Last time I was making frag plugs using sand molds and cement. I have changed things to use clay and silicone molds and will discuss my methods here.
Last post I talked about how to make a silicone mold. You can find that here if you missed it. Those silicone molds work great for cement or, as I’ll show here, clay.
There are a bunch of options on today’s market for clay. You can find air dried, low fire, high fire, earthenware, stoneware, even porcelain clay. While you typically want to avoid the air dried clay, as most are not actual clay, some labelled as air dried are actually low firing clay. These can work for our purpose as long as they can be fired. If you have a local college nearby, check if they have a craft shop. My local university sells 25 pounds of clay at only $15! You can also look at nearby craft shops or on amazon. I will say amazon is about the worst price per pound with clay but if you only need a small amount, that is probably your best bet.
Making the frag plugs
Using our set up silicone molds to make the actual plugs is really easy. Start by grabbing a small amount of clay out of the bag.
Start by taking a piece and rolling it into a ball. Next, take that ball of clay and roll it between your fingers to produce something that looks like a short piece of rope. In pottery this is called a coil.
Take that coil of clay and put it all the way into the bottom of the frag plug. Initially I added small bits of clay into the hole but found I was getting inconsistent results with getting a nice base for my plug. I started this method and have had great success.
Once that coil is in the hole, just push it down with your fingers. Make sure to really push into the hole as we want the clay to get in and really squeeze into the mold. If you hear a popping sound that is good! That means an air bubble has popped and escaped the clay which is what we want. Air bubbles in the clay can lead to breakage when we go to fire it.
After the hole is all filled it, the rest is even easier. Just take small bits of clay and push on it to fill the rest of the mold. Try to be careful and keep the clay level across the top or you could end up with a lopsided product. Once it is all full your done with that mold! Continue with the other plugs if your overall mold has more than one plug in it.
The drying stage
This next step is a long one. You have to let the pottery dry a bit before we can shape the plug to remove any defects. You have a few options here. The first is to leave the clay in the mold for 10-12 hours and let it turn into a leather hard stage. The second option is to stick the molds in the freezer for 30-60 minutes. My small frag plugs freeze in about 30 but the larger plugs take a good 50-60 minutes to freeze through. If you have a day you want to make a large amount of plugs, freezing is your best bet. Simple place in the freezer and pull it out once it feels rock hard.
Once your clay feels hard to the touch, whether by air drying or freezing, simply pop the clay out of the mold. You’ll notice lots of imperfections here and that is OK. We will have time to fix them later. If you went with the freezer method, be quick about taking the plugs out of the mold. They thaw again in minutes and once they thaw you have no chance of removing them in one piece. Simply place these plugs on a table or counter to thaw and let them dry out naturally. They will be quite sticky once they thaw but after drying a little they will not stick to the table anymore. Put them somewhere that they can be left undisturbed for at least the rest of the day, even possibly overnight.
Once your clay is leather hard (hard to the touch but not bone dry where all the moisture is gone) we can shape the clay to remove those imperfections. I started with using a wood chisel but upgraded to an actual pottery carving kit I bought on Amazon for cheap. I like to put the chisel or other sharp tool against the side of the frag plug and twist the frag plug around in a circle. This gets all the excess from the top of the mold off and creates a nice smooth edge around the outside. You don’t have to do this step but where I will be selling these frag plugs with corals on them, I want them to look nice. I also make sure my top is mostly even and straight and make sure I don’t have defects on the bottom that will cause it to not sit in eggcrate.
That’s really all there is to it. Now we just let the plugs dry before we fire them. Once again we have two options – let them air dry over the course of several days or we can bake them in the oven. If you choose the oven, set the temp to 190-195 and let the plugs sit there for an hour or two. I chose that temperature because water turns to steam above 200 degrees, I believe it’s 212 actually, and we don’t want steam. Steam will cause our pottery pieces to break or even explode. So we set the temperature lower and then the moisture just bakes right out of the clay.
Firing – the final step
I sort of lied here. It’s the final step to making our frag plugs but there is another step after where we check them. Firing is important because if we don’t fire it, the clay stays as clay and will rapidly fall apart in the water. When we fire clay we turn it into pottery which will not fall apart on us when it absorbs water.
As always we have a couple of options here. The first option is the use of a kiln to have our clay fired in a controlled environment. This is the safest method to keep all your precious pieces getting to the correct temperature. If you have a local college where you bought the clay, you can bet they have a way to fire it too. My university doesn’t charge me for the first firing if I buy the clay from them. If I buy clay elsewhere they charge 50 cents per item to fire. Not bad if I were only making a few plugs but I want to make hundreds.
The other option we have is to pit fire our clay. This is the oldest tradition of creating pottery and we can replicate it in our back yards. I use a portable fire pit that we own to do my own pit firing. Traditionally a hole is dug in the ground for the pit. It’s winter right now where I live so I am not about to dig a hole anytime soon. I’ll have another article all about how to pit fire your pottery so I won’t get into too many details here.
Now that we have fired our clay it is time to do a water check. Simply place your new pottery in a bowl and cover them with water! Let it sit for around half an hour. It will be pretty easy to tell the pieces that fired fully vs those that did not. The ones that did not fire all the way will rapidly fall apart in the water while the actual pottery remains intact and feels rock hard after a soak. I like to squeeze with my fingers as well to make sure it feels rock hard and doesn’t break easily. The water bath is also important because it helps remove any harmful chemicals that may cling to the pottery to be removed.
Don’t worry if your pottery broke apart. As long as it fired the right way the pieces are still useful. The tops can just be a frag disk now and the bottoms make for excellent media for bacteria to grow in. Just throw into your sump and forget about it.
That is the whole process! Next up I will talk about how to pit fire your own pottery if you so choose. If you have been using this as a model for making your own frag plugs, comment below your success!