Science In Your Hands!

Plaster and Tile Tool Guide

A plaster and tile tool is a great alternative to using a glass grinding tool. They generally decrease the amount on time and grit used during grinding. Making one is very simple and the materials needed are fairly easy to find at your local hardware store. However you can save yourself some time and money by purchasing one of our Plaster and Tile Tool Kits. Here are detailed instructions for making your plaster and tile tool.

Plaster Disk MoldStep 1. Build a dam for your plaster disk

You will need to construct a dam that wraps around your mirror blank that is twice as tall. Eventually you will put this dam around the blank and pour the plaster on top. The dam creates a mold that will create a plaster disk that has the same dimensions as your mirror blank.

Your dam can be easily constructed from an old cereal box or posterboard. If you want to make one that can be used multiple times you may consider a more durable material. We have used things such as "for sale signs" for mirrors up to 6 inches in diameter or even better, those flexible cutting boards made from plastic. The cutting boards will have to been made in a number of sections since they are general not long enough to go all around the mirror's circumference.

From your cereal box or other material cut our a long strip that is twice the thickness of your mirror blank and at least as long as your mirror's circumference (3.14 x diameter). You will then tape the ends together into a circle.

Step 2. Prepare your mold
Now that you have constructed your mold you can prepare your mold for casting. Set you mirror blank on a flat and level surface. If you mirror blank is not level your plaster disk could have one side thicker than the other. Next, take a piece of plaster wrap and stretch it over your mirror blank so that you have as few wrinkles in the plastic as possible. This will ensure a nice flat surface on your plaster disk. Now take your dam and slide it over your mirror. It should have a nice snug fit. If you need to retape the dam so that it fits tighter this is okay. The ends of the dam can overlap without any problem. It may leave a bump on the side of your disk but you can sand it down later if you want. If you still have some wrinkles in your plastic wrap you can usually stretch it out a little even with the dam overtop to get rid of them.

Step 3. Mix and pour plaster
With your mold set up you can now mix your plaster. You will want to mix 2 portions plaster of paris with 1 portion cold water. Measure these by volume. Your mix will start out lumpy and get nice and smooth when it is ready to pour.

Lumpy PlasterSmoothly Mixed Plaster
lumpy plaster smoothly mixed plaster


Once your mixture is smooth, slowly pour it over your mirror blank in your mold. You will want to fill the mold all the way to the top. Try not to overflow from the start however. After filling your mold, use your stirring stick to gently stir the plaster in your mold to get rid of any big bubbles. A little bit of your plaster may pour over but that is okay. After stirring take a ruler and gently run it across the top your your dam walls to get a nice smooth and flat surface on top. The plaster will generally set in 30 minutes but you should let it sit overnight to fully harden, especially for larger disks. DO NOT POUR ANY LEFT OVER PLASTER DOWN A DRAIN.

Pouring the PlasterStirring the PlasterLeveling the Surface
pouring plaster into mold stirring plaster leveling surface



Step 4. Curing and Sand EdgeSanding Edges

After your have taken your plaster disk out of its mold you will want to set it on a baking rack to cure for a few days. This allows the bottom side to harden fully as well. After the disk is fully cured you will need to take a piece of fine sandpaper and smooth over and bevel the top and bottom edges. You can also sand down any bumps that may have formed on the top surface. Make sure to thoroughly wipe off any dust you sanded off before water sealing your disk

Step 5. Arrange tile layout
The next step will be to plan the layout of where you will be gluing the tiles on your disk. Start out by finding the center of your disk. You will want to put the point, not the center, of your first tile at this spot. From here you will spread the tiles out next to each other while leaving a small gap between each. This will create channels that allow your grit and water to flow freely. Do not allow any tiles to hang over the side of your disk. While some take the effort to cut tiles to fill up as much space as possible it is okay to use only whole tiles and leave some empty space near the edges. As you lay out your tiles make some markings to use as a guide later. This will make glueing the tiles on much easier.

Placing First TileArrange Tile LayoutMarking Tile Layout
placing first tile arrange tile layout marking tile layout


Step 6. Water sealing your diskWater Sealed Plaster Disk

Now that you have your tile layout marked out you can seal your disk with epoxy. Mix the Epoxy according to the instructions on the package. Keep in mind that the epoxy will set pretty quickly so you will want to work fast. Coat your disk on the top surface and side to start. Use your foam brush to try to get a nice and even spread. Once the epoxy has fully cured you can flit the disk over and coat the back side. Once both sides have cured check over the disk and if needed add a second layer of epoxy. You do not want any water to be able to get through.

Step 7. Glue tiles to your disk
With your disk completely water sealed you are finally ready to glue on those tiles. If possible ask for some help from a friend. It is nice to have a second pair of hands mixing more epoxy as you need it. This way you do not feel as rushed when placing tiles as your epoxy is curing. You will want to spread the epoxy on your disk thick enough that it will come up on the side of the tile a little bit. This helps to seal the edges were the tile and disk meet and keeps grit from hiding here. While placing tiles make sure to give them a little wiggling in so that they are seated nice and flat on the disk. Once you have each tile placed, allow the epoxy to cure overnight and then you will be ready to begin work on your mirror!