Epoxy is a type of adhesive that is made up of polyamine hardener and polyether resin. It was discovered by chance in 1936 by a chemist named Harry Coover.
It is most often used for woodworking and repair. Epoxy sets hard within 24 hours, has a high resistance to heat, can be sanded or drilled into, and it makes for an excellent adhesion between two different surfaces.
Types of Epoxy
Epoxy comes in two parts: the resin (A) and the hardener (B).
The resin is typically clear or amber in color, while the hardener may vary from clear to dark yellow or brown.
How does epoxy work?
Epoxies are usually supplied in equal parts as A and B components are mixed together at a mixing ratio typically stated as either 1:1 (by volume) or 2:1 (by volume), which means that the mix ratio varies depending on which type you have chosen. This mixture needs to be done carefully—if too much A gets added to the mixture, it will not set correctly!
Can you 2 part epoxy over 1 part epoxy?
There has been quite a bit of disagreement over whether or not you can apply 2 part epoxy over 1 part epoxy.
It is also more resistant to damage from UV light, which can really help your project stand up against the elements.
That being said, there are some downsides to using 2 part epoxy vs 1 part that might make it impractical for certain applications:
- It’s harder and more time sensitive to apply (mixing ratios need to be exact)
- It’s usually more expensive
Table of Contents
Can you 2 part epoxy over one part epoxy?
When trying to decide whether or not you can 2 part epoxy over one part epoxy, there are a few things to keep in mind.
1: You will need to sand the original one part epoxy down to give the new two part epoxy a rough surface to bond to.
2: Clean the surface with acetone and let it dry.
3: Use two part epoxy that is rated for marine use in order for it to have a high enough chemical resistance rating so that it won’t be damaged if your project comes into contact with water or ice.
Can I put epoxy over epoxy?
The short answer to this question is a resounding yes. Generally, you don’t need to worry about whether the epoxy you’re putting down on top of another layer of epoxy is 1 part or 2 part as long as you follow the 24-hour rule.
However, if you are working with multiple layers of epoxy and more than one has cured for longer than a day, it’s best to sand off the outer layer before applying your next coat.
This helps ensure that the epoxy bonds uniformly, which could save you from having an uneven surface once everything has been set completely.
If you are trying to fill a gap or create a seal between two materials using several coats of epoxy (or epoxy mixed with filler), you will probably want to use an epoxy that doesn’t sag too much when applied in thick layers so it doesn’t drip down or run off before hardening.
Is 1 part or 2 part epoxy better?
1 Part Epoxy
In general, it is better suited for smaller projects that don’t require a large surface area to be covered.
2 Part Epoxy
2 part epoxies cure faster than 1 parts and are ideal for larger repairs on fiberglass and plastic surfaces. They are also good for bonding dissimilar surfaces like metals, ceramics, and glass.
If you’re repairing something larger or creating an art project that requires a lot of coverage, then 2 parts are the way to go!
What is the difference between 1 part and 2 part epoxy?
If you’re looking for the most reliable, long-lasting coating to use for your woodworking or DIY project, a 2 part epoxy resin is your best bet.
The epoxy molecules in 2 part epoxies are chemically bonded so that when you mix the two components together and apply them to your project surface, the epoxy resin hardens into a thick, clear protective layer. This results in a stronger and more durable coating than 1 part epoxies.
2 part epoxies consist of an epoxy resin and a hardener that you mix together before applying it to your surface (check out our guide here).
After mixing the two parts together, they form a chemical reaction to generate heat and allow the substance to cure.
This curing process forms strong bonds between molecules which produce a thicker coating. Although 1 part epoxy resins can be used as coatings too, they don’t form as thick of material and won’t create as strong of bonds as a 2 part system would.
2 part epoxies can also be made with pigment added to them so that they will cure into different colors (check out our guide here).
These color pigments will not alter or change the properties of the high-quality epoxy resin formula that makes 2 part systems so effective.
Should you sand between coats of epoxy?
No. You do not need to sand between coats of epoxy, regardless of the brand or type you’re using. However, you may wish to sand the first coat (or two) for a variety of reasons.
First Things First: Why You Don’t Need to Sand Between Coats
Most epoxies are self-leveling because they consist of a resin and a hardener combined in specific proportions. That said, there are exceptions—some DIY epoxies don’t have this property and need to be applied evenly with a squeegee in order to achieve an even finish, while others set incredibly fast and require that you work quickly with whatever tools you’re using (brushes, rollers) in order to avoid brush marks, ridges or imperfections.
So why is it so important that your epoxy self level? Well, if your epoxy doesn’t level itself out once it’s been applied and left alone for about three minutes after application (a process called “flow out”), then you’ll find yourself spending hours trying to sand away small inconsistencies by hand.
Not only does this take a long time but it’s physically taxing as well—epoxy grinds away at your paper much faster than wood does!
While some products like Super Glaze boast incredible flow-out properties and seem almost like honey when poured on its surface, other materials might require multiple layers before the final result is smooth enough for users’ liking.
If you’re stressed about how thick each layer should be or worried that applying too much will cause a big mess during the curing phase, then check out our article on how thick should an epoxy coating be? It will give more tips!
Can you sand epoxy and recoat?
Epoxy resin is a two part product that consists of a resin and a hardener. Like most resins, there are many different grades of epoxy resin that offer varying features and benefits.
This can include things like UV resistance, scratch resistance, heat resistance, etc. The best way to determine if your particular resin is sandable is to read the datasheet supplied by the manufacturer or speak with someone at your local hardware store.
If you are using art resin specifically (which we do not recommend for woodworking) then you should be able to sand it down enough to recoat it.
If you’re using polyurethane or epoxy floor coating on top of epoxy then you may run into complications as these products tend to lift off of the surface if they haven’t fully cured yet (which can take up to two weeks).
So, can you 2 part epoxy over 1 part epoxy?
Well, we just told you that you could. You can use 2 parts epoxy over one-part epoxy. Never do the opposite, though.