Sealing will NOT prevent etching. Plenty of personal care products will etch marble. It happens.

I know and am ok if it's my fault, but I'm beyond certain that nothing has spilled on this surface except water and maybe a little soap. I won't even use nail polish/remover or hair color in this room. No toothpaste or mouthwash has spilled. Can water damage the surface?

Yes, some water can damage marble. Depends on the pH and mineral content. Soap can damage it too.

Yep, hard water can do it. Also it's possible any overspray from other cleaning or personal care products.

We don't have hard water. I know what those hard-water spots look like, though. This is more of a dullness. Seriously, these counters are only a month or so old, and nothing chemical has been used anywhere near them. The polished marble floor has no such problem. Is there a way to test whether the sealer was applied?

The material has barely been used. I assume sealer shouldn't wash away after only a month. I'm almost afraid to ask, but if it wasn't sealed, what can get rid of these spots before sealing? Would it have to be re-honed?

Sophie,

Thanks for the photo. Mine doesn't look like that, though. It's more evenly distributed areas of dullness, about 1/2" in general.

Sealer DOES NOT have a thing to do with preventing etching. Etching is a chemical reaction between a base (your marble) and an acid (water, cleaning products, etc.). It's a small area where the marble dissolves, which changes the surface sheen and texture. The ONLY way to prevent etching is to coat your marble in plastic. Then, it looks like plastic.

If you have your doubts as to whether or not it's an etch, post pictures. Distance and closeup. But, given your description, it's normal.

helsharmar:

I think you were kidding yourself. You are not prepared to live with etching.

I've tried taking photos, but since the marble isn't a uniform color, I can't get anything that shows what I'm talking about. I got a "test" piece before choosing this. I dripped all kinds of bath products on it, and it didn't have these marks. I think I understand the difference between staining and etching, and it was explained to me that sealer doesn't prevent etching and isn't really a barrier. It somehow forces the stain up and out. Unfortunately, my contractor switched subs at the last minute and didn't use the place that gave me the sample, so I don't know what they did or didn't do, except that they tried to use a cracked piece of marble in one spot. I tried speaking to them directly, but they have been evasive.

Should have got porcelain that looks like marble instead of real marble in my opinion. Cheaper, more durable, and impermeable.

I considered the alternatives, e.g., quartz, quartzite. Decided I'd trade the look of real marble for the durability and easier care of the others. Not expecting perfection, just want to make sure appropriate measures are taken.

Porcelain absorbs water at 0.5.

Pictures are needed. Shine a light at an angle to increase the light being reflected off of the surface.

Do you know what material you actually have? Is it possible they switched it on you?

kats, Why would you ask that?

I was just curious. it sounds like you tested samples and put them through pretty rigorous testing. GC switched subs and potentially supplier. Now you have a permanent install that you are treating really carefully and it is etching or staining. Seems like something possibly changed in the work stream, you know?

I agree pictures would be really helpful so those experienced with natural stone can weigh in. Even if your pictures aren't perfect, someone can probably tell you if that is normal or an issue. It could be staining, etching, mastic residue, etc...

I'm pretty sure it's marble. My doubt concerns the sealer. I will try different lighting to see if a photo will show the spots. Maybe I can remove them with a certain product, but I was told not to use anything but soap and water.

I have/had marble countertops in my bathrooms and I can't wait to have them all gone. They do not hold up well. Our counters are about 15 years old and they look awful.. Stain easily and I question their durability in a place such as a bathroom where all of kinds of items are used and sprayed. It sounds as if you can barely do anything in your bathroom because of the countertops.

Applying a sealer doesn't affect the surface texture, or the etching of marble. If you have issues with a sealer, you would be seeing water soaking in, or stains, etc. Changes in surface texture are almost always etching, or hard water deposits.

That's helpful. Water isn't soaking in. We have a water softener, so likely not hard water.