I have a minor obsession with Pinterest, so after seeing a set of bottle cap coasters that looked like they might scratch the table, I said, "I can do that better!" Well, with a little help from the recipient of this gift and a couple failed attempts at other options, I chose resin casting to make these super awesome coasters. A great way to show the man in your life that you care, these fun coasters are easy to complete, done in about 4 days (assuming you only have 1 mold) and don't take that much active time on your part.
Step 1: Materials List
What you'll need:
Plastic or plastic coated cups to mix in
Something disposable to mix with (I used popsicle sticks)
A well ventilated area
Bottle caps to set in the resin
If you want your coasters to be colored, you can get resin dyes as well.
Links above are just some places that I have found these items, not necessarily where I got them from.
Step 2: Get a Mold and Prep It
There are two different options here, you can find a mold online or you can make one yourself. If you buy one, make sure that it's specifically for resin. This is important because if you use the wrong type of mold, you may never get your coasters out. If you want to make the mold yourself, you can use whatever type of mold material that you're used to, so long as it's usable for resin. I was lucky enough to convince my father to make a mold for me using this stuff. I asked him to make a 3.5"x3.5" mold which fit nine bottle caps pretty perfectly. I won't go in to how to make the mold because I don't really know how to.
To prep your mold, spray a thin coat of mold release on your mold. Let it dry before casting your resin.
Step 3: Prep Your Bottle Caps
If your mold is clear, you can place your bottle caps upside-down during the next step and skip this step. Because my mold is extremely opaque, though, it would have been impossible to see the positioning of the bottle caps from the bottom side of the mold. Because of this, I had to set the bottle caps right-side-up rather than upside-down. If you try to do this without prepping the bottle caps slightly, they will float and casting these will be much harder. To prep the bottle caps, I turned them over and filled them all with resin. Approximately 1 oz of resin was enough to fill nine bottle caps. By doing this, you ensure that you won't get your bottle caps floating to the top of the coasters. Let these set for about 10-20 minutes before moving on to the next step.
Step 4: Pour the First Layer of Resin
Now it's time for us to start the actual casting. Mix about an ounce of resin using the manufacturer's instruction for multilayer casting. The stuff I used said to add 5 drops of catalyst for every ounce of resin for the first layer, so that's what I did. When mixing the resin, you will get a lot of bubbles. I read a lot on the internet about using a blow torch or a straw to get out all of the bubbles. I found that the best way to do this was to let the resin sit for about 5 minutes. This lets the bubbles collect toward the center of the mold and then I grabbed a mechanical pencil, pushed the lead out about 1/4", and moved all the bubbles in to the center of the mold. I gave it another 5 minutes for the bubbles become one big bubble and then popped it with the pencil lead. Before moving on to the next step, wait about 20 minutes from the time that you initially poured this layer of resin.
Step 5: Insert Your Bottle Caps and Pour the Top Layer of Resin
Flip your bottle caps over and place them in the resin. The bottom layer of resin will be a little sticky now, so be careful of how you place them. Place them in the exact places that you want them. After you're done placing the bottle caps, mix another 1.5 oz of resin using a lower amount of catalyst per ounce. I used approximately 3 drops per ounce, so a total of 5 drops for the 1.5 oz. The less catalyst you use, the easier it will be to remove the bubbles. Pour this mixed resin over the bottle caps ensuring that you've covered all of your bottle caps. If you haven't, just mix up some more and add it to the top. Use the same technique you used in the last step to get the bubbles out of the resin. Leave this sitting in the mold at least over night. The resin will not be hard enough to use as a coaster for about 2 days.
Step 6: Finishing Your Coasters
This is a new step as of 4/25/12. I had been asked about how to finish the coasters, so I'll tell you exactly how to do it. The only thing you need that isn't on the original materials list is sand paper and an object to elevate the coaster (see picture picture). The sand paper should be no coarser than 200 grit and the object should be at least an inch high tall and small enough that all 4 edges of your coaster can hang over the sides after being placed on top of them.
To make your coasters smooth, use your sandpaper to remove any bubbles or imperfections (aka the meniscus that has formed around the top rim of the coaster) that may have appeared during the initial pouring. I used 220 grit sand paper. It's not extremely important what grit you use, but I wouldn't go any courser than a 200 grit. All you want is to remove the bubbles and not make scratches that are too deep. Once you've sanded the bubbles and imperfections out, wash the coaster in water to remove all of the resin dust. Make sure that it's clean. The dust left on the coaster will get embedded in to the coaster after you put the next layer of resin on and will make this step useless. After completely drying the coasters, place some paper on your work surface to keep it clean. On top of the paper, place your coaster on top of the object mentioned earlier (see picture again). Mix up another ounce of resin using about double the catalyst that you used for the base layer of the coaster (I used 10 drops of catalyst for 1 oz of resin). Pour a thin layer on top of the coaster. You can smooth it out to the edges using your stirrer. Once you've made a nice coat on top, coat the sides by using your stirrer to place the resin on the sides of the coaster. It will drip, which is why you covered your work surface and used something to elevate the coasters. After about 5 minutes, use a popsicle stick or anything else that you can throw away to remove the beads of resin that have pooled on the underside of the coaster on each of the 4 sides. You now have removed most of your imperfections. Pictures 4 and 5 of this step show bubbles on the side of the stone coaster and their appearance after the first coat of finishing resin. It's likely that I will have to repeat this step (at least for that coaster), but it's definitely an major improvement.
Step 7: Enjoy Your New Coasters
Now you have a super awesome coaster! If you're still worried about it scratching your table, you can go out and buy silicon pads at Home Depot for the bottom of the coasters. They're super cheap and clear, so you should not see them after you put them on the bottom of the coaster.
Thanks for reading!