How can I make the surface of marble rough without using chemicals?

Question

How can I make the polished side of marble not slippery? I don't want to use chemicals to do this because these pieces of marble will be used as stepping stones in gardens.

WHAT I'VE ALREADY TRIED: I used an orbital sander with 60 grit sandpaper on one today, but it didn't help too much. However, the paper has already been used so I'll get more tomorrow for the belt sander and start with 40 if the hardware store has it in stock. I'm not sure if this will work, so I'd like to know if any of you know if this is a waste of time. I'd prefer this method or an alternative if it is just as easy because the marble is gorgeous, and I'd love to keep at least some of the color and patterns.

If my first idea is a waste of time, then here's my next thought. If you flip the pieces over, the back of them would be perfectly fine to use, but there's two issues. 1. You cannot really see how beautiful they are, and 2. Some of them have netting on the back that is held in place by crazy strong adhesive, which doesn't sand away easily.

I don't know what to do for issue number two unless you have a suggestion. In regard to the first one, I thought maybe using the reverse process of what I want to do to the polished side on the back side. I want to use sandpaper to begin the polishing process to bring out some of the stones' colorings but stop before the surface becomes slick. This involves starting with a low grit sandpaper and working up to a fine grit. This would be a good idea, but it will take more time - a lot more time considering how much needs to be done.

Do you know if these ideas will work, and if you don't think so, then do you have suggestions that don't involve chemicals or applying gripping tape to the marble (which would hide the pretty)?

Answer 1

The polishing is what makes the beauty in the stone. Sanding/grinding it away will reduce that beauty.

If you watch any videos on stone finishing, you'll see that one of the techniques they use is flame surfacing. Using a large blowtorch, they'll heat the stone until the moisture trapped inside starts to boil. When it does, steam pressure will spall it, causing small (or sometimes largish) flakes to pop off. This will create a rough surface that is good for walking on, but will probably take some practice to get good at. Whether this will leave the "beauty" you're looking for or not is all within the eye of the beholder, so nobody but you can answer that. Perhaps go to a stone store and look at some flame surfaced stone of the same type(s) as what you've already got to see it that would be acceptable to you.

Your best bet might be to return the marble you've got and get some that's already flame surfaced by a stone company. Perhaps you could talk to them and have them do the surfacing for you on the stone you already own. Or, just set aside a few pieces as practice pieces and have at yourself.

Answer 2

Rather than jump right to 40, you might try a finer grit (since you want to "see the beauty" when you are done) of a stronger abrasive (than the used/worn probably garnet or aluminum oxide you tried.)

Be very wary of super-coarse grits.

Try AlZn (Alumina Zirconia) or Silicon Carbide in perhaps 100 or 80 grit before you head down the very coarse grit road.