blackened terra cotta tiles

[linelle]

There are terra cotta tiles covering most of my small backyard. They were installed by the previous owner, and are at least 7 years old, probably closer to 12. I'm guessing they're unglazed and haven't been sealed, if ever, in more than 5 years.

Up until this year, they've gunked up a bit during the wet winter months and have cleaned up pretty well in the spring, with mild soap and scrubbing. But right now they look pretty bad, with some tiles covered in black. It seems to be more than surface mold/mildew. It looks like a stain. I'm sure not sealing them (maybe never!) has contributed to their sorry state. I can't think of tearing them up or replacing them at this juncture, but I do need to improve their appearance.

Any suggestions on how to clean them? Once they're cleaned up and the weather gets warm and dry (I'm in the SF Bay Area), is it safe to apply a much-overdue sealer?

Thanks in advance.

[Sponsored Links]

[doitright]

Hi Linelle, Welcome! :)

Can you post a picture?

Is this in a shaded area?

I have had great success using Prosoco's 2010 All Surface Cleaner to get the heavy buildup removed, followed by D/2 Antimicrobial for eliminating the deep mildew that may be present. You may need professional services to get desired results.

Get it clean (and dry), before you consider sealing them.

[kcstoneguy]

not knowing what is on the tile, I would try a few cleaning agents and see how they work, like a stripper or a degreaser. if its outside and black, i am kind of thinking mildew, in which case a little clorox and water might work..saltillo can also be sanded if need be..outside I would suggest a good penetrating sealer to protect against future problmes

john jackson
integrity stone

[linelle]

Thanks so much for the warm welcome and responses to my post. :)

Attached are two pictures. One shows how the blackness is distributed among the tiles, the other is a closeup of some intriguing marks, which are almost like india ink.

The backyard is small and is on the east side of the house, with a southern exposure. It gets a healthy dose of sun in the summer, but of course there is a lot of wet and shade in the winter months.

The tiles beyond the picnic table are a different kind than the ones in the foreground. I suspect they also predate the latter. Some of the stuff is clearly mold/mildew (I'm not really sure what's the difference or if it matters in this instance). Some tiles are completely covered with the black stuff, while adjacent tiles are clear. I wonder what that means.

Thanks for your help!

[Steven Hauser]

Hi Linelle,

I would follow the cleaning instructions but I will tell you not to seal them.

Some of the mold and mildew is indeed on the surface. This will never change unless you can get more sunlight shining directly on the tiles more frequently.

Some of it looks like it goes deeper.

Because of those two reasons I would just clean it, and be prepared to do it for as long as i owned the house.

:)

[doitright]

Hi Hilde :)

Thanks for the photo's (speak a thousand words). :)

Try tapping on those tiles that are extremely black. If hollow sounding, you may be holding excess moisture underneath them.

[kcstoneguy]

just mix a little bleach or clorox into some water, like 1:8 (water),,,then mop it out and scrub with a deck brush. it appears to me most of that is mildew. degreaser willnot probably work. you often get that appearance on concrete and limestone trim as well. I clean some limestone endcaps using a concentrated ph7 stone cleaner last year and a hand brush...just melted it awway...

a penetrating natural stone impregnating sealer would help as well, not a topical sealer

john j
integrity stone
kcmo
www.integritystone.com

[Arn]

Whiten them as best you can. bleach/water, tilex, whatever it takes to clean that mold. during the hot months of course.... when they are where you are happy with the look, I would look into a quality EXTERIOR saltillo sealer, and plan on sealing every year or so...

best of luck

[linelle]

Well, it finally got warm and dry here in the Bay Area, after a very wet winter. Suddenly it's in the 80's. What spring?

Today I scrubbed these tiles with warm water with some bleach and a deck brush. I still have a bit more to do, but I'm worn out now. Basically, the surface gunk came up, but the mold/mildew is real tenacious. If I get down with a toothbrush and some Ajax, I can get all of it up, including the black spots that look like India ink. But I have over 300 tiles, and I have no intention of doing that to each one! :sick:

While the initial scrubbing has made a vast improvement, I'd like to knock out more of the black. Someone earlier (sorry I don't have your name in front of me now) mentioned: success using Prosoco's 2010 All Surface Cleaner to get the heavy buildup removed, followed by D/2 Antimicrobial for eliminating the deep mildew that may be present. I think I've done my best with the bleach/water method, so anymore input on these products?

Thanks so much!

[doitright]

Hi Linelle :)

That was me with the Prosoco EK 2010 and D/2 Antimicrobial suggestions. What did you need to know?

Have you used a pressure washer yet? :shades:

[B. Yager]

The older tiles look like original Saltillo which I've found to be more porous than the newer tiles which could be why they are much blacker and allows the mold to grow as they stay wet longer. Does any water stand on the surface in low spots after rain in the areas where they are the blackest, what are they layed on, concrete pad or just set in mortar. Also what kind of ground is around your house sand, clay ect. all of this can contribute to your problems. You have planters that could be allowing water to go under the tile and keep it wet longer, if you don't fix the water problem you will have a never ending battle

[linelle]

John, thank you for finding me again. I'm interested in whether either Prosoco EK 2010 or D/2 Antimicrobial could knock out a bit more of the mold/mildew still blackening the tiles.

Brian, I wish I knew enough to answer your questions about what's under the tile. I have no idea. I realize that whatever I do is just a temp fix during the dry weather and it will come back during the winter. I just have to deal with what I have right now. I don't think too much water is coming out through the bottom of the planter. I'm fairly judicious with my watering, but who knows?

[doitright]

Hi Linelle :)

Can you post a current picture? :shades:

[linelle]

Sure thing...here they are. It's probably hard to see any improvement, but I got a lot of surface discoloration off. Even the blackest stuff will come off, but it would take me all summer and beyond using a toothbrush. Just ain't worth it.

[doitright]

Hi Linelle :)

I see a huge differance, but see it does need more work. Here's a link to Cathedral Stone which offers the D/2. It is most effective if the surface is totally dry, and can remain dry for at least a day. Do not dilute. Allow the product to saturate the surface. Do not rinse.

http://www.cathedralstone.com/d2.html

I was observing in your original photo the appearance of a sprinkler valve going into the patio from the hose bib. Is it possible that this has sprung a leak under the patio, causing excessive moisture? :shades:

[linelle]

John, glad you could see some difference! Although it still needs work, it doesn't gross me out like before. I looked at the Cathedral Stone site and D/2 sounds good. Is it sold through local distributors? I couldn't find any mention of where I might be able to buy it locally.

You are a good sleuth to spot the sprinkler valve. To the best of my knowledge it hasn't worked in years. In any event, I turned the sprinklers off completely sometime in October and haven't used them since. However, now that it's the end of May, I'll set them up to automatically water the lawn in the front of the house. Since all plants in the back yard are in borders or planters, I water by hand. However, I'm guessing that the newer (and blacker) tile, south of the picnic table legs was originally a small lawn that was on part of the sprinkler system. Hmmm. I guess I can ask my yard service to take a look and see if anything has been leaking over the years.

I really appreciate your help and good ideas. This is one awesome group.

[doitright]

Hi Linelle :)

If you're not using that sprinkler system that goes under the patio, I highly recommend that you have it disconnected.

The D/2 is sold directly through Cathedral Stone. If you have a problem ordering, I'll order it for you. I only ask for one thing in return, SHOW ME THE MONEY! :D

[linelle]

A little over a year ago I posted some pics of my very blackened terra cotta tiles in the backyard. I cleaned them with some bleach and they improved a little. This past winter was very wet and they again looked awful. The bleach water hardly budged the gunk. I really started hating my backyard, esp. with its ugly deck. Until this weekend...

Two words: pressure wash

I had my deck pressure washed to remove an old dark stain. After they were done, the guys called me out and pointed to a few tiles which they had cleaned. Did I want to do the entire patio? It was over my budget, but I was floored by the results. The stuff came off effortlessly! I still have to treat my deck next weekend, but I feel like I got a new backyard. Really a huge bang for the buck.

Before:

http://johnbridge.com/vbulletin/attachment.php?attachmentid=19808&stc=1

After:

http://johnbridge.com/vbulletin/attachment.php?attachmentid=19809&stc=1

[doitright]

Hi Linelle :)

Looks outstanding! :tup2)

Do you know what they used, or the procedure? :shades:

[linelle]

John, as far as I could tell, it was just water under pressure. The dirt and grunge and black stains really just melted away. Afterwards he went over it with a light spray from a pump he carried, probably just bleach, by the smell of it. On the deck he used a citrus product to loosen the dark stain, then the pressure wash. He didn't prep the tiles with anything. I was totally blown away.

[doitright]

Thanks Linelle :)

Are you going to seal them?

[linelle]

Well, I hadn't planned on it. But neither had I thought it through much. If I did, what would you recommend? How often would it have to be done? After seeing how easily the crap came off 15-year old tiles, I'm thinking, so maybe I just rent a pressure washer every year or so.