Heat Deflection Temperature vs. Temperature Resistance

TLDR: Heat deflection temp is the temperature at which epoxy get's slightly bouncy but returns to normal when cooled and Temperature Resistance is when epoxy becomes permanently damaged. *Short video at the end*

Questions to Ask

• What’s the difference between Heat Deflection Temperature and Temperature Resistance?
• What should I be worried about?
• What should I consider when buying epoxy?

Heat Deflection Temperature

Heat Deflection Temperature (also known as Heat Distortion Temperature) is about the sun and the ambient temperature that you’re going to experience most of the time when you’re doing an epoxy project.

It’s the point at which your epoxy will start to soften – you could dent it with your fingernail or give it a little poke with a popsicle stick and it’s going to feel just a little bit softer than normal – but will return to normal once cooled down. This is usually in the 100°F-130°F temperature range for most epoxies.

An important thing to note about Heat Deflection Temperature is that there is no permanent damage – it occurs when the epoxy is still pushing away most of the harmful things that can happen.

This is a standardized test, the American Society for Testing Materials (ASTM) that gives you peace of mind that your project is going to be safe.

Temperature Resistance

This is basically the point of no return – a sort of catastrophic failure with melting, sticky, tacky, gross results that cause permanent damage. This type of damage typically occurs around the 300°F, 400°F, 500°F temperature range.

The big thing to note with Temperature Resistance is there’s no standardized test, which means that one company could put a really hot pan onto an epoxy project for 10 seconds, say that it’s been 500°F, get it out of there, and give you that claim. It’s not the best marker when comparing resins and companies.

What to Consider When Researching Resins Between Companies

Why do we bring this up? Well, when comparing different companies and their resin options, heat can play a huge factor in which one you decide to go with for your project – for now, we’ll call them Company Y and Company Z.

What does this mean for you and your project? Well, when looking at HDT (the temperature in which things are going to happen to it but it won’t be permanently damaged) Alumilite has measured that. For Amazing Clear Cast Plus, it’s 100°F and for regular Amazing Clear Cast, it’s 130°F. When it comes to Temperature Resistance, Alumilite’s up there in those big high numbers (400°F/500°F) like you’ve seen in other companies.

With other companies like Company Y and Company Z, they talk about the 500°F and the 400°F temperature resistance, but what they don’t talk about is the standardized Heat Deflection Temperature test. From Alumilite’s in-house testing, we know that other brands out there are plus or minus about 10°F of our HDT temperature for our products here.

This is just a reminder to be mindful of the numbers you see out there and make sure you’re reading the right thing.

Watch the Video - Alumilite Explains: Epoxy Heat Resistance vs Heat Deflection Temperature