftover resin, use a heat gun to liquefy it and clean it with a thinner. Keep in mind that you might have to repeat these steps a few times before the surface is free of epoxy resin.

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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