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How Strong is Epoxy Resin on a countertop surface? To uncover that answer, we must look at some factors that determine the strength of a substance. So that we are talking the same language and using apples to apples, let's define some of these terms and factors.
Hardness is a material’s resistance to deformation. A Durometer measures the hardness in polymers, elastomers and rubbers. Hardness may be defined as a material’s resistance to permanent indentation. The durometer scale was defined by Albert F. Shore, who developed a measurement device called a durometer in the 1920s. He used multiple scales depending on the material used. For Epoxy Resin, you would use Shore D, Shore hardness value may vary in the range from 0 to 100. Another Scale of measurement for Minerals is Mohs Scale for Hardness. This is a different scale for measuring the scratch resistance of only natural occurring minerals. As an example of Hardness, let's look at some everyday materials that most people are familiar with.
Shore D Mohs Scale of Minerals
Concrete (Varies) 50-70 Granite/Marble 6-7
Car Tires 5-10 Diamond 10
Hard Hat 70-80
Epoxy Resin 78-85
Compression Yield strength is the stress required to cause plastic deformation. Plastic deformation is the permanent change in the shape or size of a solid body without fracture, resulting from sustained stress beyond the elastic limit. Cylinder shaped specimens are placed in a test machine that applies an increasing compressive force until plastic deformation weakens the sample. The highest force recorded prior to deformation is the Compression Yield Strength. The Compression Yield Strength is approximately 110-130 MPa.
Tensile Strength is the stress that is required to fracture the epoxy and cause a failure. Dog bone-shaped specimens are placed in a test machine that applies an increasing tensile force until failure. The highest stress recorded prior to failure is the Tensile Strength. The Tensile Strength of Epoxy Resin depending on type is approximately 68-80 MPa.
Now before we loose interests in all of the different scales and terms. Let's just apply what we have learned so far. The strength of a material is based on it's Hardness, Compression Yield Strength and Tensile Strength. In other words, depending on it's application, we may want a material that is Hard, won't deform from compression, and won't fracture very easily. As you can imagine, it is difficult to get those three items in a material. Certain materials have a lot of one, but not maybe so much in the other areas.
The Actual strength of Epoxy varies on brand and application of that brand. See video link below.
Also the thickness of the pour of your substrate is important to take into account. Most Countertop Epoxies pour at around ⅛ inch depth over construction substrate. Then full hardness occurs about 30 days after initial pour.
Here is a link to another video from an Epoxy Manufacturer on it durability.
Lastly, this next link was really fun to watch more than anything else. Want to see what happens to an epoxy table sample that is shot with a .22 rifle. You will be amazed at the results.
I use many brands and different Epoxy's based on application. I have recommendations that I will be happy to share with everyone, but this forum is strictly so you can equip yourself with knowledge to make your own informed decision.