I have granite counter tops in my kitchen and wonder if I haven't messed one of them up.

I had a bottle of dish detergent sitting behind the sink, and it trapped water beneath it for several days. When I moved it, the granite was dark and discolored where the bottle had been. Over the next week or so the darkness faded considerably, and today looks like the photograph below.

If I leave it alone, will the discoloration gradually fade away completely? Is it caused by moisture actually impregnating the surface of the granite? If it doesn't go away is there any remedy? And is there anything I should have done (other than not leave a wet bottle sitting there) to prevent this?

tanstaafl.

Generally speaking, yes, the water will eventually evaporate and the granite will get lighter. Now, if you had food stains (wine, berries, etc.), it's another matter entirely. (Random Internet advice that worked for me: making a slurry of flour and hydrogen peroxide, smearing it on, covering with plastic wrap, and leaving for a few days. Your mileage may vary, try in an out-of-the-way spot first, etc.)

I've tried a variety of granite sealants, and none have particularly prevented the very issue that you're seeing for yourself. If you can find better, I'd be quite curious.

If it's just water, heat will pull it out, otherwise It might set the stain.
I don't think I would try heat.

I recall seeing a video on tv about using poultices on granite.
googling for granite cleaning poultice turns up relevant links.

At the risk of stating the obvious, water isn't dark. Micro-organisms growing in water are dark. Any remaining darkness is probably the remnants or spores of shrivelled, dried-up, died-of-thirst micro-organisms. What you need is some sort of bleach strong enough to bleach organic material but not strong enough to corrode granite. Whether or not hydrogen peroxide falls into that happy medium I couldn't myself tell you, but if the Internet says so it must be true...

Peter

From everything I've ever heard, Dan's suggestion is what you're supposed to do. I believe it works for marble as well.

In fact, they talked about this on the last season of This Old House. They were installing marble countertops which stain even easier than granite (particularly the kind of marble they were installing). The demonstration was more aimed at getting rid of a wind stain, but I'm pretty sure they said it applied to anything. They applied the slurry, covered it in plastic wrap, taped the wrap to the counter (with blue painter's tape, I believe), and left it for like 2-4 days.

*edit*
It isn't from the episode I was talking about, but the This Old House website has instructions.

Nice!

Thank you.

tanstaafl.

No problem! It doesn't mention water specifically, but I would imagine that it still applies...

I think I may respectfully (very respectfully!) disagree. Water may not be dark, but I think that granite saturated with water may well be.

The stain in the photograph is MUCH lighter than it started out to be. I had another stain caused by leaving a wet pot lid on the counter top. The stain was a thin ring where the lid sat on the granite. Over a period of weeks this stain disappeared entirely, leaving not the faintest trace as the water dried out.

So, I have hopes for my dish detergent bottle stain, it seems to be getting better on its own, but the flour and hydrogen peroxide trick is there as a backup.

tanstaafl.

Friends of ours have the same issues (as Doug), down to the fact that it was water/soap accumulating under their dish-soap bottle. They've since started putting the soap bottle on top of a small plate, but they're still left with the original stain. I'll definitely forward them the link.

I think the only time I'd put granite on a counter top would be if it were included with the house and I had the option of black and honed texture. If I were to ever replace our laminate counter I'd probably go with soap stone (non-porous, doesn't need to be sealed).

I'm not sure of the purpose behind stone countertops. They certainly can be attractive, but they seem to be hard to care for, and it's a bad idea to cut directly on them (it'll wreck your knives), not to mention that stone mining is not exactly the most environmentally friendly process in the world.

It's really not usually a big deal. My parents had granite countertops in our family home for 15 years or so, and there was never a stain anywhere on them. As long as you wipe up water in a reasonable amount of time, and don't leave things like dish soap bottles on the counter, you're completely fine.

IMO, the purpose of a solid surface (not just stone) counter top should be for relative longevity, attractiveness, ease of use and care.

I've had a lot of laminate counter tops. You don't have to wipe water off them since the laminate is completely water proof - EXCEPT at the seams. But you can't put a hot pot down on it.

That's where granite also falls down as well. It will stain - easier than marble if untreated, and you can't put a hot pot down on a sealed granite counter. What's left is simply the aesthetic, IMO. Which is still a valid reason for having something like this installed. Though if you're into baking, the cold stone is also very nice for working on dough - though marble is likely even better than granite here.

I only cut on wood and very occasionally on a polymer cutting board, so it doesn't mater what a counter top is made of WRT to cutting (for me). In a larger kitchen I've love, soap stone which I've already mentioned, and at least one large section of counter top made of hard maple (butcher block). Then I really could cut on the counter.

"They certainly can be attractive..."

That about sums it up, Bitt.

tanstaafl.

I don't think there is any counter top you would want to use a knife on directly.

Personally, even if I could, I wouldn't want to work on any countertop directly anyway. It seems to me that it's far more sanitary to use cutting boards, and easier to clean up as well. Besides, knives prefer wood for cutting. Much faster. I use plastic boards for meat and fish, though...

And I'll reiterate my previous statement that granite countertops are not hard to care for and maintain. Like I said, 15 years with zero wear on the stone.

If you don't mind scarring, then you can cut directly on pretty much anything a counter is likely to be made of but stone and glass.

My point, though, was that some people might think that because the stone is unlikely to get scarred from a knife that it might make sense to cut directly on it.

That granite surface is a delicate, mirror finish that would scratch quite easily if a knife were applied to it. In some ways granite is more fragile than conventional counter top materials like Formica which have a little bit of give or flexibility that allow them to resist trauma. Granite is hard, but steel is harder.

tanstaafl.

Granite is mostly quartz. Quartz has a Mohs hardness of 7. The majority of the rest of granite is feldspar, which has a Mohs hardness of 6, so it's softer. Quartz's Knoop hardness is about 820.

Most quality kitchen knives are made of 440C stainless, which is a very hard steel. It has a Rockwell hardness of about C57 when hardened and tempered, which is more-or-less equivalent to a Knoop hardness of 670.

I don't know what's used to polish granite, nor do I know if the other minerals in yours particularly are soft. But granite is, by far, harder than steel.

You can easily chip a knife on a granite counter top. You can also scratch granite with a knife. You will definitely dull the knife edge and possibly ruin the knife eventually. It's also dangerous because the knife may slip as you're cutting.

In terms of dollar per surface area, my knives are worth a lot more than any granite.

When I see people cutting on a glass "cutting board" it's almost as bad as hearing someone run their nails on a chalkboard. I'm sure cutting on a granite counter would get me the same way.

Bah! My mind is made up, don't confuse me with facts!

It will no doubt damage the knife in the process, but a knife WILL scratch a granite counter top. Since the most expensive knife I own probably cost about $12, and my granite probably cost about a hundred times that, I will be keeping my knives away from my nice, shiny counters.

tanstaafl.

Guys, I still haven't heard your response to my question:

Why are you cutting on your countertops?

I have never in my life cut directly on any countertop. I'll repeat my statement from an earlier post in saying that cutting boards are far easier to clean, using plastic for raw meat and fish is more sanitary, and it's all moot because wood is a better surface to cut on anyway.

So yeah, I really don't understand what you guys are arguing about. IMO, the material for the countertop is purely about the aesthetics. As far as care goes, I still maintain that you can't do any lasting damage to granite as long as moisture is wiped up in a reasonable amount of time (like...an hour or something).

I never even considered cutting directly on the countertop as an option. I think I have like five cutting boards (two nice wood ones and then some cheap plastic ones) and it never occured to me to not use one of them.

I was merely offering that as a possibility for a reason for why someone might want a stone countertop, not claiming that anyone should do it.

When in doubt, I lay my Bosca wallet on my granite counter top and cut on *that*.

Cutting on wood is nasty. Think of all the food substances it might absorb - runoff from uncooked meat is the deal breaker for me. I cut on a granite cutting board on top of a granite counter top.

My granite counter tops seem easy enough to care for. Just don't get them wet, like Gremlins. And don't get oil on them. So my soaps and sponges are all in little dishes, and my cooking oils live on a decorative tile on the stove top.

No more water-soaking pressboard covered with laminate for me.

Dude, you're definitely not supposed to cut meat and fish on a wooden cutting board. That's what plastic is for. Wood is for veggies and fruits and stuff.

Am I the only Good Eats fan here?

I will cut chicken on a plastic cutting board but only because I'm usually using the wooden one at the same time for something else. People have been cutting meat and fish on wood for thousands of years and I don't see a reason to change that any time soon. Just follow safe food handling practices and clean up. BTW, you can sand down a wooden cutting board to make it like new again.

Alton Brown can go get stuffed. That guy bugs me.

Cutting on a a stone surface is nuts. I don't want to have to replace my knives every year and I don't want them dull in between.

Well that much we agree with. Besides, didn't we all just get done saying that stone is basically porous and therefore is probably taking in just as much bad stuff as wood would, if you're worried about that?

Ummmm... that turns out not to be the case.

Due to the natural antibacterial qualities of wood, it is the preferred material for cutting boards. Research here.

Excerpt: Although the bacteria that have disappeared from the wood surfaces are found alive inside the wood for some time after application, they evidently do not multiply, and they gradually die. They can be detected only by splitting or gouging the wood or by forcing water completely through from one surface to the other. If a sharp knife is used to cut into the work surfaces after used plastic or wood has been contaminated with bacteria and cleaned manually, more bacteria are recovered from a used plastic surface than from a used wood surface.


They tested different types of wood with really nasty bacteria (salmonella and e-coli) and the wooden cutting boards were safer.

tanstaafl.

And my stone cutting board, with its many knife scars torn into the surface, must be more porous than most. You know, it sure was easy to wash a small wood cutting board under scalding hot water after cutting chicken on it. The stone cutting board? That's not moving any time soon.