How to make mosaics: is hardboard a suitable base for mosaics?

Hardboard is a good base for your mosaics, as long as you limit the size of the mosaic overall, limit the size of the tiles, and do not display the mosaic in a humid environment. Avoid hardboard for outdoor applications due to the potential for deterioration. Assuming your tiles are quarter size or less and your overall tile size is less than 24″x24″, I have found that a 1/8 inch thick hardboard provides a suitable base. If your tiles are small, it’s amazing how flexible the mosaic is, even with grout, which means it can take a few warps before the grout cracks or pieces of glass break off. If your tesserae are large, or if you incorporate large pieces of stained glass into your mosaic, your base thickness should be greater because the mosaic cannot withstand as much warping (ie, the thicker the wood, the more resistant to warping). For example, suppose your mosaic measures 24″x24″ and uses a single piece of yellow stained glass to represent the bright sun that lights up the world. Let’s assume the diameter of the sun is 10 inches, which makes up a good part of the mosaic. It’s easy to see how a small deformation can stress that single piece of glass causing failure (ie breaking, popping). It’s like ceramic tile on a concrete slab base. As the concrete cracks and moves, stress is applied to the ceramic tile, and if the stress is great enough, the tile breaks. Therefore, you should consider the size of the tiles when choosing the thickness of your mosaic base.

Over the years, when doing many wall tiles that are 24″x24″ or smaller, I have found that my favorite backing is 1/8 inch hardboard. It is the dark brown material that the board is made of but without the holes. It is slippery on one side and rough on the other. I use this material only for dry and interior wall tiles that will not be exposed to moisture. I use this material because it is: 1) Relatively thin, 2) Relatively light, and 3) Rough on one side so the glue will grab it well.

The 1/8-inch thickness allows the finished tile to fit into a standard pre-cast frame. My glass tiles are about 1/8 inch thick so the overall thickness of the finished mosaic is only 1/4 inch. This allows me to buy a ready-to-use framework for next to nothing. I plan my interior wall tiles to be 16″x24″, 18″x24″, or 24″x24″, which are common sizes for pre-made frames. If you were to use 3/4-inch MDF or plywood as your base, then you would need to use a custom framing with enough depth to cover the entire thickness of the tile (ie 3/4-inch wood base plus 1 / 8-inch tiles equates to almost a 1-inch thickness.) Custom frames cost up to five times more than standard pre-made frames. For example, if I take advantage of the biweekly 50% sale at my favorite hobby store, I can get a pre-made 18″x24″ frame in a lovely style and color that best suits the tile, have the tile installed in the frame, install the hanging wire and install the paper backing, all for less than $25. That’s how it is! Less than 25 dollars. A custom frame can cost up to $150.

Not only do you save on framing costs, but hardboard is inexpensive compared to 3/4-inch MDF and plywood. I buy a pre-cut section of hardboard instead of a full 4’x’8 sheet. The pre-cut section is 24″x48″. Knowing that the height of my interior wall tiles is typically 24″ (which is the width of the pre-cut section), this allows me to cut the hardboard and get a 16″, 18″ or 24″ width for the base. my mosaic. For example, suppose I want my tile to be 18″x24″. The pre-cut width of the hardboard I purchase is 24″. I measure and cut 18″, resulting in an 18″x24″ piece of hardboard. The piece fits perfectly into a standard 18″x24″ pre-made frame. I measure and cut the hardboard with a standard circular saw and a “rip fence” that I make by clamping a 3 foot level to the hardboard with two C-clamps. The rip fence allows me to push the saw along along the straight edge of the level to ensure a straight and accurate cut.

I prepare the hardboard base by painting it with two coats of white primer. The main reason to paint it white is to get a white background onto which the glass tiles will be glued (Note: I always glue the glass to the rough side of the hardboard). Although I usually use opaque glass, the white background helps to brighten it up. The dark brown color of the chipboard makes the glass pieces appear opaque and dark, even though glass is supposed to be opaque. The secondary benefit of painting your hardboard with a primer is that it seals it. I don’t know if sealing hardboard does anything, but it makes me feel better believing it’s sealed. I don’t know the material or chemical properties of hardboard and how it’s made, so I don’t know if it needs to be sealed, but painting it gives me a nice warm fuzzy feeling. I have a habit of sealing everything whether it is necessary or not.

After applying the tiles and grout, you’ll be amazed at how flexible the mosaic is without causing glass or grout failure (assuming your tiles are relatively small). When I first used 1/8-inch hardboard as a backing for a mosaic, I experimented and found that I could bend the mosaic two inches without affecting the glass and grout. I was too afraid to bend it more than two inches! After the experiment, I assumed that if the tile can bend five inches, then it can survive any deformation that might occur. Then after installing the tile on the precast frame, I realized that the tile was installed in such a way that it inhibited any warping. The mosaic was pressed down and held in place with small fasteners at the back of the frame to prevent it from falling off. The only way the tile can warp is if it is strong enough to cause the frame to warp with it. I have never had a problem with interior wall tiles warping when using 1/8 inch hardboard installed in a standard precast frame.

The 1/8-inch hardboard is also light enough that the weight of the overall tile isn’t so heavy that you have to remodel your home to create a support structure strong enough to support the weight of a tile. . Typically my 24″x24″ (or smaller) tiles are light enough to hang properly using a picture hook and nail installed into drywall. I don’t have to cut the drywall to install 2″x4″ pieces between the studs and then replace the drywall. This is extremely advantageous, especially when selling or giving away the mosaic (i.e. you won’t lose customers you might otherwise lose if you tell them they have to hang the mosaic by doing more than just driving a nail into the wall).