Why does my resin not harden?

Resin is a magical plastic that can be used to create beautiful works of art. It comes in two parts: resin part A and resin part B.

The resin and hardener need to be mixed together in order for the magic to happen and the resin to harden. You don’t want to use both parts on their own, because when you do, something strange happens.

Why does my resin not harden?

When you pour resin into a mold, it will form a liquid that hardens over time when exposed to ultraviolet light. The properties of the colorant in the liquid determine if it will cure properly under UV light. If you use the same colorant for all your pieces, your resin will set faster.

Here’s an example of an incorrect combination:

1 tablespoon of silver oxide with 1 ounce of Premo White or Premo Blue

Premo is a brand name for a brand of resin made by Krylon, Inc., which was founded in 1938. It’s not necessary to use this particular brand of resin because there are several others that work just as well; however, we decided to go with this one since Premo has been around the longest and is considered synonymous with the word “resin” (we’re going to say more about brands within this guide later on.)

Why is my resin still soft?

One of the most common questions I get asked is “Why is my resin still soft?” Often it seems that crafters start out with one problem, but end up compounding it, which leads to another and then another. Before you know it, something you thought would be easy turns into a real nightmare.

Why is my resin still soft after 24 hours?

The top reason your resin is still soft after 24 hours is that the temperature is too low. Cold temperatures slow down the curing of resin, in some instances causing it to take up to 48 hours to fully cure.

There are other reasons your resin didn’t cure correctly:

  • You’ve added too much hardener (or too little)
  • Your resin and/or hardener has been improperly stored
  • You’ve used a different brand of resin or hardener
  • You’ve used an expired product

How do you fix soft resin?

“I’ve got a question,” said the customer, while squinting at a honeycomb that was sitting on the counter.

“What can I help you with?” I asked.

“My honeycomb isn’t hardening.”

“Not hardening? That’s weird,” I answered. “Has it been cured for long enough?”

“Well, like 24 hours.”

By now there was a hint of worry in his voice. “How much more time have you got?” he asked cautiously.

I stepped behind the counter and pulled out my chronograph to check the resin temperature and working time of all the other resins currently drying in their trays.

Why does resin take longer to cure?

So, you’ve mixed your resin and poured it into your mold, and now you’re wondering why it hasn’t cured yet. I can tell you that there are many factors that play a role in the curing process of resin, some of which we have no control over. We can however ensure that everything is set up for success before we begin our project. The big question is: Why does resin take longer to cure?

  • It needs more time to cure

This one may seem obvious but sometimes the reasons for the slow curing process are not as clear-cut as they should be. To put it simply, each type of resin has a different curing time and this will vary depending on whether or not you added any colorants or additives such as mica powder.

  • The temperature in the room might be too low

ArtResin cures faster when stored in warmer environments (above 70°F). If your room is cold then this could be one of the reasons why it’s taking longer than usual to cure properly.

Will epoxy resin harden without hardener?

Hardener is added to epoxy resin to initiate the curing process. When resin and hardener are combined, a chemical reaction takes place and the mixture turns from liquid to solid.

The curing time can be affected by the temperature of your working environment, not measuring parts correctly, or even old product that hasn’t been stored properly.

Can you dry epoxy with a hair dryer?

WHAT NOT TO DO: If you’re working with resin and it isn’t curing, do not try to use a hair dryer to speed up the process! That’s a recipe for bubbles.

WHAT TO DO: If you want to cure your resin faster, get yourself a heat gun (from the hardware store) or even better, an infrared lamp designed for resin work.

What happens if you add too much hardener to resin?

If you add too much hardener, the epoxy will dry perfectly, but be brittle and prone to cracking. With too little hardener, the resin will never cure. If you add way too much hardener (we’re talking more than 30% additional! Wow!) the resin will cure so quickly it will heat up and bubble.

In other words: there is no such thing as “perfectly balanced” in chemistry. And that’s OK! You just need to follow a recipe for epoxy resin in order to get it right every time.


While there is no exact “right” way to do things when it comes to resin, there are a few tried and true tricks that can help you understand why your resin isn’t hardening.

Resin doesn’t cure properly because of varying temperatures between the two parts, improper measuring, contamination of one part or both, insufficient surface area or thickness, and overhandling.

Photo of author

Martin Flood

Martin Flood has been working in the construction industry for over 20 years as a general contractor with expertise in remodeling projects that are large or small. He has furthered his career by specializing in epoxy resin flooring, providing excellent service to both commercial and residential clients. Martin’s experience enables him to offer professional advice on how to choose the right type of project based on your needs and budget.

Leave a Comment