So let’s see here:
Epoxy Resin. Resin Art. Epoxy Flooring. Casting Resin. Table Top Epoxy.
These terms have been used so frequently in the same conversations. It almost feels as though they are used interchangeably. Can you use Casting Resin to cover your countertops? Do “epoxy” and “resin” really mean the same thing?
The Short Answer
Well… simply put: liquid resin is a malleable substance and the added adjective “epoxy” means this resin will solidify completely. Epoxy Resin comes in two part systems which manufacturers have specially designed and labeled for different projects. So while Casting Resin and Table Top Epoxy are used for different things, they are both still Epoxy Resin. The real difference lies in the characteristics that make these systems unique from each other.
The Long Answer
On Epoxy vs Resin
Epoxy Resin is a type of resin plastic that is thermosetting, which, as the name implies, means that once it is mixed with the catalyst (part B hardener), it will chemically heat, set, and harden. This also means there is no way to undo it. You can heat it and it will ultimately be destroyed, but it will not melt and become separable into its original two parts.
For further context, think of acrylic resin. This substance can be manipulated with heat multiple times. And polyester resin, while a thermosetting plastic as well, is less favorable than epoxy resin because it has a foul smell and is quite toxic.
On Casting Resin vs Table Top Epoxy
The most obvious difference between Casting Resin and Table Top Epoxy is the project application, or designed purpose.
Casting Resin, as the name suggests, is used to make casts in molds. Typically, this is used for pouring into molds of varying thickness and shape, to make things like jewelry and paperweights.
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Table Top Epoxy is used for coating surfaces, hence the “table top” label. This type of epoxy resin should be poured in layers between 1/8″ and 1/4″.
It is possible to use either system for a project other than its specially designed purpose. However the results are often largely flawed and unusable.
What Makes Them Different?
Every beginner seeking to indulge in this wonderfully creative outlet should take a moment to learn the difference between the two main systems of epoxy resin: Casting Resin and Table Top Epoxy.
There are many factors that define the systems that make Casting Resin and Table Top Epoxy different – and they are all in direct relation to each other. These varying characteristics are:
- Cure Time
- Viscosity
- Working Time
- Pour Depth (Intended Maximum)
- Mix Ratio
- UV Resistance
- Heat Tolerance
- Hardness
Viscosity:
– Casting Resin is designed to have a thinner viscosity. This gives the resin a low density mixture and a thin pour stream. This makes it the perfect resin to use with molds to make casts as the thin liquid will surely take the shape of the finest details. If used in pace of Table Top Epoxy for a flat project like a countertop, beware of its thinness as it will run quickly across the surface and likely spill over the sides if the project isn’t properly set in a built dam.
– Table Top Epoxy has a much thicker viscosity. This results in a higher density of reactive product per cubic inch of poured liquid. And because of this, Table Top Epoxy has a thicker pour stream and a shorter curing time. This makes it ideal for pouring simple flat planes like river tables and countertops.
Cure Time:
– Casting Resins can take multiple days to cure, usually about 36 to 48 hours, and it can take as long as 18 hours to gel. While these times ultimately depend on the manufacturer, they are due to the thin pour stream of the liquid resin. Meaning: the low density of the mixture requires a longer time to complete the chemical reaction that generates the heat needed to cure. This same characteristic is what allows for thick casts to be poured at once.
– Table Top Epoxy takes significantly less time, gelling in a matter of 30 minutes in most cases. A full cure can take as little as 12 hours or just 1 day. The thicker pour of this type of epoxy resin allows for more heat to be generated in a shorter amount of time compared to Casting Resin. Unfortunately, this is why it is necessary to pour this product in very thin layers, otherwise the product will generate too much heat and possibly form unsightly flaws like cracks and bubbles.
- For more information on what happens when epoxy is poured too thick, check out our other article: “What To Do About Thick Epoxy”
- For more information on pouring layers properly, check out our other article: “How To Pour Layers With Epoxy Resin | Table Top Epoxy”
Working Time:
– Casting Resin has a longer working time, and this is evident in its slow cure time. The mixture as a whole needs much longer for the entire chemical reaction to complete – meaning it takes a long time from the moment it is mixed to the time it is totally hardened. So, this gives you a long window of time to mix part A and B together, add colorants, pour into different molds, and so on. You don’t have to be particularly worried about your liquid mixture solidifying before you have it poured out.
– Table Top Epoxy has a shorter working time, which of course means it also has a shorter curing time. Compared to Casting Resin, it takes a fraction of the time to cure from the moment the resin (part A) is mixed with the hardener (part B). So, you best be mindful of how long you have your mixed epoxy in the mixing container, or else it will gel and become hard to move before you even have it poured! However, a possible work-around would be using Table Top Epoxy in colder ambient temperatures as this would slow the chemical reaction and generation of heat.
- For reference, working time can also be called “pot time” or even “gel time”, because it refers to the amount of time you have to work with the liquid epoxy in the mixing container – or pot – before it gels, a first stage of hardening.
Pour Depth (Intended Maximum):
– Casting Resin is used for making casts with molds. This sometimes requires a deep pour. Because of Casting Resin’s thin viscosity, it is able to be poured quite a few inches deep because it won’t generate too much heat. It is in this ability that some experienced epoxy artists use Casting Resin for pouring fewer, thicker layers for projects like river tables and decorative bar tops with encased items.
– Table Top Epoxy is used for coating flat surfaces like table tops, countertops, and bar tops. Because of Table Top Epoxy’s thick viscosity, it should be poured in thin, individual layers between ⅛ and ¼ inches. Table Top Epoxy should never be poured in thicker layers than what is recommended in the instructions, or else the thick epoxy can overheat and cause imperfections.
- Important Note: Let each layer sit for 4 hours – no more than 10. This timing ensures that this previous layer will be cured enough to set the layer, but still chemically soft enough to bond with the next layer.
Mix Ratios:
– Casting Resin typically has a small, simplified ratio, like 3 or 2 to 1. This means that when mixing, you’ll use 3 times as much of part A, as you will of part B. But the simplicity of the ratio allows you to decide the volume without a lot of complicated math (for example: a 3:1 ratio could be 15 ounces of part A and 5 ounces of part B.)
– Table Top Epoxy typically comes in the easiest ratio, 1:1. This means that you will use equal amounts of both part A and B (for example: 15 ounces of part A and 15 ounces of part B.)
- All ratios vary by manufacturer, but both systems are available in simple ratios like 1:1. However, you must always follow the instructions and measure each part accordingly using labeled containers. Inaccurate measurements will definitely result in imperfections and/or epoxy that will not cure at all.
Other Notable Differences:
– Casting Resin is usually a thinner viscosity, and so it allows bubbles to escape easier. However, because Table Top Epoxy has a thicker viscosity, it is less likely to form bubbles when both mixed and poured steadily and slowly. Keep in mind this careful preparation method is still highly recommended for all projects.
– Table Top Epoxy usually has a better ability to withstand scratches. This makes it more suitable for coating projects like desktops and countertops that will get the most physical contact.
Other Notable Commonalities:
– Both can be UV Resistant. This means the system was manufactured by design to resist the harmful and inescapable uv rays of the sun. The effects of which would become more visible as time passes. However, most manufactures will instruct you to keep your epoxy resin projects away from prolonged direct sun exposure regardless of their claimed resistance.
– Both can be heat sensitive. Epoxy resins designed to withstand very high heat are typically expensive – more so than the small scale systems used for DIY projects. This being said, most small scale systems will produce cured epoxy that will begin to soften and lose shape at temperatures as low as 120-150 degrees. Be sure to read manufacturers notes when considering an epoxy resin for a project that will be used in contact with heat (for example: coasters, dinnerware, table tops, hot beverage containers.)
Biggest Variables for Human Error:
Guidelines to help achieve your epoxy resin goals every time:
- Follow the instructions. Read them multiple times so you have absolutely no doubt about what you’re doing. Intentional or not, deviating from instructions is the most common cause for imperfections. Not all instructions across all brands are the same, keep this in mind. Because of this, you also shouldn’t mix brands.
- Use accurate measurements. Making that perfect ratio of part A resin to part B hardener is the first step. Get this wrong, and the project will fail, even if you do everything else perfect.
- Mix thoroughly. Even if your measurements of added part A and B are correct, they still have to be mixed correctly in order to work properly. In every drop, there must be an accurate ratio. Use a flat mixing stick to better scrape the sides, bottom, and edges of the mixing container or bucket. Try to minimize the amount of air you incorporate, as well.
- Only prepare what you need to use, when you’re ready to use it. Don’t prepare your epoxy resin mixture until you’re ready to pour your project! Once mixed, the chemical reaction will start and so too will your resin start to harden. Don’t mix too early or your resin will harden before you even pour it!
- Before pouring, always level your piece. This ensures reliable, even results.
- Pour thinner layers. You’re sure to have learned by now that epoxy is a temperamental thing. While this means increasing the number of pours, it also means greatly reducing the risk of a thick layer overheating and forming imperfections. We say the extra effort is worth it.
- Slightly reduce the temperature of the working environment. Epoxy is meant to be poured at about room temperature, and we don’t recommend lowering it below 65 degrees. However, whatever the temperature, do your best to keep it stable and consistent. Temperature fluctuations disrupt the temperamental curing process and can leave imperfections like uneven dimples or cracks.
- Use clean supplies. Make sure everything is clean and dry. Any dirt or water will contaminate and disrupt the curing process, leaving imperfections.
- Use a short and wide cylindrical container for preparing the resin and hardener, this makes thorough mixing easier and reduces the heat build up in epoxy. This is in substitute to a taller, narrower, cylindrical container.
- With the perfectly smooth finish in mind, be sure to cover your piece. Find a way to prevent dust and debris from contaminating the epoxy surface during working and curing.
- Use Deep Pour coating Epoxy for layers. This will help avoid layers overheating when accidentally poured too thick.
Recommended Supplies:
Time to take what you’ve learned and get to work. Our goal with this article is to have empowered with the information to go forward and get creative with your epoxy. To make choosing supplies a little easier, we compiled some of the top rated online options.
Here are the popular picks for some of this article’s items:
- [link – mixing container]
- [link – mixing stick]
- [link – top rated table top epoxy beginner’s kit]
- [link – top rated deep pour epoxy]
… etc
