Introduction: How to Polish a Damaged Marble Countertop

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When we bought our condo, the marble countertops in the bathrooms were already badly damaged by inappropriate cleansers. In one bathroom, there were drip marks and the imprint of a spritzer-bottle from something acidic (acid dissolves marble), and in the other, the area near the sink was completely dulled by the use of an abrasive powder.

Marble is a rock, but it's also quite delicate. Some of you may be reading this because you just learned that fact the hard way, and if so, my sympathies! This Instructable will explain how to repair some of the damage.

But first, a public service announcement: NEVER USE TOOTHPASTE OR ANTI-PERSPIRANT TO POLISH YOUR COUNTERTOP, omigosh. You may have read about people trying that, but it is a baaaaaad idea, and when you read farther into their tales, you invariably see them say, "Yeah, it made my counter look even worse."

The reason why is that when you polish something, you want all the abrasive particles in your polishing slurry to be the same size. If they're not the same size, then the big particles will constantly scratch up the polishing that the smaller particles are trying to do, and you never get a shinier surface. The big particles will just keep gouging it up.

The abrasives in toothpaste and anti-perspirant are not sorted by size, so you will never get a good polish on your countertop with them, and you will probably make your counter look worse than it currently does.

For that reason, there is only one "hard" thing you need to do in this Instructable. You have to buy the right polishing compound. You cannot cheap out with a Home Depot maybe-it's-equivalent product, and you can't swap in some household goo; you have to get the right stuff.

What you want to buy is Aluminum Oxide "polish" powder with a grit-size of somewhere between 1 to 3 microns. There are other things that will work, but this is a common product and a really dependable one.

Where do you buy this stuff? You can get it from a store that sells supplies for "lapidary" enthusiasts (lapidary means stone-polishing), rock tumbling hobbyists (which is also stone-polishing), and sometimes for jewellry makers. You can also order it online.

They sometimes don't know the exact grit-size of what they're selling, but if it's called "polish" and is used in the final stage of rock-tumbling, then it will work fine for you.

You're not going to need more than a little sprinkle of it, so buy the smallest container you can.

What else will you need? Well, here's the complete list of supplies, including the polishing compound:

LIST OF SUPPLIES:

  • Aluminum oxide polishing compound with a grit-size somewhere between 1 to 3 microns
  • Disposable fabric rags (squares of clean denim are ideal for this)
  • A spritzer bottle of water
  • A rectangular object you can use as a sanding block

Fun fact: Aluminum oxide is sapphire. Very tiny sapphires, but that's what it is. It's also what's in your anti-perspirant, which means the reason you don't sweat is because you've clogged your armpits with sapphires!

Step 1: Safety Concerns

Safety concerns?! Wait, is this counter-polishing stuff dangerous?!!

Well, no, not at all, but there's something you should be aware of. Small particles of silicon in the lungs can cause a deadly and non-treatable condition called silicosis, although it generally it takes many years of exposure before your health starts to be impacted. Small particles of other stuff, like coal dust, can also be deadly in a very similar way.

But that said, the amount of exposure you could get from polishing your countertop one time is utterly negligible, and marble doesn't even have much silicon in it (granite does, however). Regardless, there's a really simple way to protect yourself from even this negligible danger: Just keep everything wet.

When the polishing compound is kept wet, it sticks to your counter, or to your rags, and it's not floating up into the air as dust. That keeps it out of everyone's lungs. So even though there's almost no danger involved in this, please do the following to protect you and your family's health:

  • Only wet-polish your countertop, i.e. keep the rag with the polishing compound on it wetted down with water while you work.
  • While you work, also keep the surfaces you've already polished damp by spritzing them down with a water bottle.
  • Once you're finished, clean up the area with wet rags, making multiple passes over the surfaces you've contaminated, with multiple clean cloths, in order to get all the polishing compound wiped up.
  • Then, when everything is clean, you're going to pack up all your rags--while they are still wet--and take them outside your house and put them in the trash.
  • And, finally, wash your hands.

That second-to-last step, taking out the trash while it's still wet, is so that the rags don't dry out in your house, where they might get bumped and release puffs of dust into the air. Because the particles involved are so small, that dust can stay aloft in the air for a surprisingly long time, making it more likely to wind up in someone's lungs.

But again, the actual danger here is incredibly small, so try not to panic about it. Just do your best to keep things wet while you're working, and then to get everything cleaned up and the trash taken outside while it's still damp after you're done.

Step 2: Facts About the Polish

Here's the good news: If you bought the right polishing compound, then there is very little here that you can screw up. It's incredibly easy to polish your countertop.

The somewhere-between-1-and-3-micron polishing compound I've recommended is fine enough that, if there are still some shiny areas on your countertop, the polishing grit won't damage that shine at all. It will only attack the rough, non-shiny areas. That means you can only improve the appearance of your countertop, not mess it up.

The lone bit of bad news is that because the polishing grit is so fine, it isn't very aggressive. That means you can't erase really deep damage; you can only improve on its appearance.

Here's what my freshly-washed countertop looked like before I started. It's completely dull, with no shine at all, and in fact, I could feel the surface roughness caused by the use of abrasive powdered cleanser on the marble.

Step 3: Getting Ready to Polish

I assembled my supplies, which consist of my polishing rag (and my clean-up rags for later use, not pictured), a spritzer bottle of water, my polishing block, and my polishing compound in the little plastic tub, plus a spoon (not pictured) for sprinkling the compound onto my polishing rag.

Next, I sprinkled a bit of polishing compound on a damp cloth, then spritzed it with water so the compound itself was also wet. You really don't need very much of the compound.

Step 4: Polishing!

I flipped the cloth over onto the surface and wrapped it around the polishing block. Then I started polishing!

Step 5: Cleaning Up Afterward

Finally, when I was done, I cleaned up the area with multiple passes of wet, clean cloths. Then, I threw out the cloths, and bagged that garbage up and took it out of my home while it was still wet. This prevents the dust from getting into my home's air once the rags dry out.

Step 6: The Final Result

Here's my before and after shots, after just 10 minutes of fairly slap-dash polishing.

Note that the counter is NOT glossy, but that's because it was a badly damaged surface when I started. After the polish, you can see it's got a subtle shine.

I should be able to improve on this level of shine simply by polishing for longer, but even 10 minutes gave me a significant improvement. And as I said, there's almost no way to screw this up: You just rub the countertop all over.

Getting a perfect, super-glossy polish with 3-micron grit probably isn't possible, but you should be able to get a really good shine, and you can buy smaller grit and do a second pass if you really want to try for that mirror-bright gloss.

I hope this Instructable helps you restore the beauty of your home's countertops. Thanks for reading!