Introduction: Epoxy Coasters
Have you ever stumbled across some coasters and wanted to keep them either because they were amazing or as a souvenir, yet once you get them you can't use them or show them off because of how fragile they are? Well in this Instructable I will show you how I've been preserving my coasters.
This process should take about a week to do, with the biggest time consumers being waiting for things such as epoxy and polyurethane to dry. It should cost (assuming you already have the tools) about 65 dollars to do 10 coasters, and after that the biggest cost will be the epoxy which is about 30 dollars for easily 15 coasters.
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Step 1: Tools and Materials
For this project you will need the following tools:
note that the end goal is cutting the right sized frame and cutting out the middle for the coaster, feel free to swap tools as are available, but this is what I used so your results may vary based on what you use.
Saw: This is used to cut the wood into the right size for the coasters.
Hand drill: This is used to cut out a hole for the jig saw to be able to cut out the middle of the frame.
Jig Saw: This is used to cut out the middle of the frame.
Dremel: This is used in the router table for sanding the frame and sanding any issues with epoxy.
Dremel router table: This is used to sand away the edges inside the frame so the coaster fits in smoothly. I highly recommend getting one of these because using a Dremel on its own is a pain due to it needing to be on a level surface.
Clamps: To keep the frame from moving around when using the jig saw, Dremel, etc.
Sand paper: Used to sand the wood before applying polyurethane as well as helping sand any epoxy issues. I recommend for the wood going from 60 grit to 200grit so it's smooth and the polyurethane applies easily. For sanding epoxy make sure you are using higher grit (up to about 350 or so) based on what I've read on Epoxyworks.com.
Precision knife: Good precision knives to easily and effectively cut the masking tape. I highly recommend these over a scissors for more precise cutting.
Please note that when working with epoxy, almost everything is 1 time use (cups, gloves, brushes, etc) with that in mind DO NOT GO CHEAP (IE Walmart). This will result in issues and headaches down the road. The cost of buying 25 cent brushes vs 18 cent ones is worth it when your brushes don't fall apart and leave bits of brush all over your project.
Epoxy: I highly recommend going with Alumilite Epoxy because of it's cost as well as the fact that when doing smaller mixes (around 1oz) it doesn't lead to issues. My first batch with a different bulk product resulted in a lot of issues with the epoxy sticking, not curing, etc.
Isopropyl Alcohol: This is used to lightly mist the epoxy to help get rid of air bubbles.
Spray bottle: This is used for the isopropyl alcohol to lightly mist the drying epoxy to help get rid of air bubbles, make sure to get a good bottle that can evenly mist your coasters.
Wood: I recommend the Menards 6mm craft plywood because they have a 3mm version so if you want to do a coaster with a solid wood back, they won't be different sizes. I recommend the 6mm size because its a very good ratio of wood to coaster that doesn't make these look bulky.
Masking tape: Get a good brand that will resist the epoxies ability to seep into it, as well as matching the look of your wood in case some gets stuck under the epoxy.
Brushes: Small foam brushes are great, and you will need about 8 of them from start to finish.
Polyurethane: I went with a clear gloss oil-based polyurethane.
Parchment paper: This is wonderful because the epoxy, polyurethane and Mod Podge does not stick to it so if any leaks your projects, and your work space will be safe and your project won't have residue stuck to it from rags, newspaper, etc.
Disposable cups: I used solo cups (and the shots version of them) for measuring and mixing because of their cost, and because the lines were great for measuring the epoxy.
Disposable gloves: makes everything much easier and safer, from Mod Podge to epoxy.
Stirring sticks: I recommend using popsicle sticks because they are cheap, and can be used for the supports, stirring and applying the epoxy.
Mod Podge: Used to preserve the coasters and prevent the epoxy from discoloring them.
Coasters: A very important part of this project, make sure they aren't damaged or in bad condition. Never been to a place where they won't (when asked) give you a few for free.
Step 2: Coasters and Cutting Wood.
For getting the coasters I recommend going to the craft breweries, they almost always have their own coasters that are cool and unique. For your first few coasters you make I recommend getting duplicates so if you make a mistake, you aren't ruining a unique coaster, but at the same time you aren't wasting your time preserving a generic coaster. Also make sure you get a "new" one, not one that's been used. As you can see from the Junkyard coaster I got above, there's some discoloration from water. I also recommend if you do this, to do at least 5 so you aren't wasting epoxy and time.
After you've bought the wood you want it's time to measure and cut it. For my coasters I wanted their final size to be 4 1/2 by 4 1/2, so I cut at 4 3/4 since the plywood (as pictured above) tends to splinter and you need to sand those sections off.
The splintering only happens when you are cutting against the grain, so feel free to get closer on the ones that are with the grain, however a little extra time sanding is a small price to pay for smooth edges.
Once you have the wood cut and sanded to the right size it's time to measure and cut out the inside of the frame. Very important here that if you are using square coasters to use the actual coaster you plan on using for the measuring because (as seen above with square coasters) there is slight differences in the corners on some square coasters. For measuring the coasters on the frame I had about 3/8 in on each side, but this will vary based on your sanding, the important thing is that the coaster is evenly spaced on the frame.
Once you have the coasters measurements it's time to break out the drill and cut a hole for the jigsaw. When doing your hole get it close to the edge but give yourself some space because the wood loves to splinter on this part as seen above.
After you've drilled your hole, use the jigsaw to cut out the rest of the inside, don't worry too much about being on the line, give yourself room because the Dremel is where we get the precise work done.
After you've used cut out the middle, use the Dremel routing table to carefully sand away the last bits so you can put your coaster inside the frame. It's important that the coaster can slip into the frame without too many issues, you want it to have a little resistance in some areas but not so much that you are forcing it in.
Note: if you've got any chunks missing, use dust from earlier (there will be plenty!) and glue to fill in these gaps.
If you are doing a solid wood backed frame instead of a open backed one, it's at this point you would glue the pieces together and wait overnight, then resume below.
Now lightly sand the frame to remove any pencil marks, flaws and smooth out the surface, I went from 60 grit to 200 grit doing this, sanding away as little as possible since there isn't much to work with here. The goal is the frame is smooth.
After the frame is smooth, lay down a sheet of parchment paper big enough for all of the frames. Now it's time to apply 2 light, even coats of the polyurethane. This is to prevent the epoxy from seeping into the wood and discoloring it, as pictured above. This is also because once you put the epoxy on, you can't go back and do the inside of the frame so it's important it matches.
Step 3: Preparing the Coasters
While your frames are drying, it's time to prepare the coasters. Lay out your parchment paper so that all of your coasters can easily fit on it and, using a small foam brush, paint the coasters with the Mod Podge.
Be sure to do at least 3 layers of Mod Podge on both sides of the coasters, as well as the edges. when you are applying Mod Podge to the edges of the coaster,, do not spin the coaster between your fingers, I've done this and it resulted in the coaster ripping. The best way to the edges is to hold it with 2 fingers and lightly dab the edges with a brush, then transfer the coaster your other hand to get the rest of the edges. To see if you did the Mod Podge correctly, hold the coaster up to a light and the entire surface is shiny, any dull areas indicates a lack of Mod Podge.
If you don't cover the coasters enough the epoxy will seep into the coaster and discolor it. The Junkyard coaster above is a comparison between an original coaster, no Mod Podge and only 1 coat of Mod Podge. You can clearly see the discolored spots. You can also see it on the coaster I ripped.
Thankfully the Mod Podge dries quickly (about 10 min) so if you are doing a large batch you should be able to just keep going since by the time the last one is done, the first one should be dried. You can re-use your brushes with the Mod Podge as many times as you like since it is easy to clean off of it provided you don't let it dry.
Step 4: Sealing the Coaster Edges
Now that you've got your coasters covered in Mod Podge and your frames have 2 coats of polyurethane, it's time to begin taping and sealing.
Apple a single layer of tape to the top and bottom of the coaster. When you do this you should have enough excess to fold over and cover the edges, but it's very important that the surface of your frame remains flat or the epoxy will not be level.
Once you have the frames taped up it's time to cut your parchment paper for them to rest on. I recommend cutting a piece of parchment paper an inch bigger than the frame so that you can easily move each individual frame around without lifting it.
Once you have the frames laid down on the parchment paper it's time to apply the supporting material. The supporting material is something that will prevent the coaster from sagging or being pushed out of shape when you apply the epoxy. I used popsicle sticks and just laid them in a pattern that wasnt too close to the edges of the frame (to prevent any leaking epoxy from sticking to it) yet was close enough to stop any sagging from occurring.
Once you have the frames taped, the parchment paper ready and the supports laid out it's time to insert the coasters. These should go in relatively smoothly with minimal force required but some is fine and to be expected.
For sealing up the inside of the frame and coasters its time to do a little epoxy work. Mix up a small amount of epoxy and once it's ready lightly dip your popsicle stick into it.
You want enough to form a drop but not enough for it to fall off on its own. Then dab that drop near the edge of your coaster and gently push it towards the edge, forming a bridge over the gap between the coaster and the frame. This part is pretty easy once you get the hang of it, the goal is not to rush, but to be steady. For coasters that don't fit the frame very well (as seen above) I recommend doing these near the end when the epoxy starts to harden more. If you cant form that bridge don't worry, just get some on the frame and the coaster, then once its dried, flip it over and do it on the other side.
Once your done sealing the edges, inspect them for air bubbles. Given how small the amount of epoxy you applied was there shouldn't be any but if there is (and assuming about 10 minutes have passed) lightly mist the epoxy with your isopropyl alcohol. Epoxy is great at self leveling and getting rid of air bubbles, so don't worry too much about this.
Step 5: Inspecting and Pouring
After your epoxy has cured for about a day it's time to inspect for mistakes and pour the first half of the coaster.
First inspect the underside of your seal for any leaks, this happens and isn't a big deal since you were using small amounts, the parchment paper will prevent it from sticking to the table and the masking tape will prevent it from sticking to the frame. Some of these can be pulled off (as seen above) while others will require a little love from the Dremel (next step for more of that).
I would highly recommend repeating the sealing process in step 4 to prevent issues like what happens in step 6 (spoilers!).
Before you begin pouring make sure that the seal is good. Visually and physically inspect the seal to ensure that there is no gaps (the reflections from a light work wonders for this). Also make sure that your surface is level, and that the frames themselves are level, epoxy is a self leveling substance so if the surface isn't level, you'll find out the next morning, as show above.
When it comes to pouring do the side you applied the seal to first. The reason for this is that if there are any issues (such as parts that need to be Dremel'd off) or you didn't seal any parts, you wouldn't be affecting the part that is done correctly.
For the epoxy I recommend doing no more than 5 coasters worth per mix. This prevents you from feeling rushed by the epoxy drying and prevents too much from pouring out at once.
When pouring, start in the middle, pour a bit and use your stirring stick to spread it out. Often times I ended up pouring too much and needed to spoon it back into the cup. The best way to see if you poured too much epoxy is to get eye level with your coaster and see if it's raised up above the tape.
Once you've poured all of your epoxy, after 10 minutes or so, lightly mist them with the isopropyl alcohol, this will help with air bubbles.
Step 6: Screwing Up
Now that you've poured your epoxy, it's time deal with all of the wonderful mistakes.
For coasters with gaps in the Mod Podge there's really nothing you can do, you might as well turn these coasters into experimental coasters for trying new things, but for the leaks in the seals or drips we can fix those.
For the drips in the seals and leaks, you can easily sand them off. If you sand off the entire layer and do a full coat you will be fine, but as seen in the red coaster, if you just try to "patch" the epoxy, it will look pretty bad. You can also do this for the uneven coasters such as the Junkyard one.
For sanding epoxy the first thing you need to do is get the surface damp. This will prevent the dust from getting into the air and will instead just go on your workbench and hands (wear gloves!). Do this in small amounts, keeping the epoxy wet and making sure to not hit the frame, just the epoxy. Also avoid angling the Dremel too much or you risk breaking the sanding band which can cause injuries.
Once you've ground the epoxy down to where you can apply epoxy over it you need to sand it so it's smooth. Get the epoxy damp and begin sanding, starting with around 60 grit and working your way up to 350 or higher. you want it as smooth as possible so there is no open pockets for air or dust to get trapped in.. Be very thorough on dust removal, use brushes, vacuum, etc since the dust is what will stand on the most when you reapply the epoxy.
Step 7: The Next Layer
Now that you've fixed any issues with the other side of the coasters, it's time for the final layer. Just like before make your epoxy and pour it onto the coasters, making sure to spread it out and avoid pouring too much. The coaster above is the one with the massive leak with epoxy just applied to it, see how invisible it is? It gets even less noticeable as it dries.
Step 8: Polyurethane
Now that you've got epoxy on both sides of the coaster, it's time to apply the final coats of polyurethane.
Remove as much of the tape as possible with your fingernails. Be VERY careful if you decide to use the precision knife here as it can easily scratch the epoxy. This is why you use tape that matches your wood, in the event that some is trapped under the epoxy it will blend in very well.
Once you've removed all of the tape it's time to apply the polyurethane all over the coaster including the epoxied part. Apply a heavy coat and using a light, find the lines (as seen above) and apply more polyurethane to these areas until they are gone. Let it dry and do another coat, 2 per side. This is dont to prevent it from sticking to things like beer bottles or coffee cups. Currently the best solution I have.
Note: I tried using spray lacquer instead of polyurethane and it resulted in a cloudy look and was very sticky, do not use spray lacquer.
Step 9: Testing and Improving
Now that you've got your first batch done it's time to test them out! Using a variety of containers, (cans, bottles, coffee mugs) ensure that they function as designed, be sure to thoroughly test them! They should have some stickiness to them to prevent beverages from sliding off, as well as to prevent them from sliding around tables, bar tops, etc.
Enjoy and please leave any comments or suggestions!
This is the third version of this project I've done, and a lot has been solved but there are a few known issues that, when I have time, I will get around to fixing.
Known issues with this version: Hot liquids such as coffee can cause these to slightly stick to the containers.
These also tend to stick to each other a bit if they are left in a pile for a few days. (version 2 was terrible in this regard, they were almost impossible to separate).
Finally, with hot liquids such as coffee, the coaster releases a slight woody smell, though it isn't sticky or wet because of it, and it doesn't damage them at all.
As mentioned above, this is the third revision of this process, version one (pictured with the can) was a quick 3 day build with minimal sealing and cheap tube epoxy, I also sanded the surface down which I found out doesn't work out well.
The second version (the 10 shown above) was a much more improved but also MUCH more time consuming process, as I wouldn't seal the coasters, but instead I would clamp the frame down, pour in some epoxy, then put the coaster on top. This resulted in plenty of bubbles as well as an uneven surface on the clamped side where I would have to do another layer of epoxy over that. These coasters also had a horrible tendency to stick to each other so tightly that I feared damaging them by prying them apart. This version also took about 3 months to make 10 since I was limited by the number of clamps and I had to do at least 3 epoxy pours.
The current version, version 3 (the 9 in a neat square) is a much more improved version taking significantly less time to make and doesn't stick nearly as much as version 2.
Version 4 should (hopefully during winter break) be made with better wood, and deal with the stickiness of the coasters though it's a minor issue.