A ceramic floor tile is a popular work surface for electronics (and other types of work). It protects your bench from the heat of soldering (and maybe the occasional battery explosion), and provides a hard, flat surface to do your work on. Using just a bare tile isn't great, though, because the rough underside can scratch your bench. In this instructable, we will coat the underside with spray-on rubber automotive underseal/undercoat material to give the tiles a softer and smoother underside. However, that might still be a bit slippery, so some rubber or cork feet can be added if necessary.

Step 1: Get Tiles

You want tiles that are as hard, flat, and smooth as possible. Ceramic tiles are good for this, and some hardware stores are willing to sell you one or two rather than a whole box of them.

I happened to find mine at a garage sale. They had many other tiles there, but most of them had rough textures, which I didn't think would be good for a work surface. The two types of tiles I got are smaller white ceramic tiles and larger stone tiles. The ceramic tiles are smooth, but they are not completely flat: there is a kind of ripple shape in the surface. The stone tiles are just about completely flat and smooth; there are only a few small voids from imperfections in the stone. The stone tiles are also not as hard; they take scratches from sharp metal objects. (This page says that means the stone is marble, not granite.)

Step 2: Get Other Stuff

In addition to tiles, you will need:

Underseal/undercoat spray. This stuff is designed to be sprayed on the underside of cars to protect against pebble impacts. The stuff I used comes in an aerosol can and isn't very expensive.
Rubber or cork adhesive feet/bumpers. Rubber will keep the tile from sliding around, while cork will let it slide a bit while keeping the underseal off of the table (because it could drag dirt around and scratch the table).

(Why not just use rubber feet and no underseal? The underseal provides a nicer surface for your hands when you pick up the tile, and it lets the feet stick on better. It also protects other objects from being scratched by the edges of the tile. However, if those don't turn out to be problems for you, you can choose to skip the underseal.)

Step 3: Clean the Tiles

If there is any dirt or grit on the tiles, wash them with soap and water. Rinse well, and then dry with a towel. (A paper towel will show if there's any soap left by re-lathering it against the rough surface, in which case you need to rinse the tile better.) Having the tiles clean will help the coating adhere properly.

Step 4: Mask the Tiles

Some tiles, like my white ceramic tiles, have edges that curve down from the flat front surface of the tile. Even my marble tiles look like they have square edges, but they're actually beveled a tiny bit. These will not make good contact with the paper the tile is resting on as you spray it, so some spray will get under and onto the front of the tile. Use painter's tape to cover the edges to prevent this. Even if your tile has square edges, it might help to mask them, because they might not sit perfectly against the paper (i.e. if the paper or the surface below it isn't perfectly flat). If your tiles have rough edges for grout (probably most tiles) then you'll probably want to cover those with the coating, so leave them unmasked. If you have tiles that have smooth edges, you can mask them and leave them uncoated. Up to you.

Step 5: Spray the Tiles

Lay down some paper to catch overspray and put the tiles on it upside-down. Spray them as evenly as possible, according to the instructions on the can. Make sure you get all four edges covered if you left them unmasked.

Step 6: Wait a While, and Then Pick the Tiles Up

The underseal spray I used dries pretty quickly. In five minutes to an hour, depending on temperature and coating thickness, it's dry enough to handle carefully. Yours might take longer—check the instructions on the can. Peel the tiles off the paper and then set them down, probably on some clean paper, because the coating may still be wet where it was in contact with the paper.

For my first batch (one of each type of tile) I waited about half an hour and the coating was dry enough to touch, but when I rested the tiles on the narrow edge of another cart, it left a deep imprint in the coating. Oh well. It'll still work. I also rested the smaller tile on top of the front surface of the larger one, and it stuck down, and I had to scrape little bits of coating off of the larger tile. It came off cleanly.

Step 7: Clean Excess Coating

Carefully peel off the masking tape, if you used it.

Take a knife or scraper and scrape off any excess coating around the edges of the tile. This is easier to do before it dries fully. You can even scrape it with your fingernail.

Step 8: Let It Dry Some More

Wait a day or so for the coating to fully dry, if necessary. I put them on the electronics workbenches at Protospace, because that's where they're going to be used, and they might as well be useful while they're drying. The flat surface won't exert localized pressures on the coating, like the edge of that cart did, so it won't cause any damage. The coating is dry enough by this point that it won't stick to the benchtop.

Step 9: (Optional) Add Some Feet

If you find that the coated tile slides around too much on your bench, you can add some rubber feet.

Take your rubber or cork bumpers and apply them to the underside of the tile, at the corners. Press them down hard so they stick well. For larger tiles, you might also put one in the center, to provide some more support in case heavy things get put on it.

You could probably also use small pieces of rubber sheet held on using more underseal as glue, though I haven't tried that.

Step 10: Laser Engrave

These tiles will be put in a shared workspace where most people using them don't even know me, so I thought it would be a good idea to label them as to what they are and how to avoid breaking them. And what better way to do that than by laser?

The second picture is the design I created for that, though I don't have a picture of engraving it. I do have pictures of a test engraving of Protospace's logo, and of engraving a Go board for my parents.

Settings (speed & power) aren't very transferable from one machine to another, even of the same nominal power, and I'm not sure I got the best settings on our machine, so I will leave you to experiment there. Fortunately, I found that the marble tiles are very forgiving of repeated engraving at different speeds and power levels.

To align the engraving with the outline of the tile, if your laser cutter doesn't have alignment guides, include a square to represent the tile's outline in your drawing. Then, exact process depending on how your laser cutter's software works, separate the square from the engraving design, maintaining their alignment, and cut the square out of a sheet of paper or cardboard taped down to the machine's bed. Then you'll have a jig to align your tile perfectly.

Then wrap it up and give it to somebody! It's easy to wrap, but the recipient will be surprised by its weight.