When it comes to forming strong bonds, both epoxy and resin glue can be strong, but epoxy is stronger. Both types of adhesives are good for home repair and construction projects. The main difference between the two types of adhesives is the drying time. In general, (but not always) epoxy coating resins are harder than casting resins.
Casting resins often have the ability to vary mix ratios, ultimately allowing for a variation in hardness. The best example of this is seen in molten resin used as fake water for a vase. If a casting resin is used without flexibility, the vase will crack as the glass expands and contracts. Therefore, more flexible blends are needed for these types of applications, which can usually be achieved by varying the amount of hardener (curing agent) used.
However, each and every casting resin is different; research each one to determine its suitability for your individual project. Finally, coating epoxies usually offer superior scratch resistance compared to resins. Epoxy coating resins are thicker compared to casting resins. This is because the cure speed for casting resins is very low.
The lower cure speed creates low heat, thus creating thicker layers. This is why casting resin is not used in coating applications, since the resin is much thinner and seeps to the sides of the object. Build a frame around your object to protect it. Epoxy is a specific type of two-part resin.
Epoxy resins are the most commonly used type of resin for making crafts and creating resin art. Because they are the easiest to measure and mix, epoxy resins are the ones I recommend for resin beginners. Epoxy is generally more expensive than resin, due to its strength and formulation requirements. Resin is more popular for making crafts and jewelry, due to its low cost.
However, remember that you get what you pay for. Epoxies and resins are adhesives commonly used in repairs to homes, automobiles, airplanes, and ship buildings. This is because most of these unlimited epoxies have been slightly modified to suit the particular needs of the project. Most epoxy coating resins and casting resins used by the average DIY artist are not high heat resistant epoxies.
While all epoxies turn yellow over time, some manufacturers are better than others at resisting UV light. Alternatively, coating epoxies can be used for casting applications, but may need to be poured in multiple layers. Tabletop epoxies are preferred for pouring onto flat surfaces such as table tops, bars, counters, resin art, or other flat items, since it is a self-leveling epoxy. Most casting resins and epoxy resins that are intended for the average do-it-yourself enthusiast are not high-temperature epoxies.
When you begin to compare the many shapes and variations of epoxies, glues and resins available today, the results can cause you to scratch your head.