Dark Stain On Marble Countertop

QUESTION:

My kitchen countertops are honed "Michael Angelo" marble (white with gray and taupe markings).


About a year ago a dark stain appeared by the sink. I don't know what caused the brown marble stain.

It happened pretty suddenly. I'm thinking something my cleaning lady or a friend spilled.

It has darkened a bit with time and even seems that it may be spreading. Looking at the edge around the sink it appears as if it goes all the way through the marble (3/4" thick).

I have read on your site and others about using bleach or peroxide, which I was going to try, but thought I would contact you first for any other insights.

ANSWER:

Good thinking to get some concrete advice about cleaning marble first.

Experimenting is risky when attempting to remove a stain in marble. Often people just start trying different products or methods. This is a gamble as many cleaning products could cause further damage to the marble countertop.

Most homeowners simply don't understand how marble stains occur and know even less on about how to remove natural stone stains.

The cause of the stain is what we need to figure out first.

This stain is brownish and spreading. Your average stain in natural stone does not do that, so looks like this is a special case.

Four things to consider...

1. Marble stains don't really spread unless something continues to feed the stain. Once a liquid absorbs and then dries... that's it... the stain is static and does not grow.

2. The stain has a dark edge around it. Most stains will be darkest in the middle and fade out toward the edges. The dark edge suggests that it is spreading in that direction.

3. White marble often contains iron deposits which can cause yellow-brown rust stains when exposed to water. This happens a lot in white marble tile showers.

4. The stain runs over the edge of the countertop surrounding the sink which could mean that it is full-thickness or that the staining substance spilled over the edge.

However, stains rarely occur from a liquid spilled on a vertical surface since the liquid will usually run off before it has time to stain.

So, it's more likely a full-thickness stain which would only occur with a constant source feeding the stain like water from the sink.

My best guess then is that this is a rust-type stain developing from water from the sink getting trapped under the marble countertop.

This could occur if the caulking around the sink has gaps which could happen over time which would explain a rather sudden development of the stain.

I recommend you check caulking around the sink and repair if needed. Also check the underside of the countertops (viewing from inside the cabinets) around the sink to see if anything needs fixing underneath.

If the marble countertop was installed onto plywood sheeting over the cabinets, then water could easily get trapped between the plywood underlayment and the marble countertops.

Then work on removing the stain. Full-thickness stains and rust-stains are very difficult to remove, but you should have some success removing the stain from the surface or at least lightening it.

To remove the marble stain follow the steps outlined in the Removing Stains Manual for granite and marble maintenance.

The procedure varies depending on what actually caused the stain. It's probably a rust stain, but the manual contains instructions for every type of stain so you can try different methods if needed.

To make things really simple you can use the Rust Stain Removal Poultice. It's pre-formulated with instructions and easy to apply.

One additional possibility is a glue stain from the adhesive used during installation.

A full-thickness stain typically indicates something absorbing from underneath and sometimes this is the glue used during the countertop installation.

Installation adhesive stains may not show up right away, they can darken, spread, and are extremely difficult to remove.

The stain in the photo does not appear to be glue stain, since usually glue stains are more gray - green, but it could be if it appeared within days after the marble kitchen countertop was first installed.

How to Clean Marble and Avoid Damage

Common generic cleaners like bleach, vinegar, hydrogen peroxide, and ammonia are popular and effective for many cleaning projects around the house. Just keep these away from marble. All will etch (corrode) marble and dull the surface.

Really, most brand-name cleaners are too harsh for marble as well.

In general, using marble-specific cleaners only is the smart bet.

Sometimes hydrogen peroxide is used to remove certain types of marble stains with a special process, but this is done knowing there is no other way and you will have to deal with any etching later.

Now you have honed marble, so any etching will not be as noticeable, but it still could be.

Marble stains are caused when a substance gets into the pores of the stone. You can't remove them by surface cleaning.

Neither bleach nor hydrogen peroxide nor any other cleaning product will get the stain out just by scrubbing.

This is where experimenting goes wrong for most people trying to remove a stain in a panic. Since regular surface cleaning won't work, they end up trying one cleaner after another and end up compounding the problem by causing additional damage like etching.

You may see some improvement with standard cleaning if done very shortly after the stain has occurred, however, it almost certainly won't completely remove the stain... and/or it may leave an undesirable etch mark.

Sealing marble will help prevent stains. And particularly for white marble like Carrara marble kitchen countertops and shower tile, sealing will guard against rust stains that develop from continuous exposure to water.

Conclusion

An orange, yellow, or brown stain in white marble near a source of water like your kitchen sink is probably a rust stain.

Repair any gaps in caulking around the sink, look for any plumbing leaks or anything else that could lead to water getting trapped underneath the marble countertop.

Then use a rust stain removal poultice to get the stain out.

Once the stain is remove, apply a stone sealer to prevent future stains.