How do you break slate to use in a mosaic? It keeps shattering!?

Question

I am making a random pattern mosaic on my front prorch (concrete surface). I have boxes of 12 x 12 tiles and I'm trying to break them so they won't be a uniform shape and won't have any straight edges.
Problem is...EVERYTHING I've used to cut or break these tiles causes it to shatter! It's softer than most tiles and is made up of layers, so I can't get a clean break. I can get maybe 1 good piece for my mosaic out of a 12 x 12 tile and I'd get 3-4 pieces from a different type of material/tile.
Here is what I've tried so far: tile nippers, score and crack device, hammering it, cracking it over the edge of a concrete stair, dropping it...
Anyone ever have success breaking or shaping this stuff? I have a tile saw, but that would give me a straight line/cut and I want uneven edges that look natural.
Thanks!

I have 70 sq feet of this tile and have used about 1/4 of that so far. The porch I'l mosaicing is 60 sq. ft.
The tiles do not have a finished side. Either side can be placed face up.
I wouldn't have chosen this material if I'd known in advance how difficult it is to shape, but I'm on a mission now! There was a lot wasted since the tiles partially shattered, but I do have about 20 sq ft of good pieces that I can use. I still have 3/4 of the tile left to work with, but it looks like I'll have to buy more at the rate this stuff crumbles.

Answer 1

How about wrapping it in a bath towel, and using a rubber mallet to break it?

Answer 2

Folks have breaking slate for centuries for roofing tiles. SOMEBODY knows how to do it. Here are a couple of ways I know that will work: Diamond saw blades, either rotary or coping. I've worked with both to cut marble, granite and slate. They work fine.

You can rent a tile cutter with diamonds, they'll charge the rental ($30-40/day) plus some minor charge by the 10,000th of an inch (I think?) for the wear on the blade.

Good luck.

I just this minute scored a relatively straight line on an old slate shingle. I used a diamond Dremel bit. Laying the tile over a sharp edge (table edge, straight plank, whatever I find handy,) aligned with the score I hope that rapping with a hammer will work. If it does I'll come back in a few minutes to let you know.

Answer 3

Ive worked with slate hundreds of times andto do what you are asking it to do will take tons of slate tiles just to get what you want. Like another said, slate is in layers, and will break along its natural weaknesses first. If you notice slate tiles are almost twice as thick if not more than a ceramic and thicker than marble and porcelain tiles because of its compsition. You may want to consider another material suitable for outdoor use or buy a ton more of slate and hope for the best.

Answer 4

I applaud that you're already aware of the substance and composition of Slate... in it's being layered. I guess I'm curious about why you might not just try a "stone yard" for various sizes and shapes.

You already have "Boxes" of the material, though don't state how many, or how many pieces you have, or may have wasted.

I recently did my entire floor in Terra Cotta tile I broke up with a simple piece of 1 x 3 rosewood, just tapping at the tile, but it wasn't slate.

Does the "tile" have a factory finished bottom side? Have you attempted breaking from the underside? One thing you might try if you haven't. Find a rock,,,especially one that is stable enough to use as a kind of base/break point tool, perhaps with a rounded, cone type point on it. Hold a piece of tile face up and slam it, (gently maybe) "centered",,, down onto that point. The thought is, not having such a narrow impact point, as you do with a hammer. What you're trying to do is spread the impact, say in 4 directions, to achieve the largest pieces possible.

You may still end up with some shards, and the process may make as much waste as viable pieces, which only you can know, in knowing how much material you have to work with, determining a size for the finished project, perhaps compromising that a bit?

Steven Wolf