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Question DetailsAsked on 4/4/2014

We have a glass block shower. There is green inside the grout. What do I do?

The shower is made of standard large glass block. The grout is fine to the eye on the surface, but when you look through the block, the internal grout is green in a very large section of the shower. Can you remove the grout between two block without the wall caving in? Do we have to tear out the whole thing? I assume it is some sort of algae, but none on the outside. Yike

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If I were able to see what you are talking about I would have a better idea if I am correct. If this is a new home to you it may very well be the color of the glass blocks you are seeing. Or it may be you added lights to the room and that is why you just noticed it. If it was algae it should show at the surface as well . Most glass block has a green tinge to it and I wonder if this si what you are seeing. Much like some clear bottles if you hold them to the right lighting.


Don

Answered 5 years ago by ContractorDon

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If you (or prior owner) use chlorine bleach products on the tile cleaning, it is possible it has permeated the joints and discolored it. However, I would bet what you are seeing is a diffusion effect on the light, like through a prism, and at the angle in and out of the block to be able to see the grout, you see only the green light. I am guessing the intensity or shade of the green varies with distance from the center, and probably also in differing outside lighting conditions, which it would not be expected to do if it was truly green.


Try shining a bright flashlight at different angles and see if it changes colors or looks white.


Also, many glass blocks ahve a bluish or greenish tint to them, which is most noticeable in oblique lighting.


If it still bothers you, I suppose you could VERY carefully scrape out a bit of the grout with a utility knife where it will not show too much on one side of a block that shows the green, and see if the edge of the grout and block is green - I would bet not.

Answered 5 years ago by LCD

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Hi Don

Thanks for your thoughts. This shower was built about 20 years ago, before glass block was current and done by a brick layer. This started to show up about 5 years ago. It does not show on the outside grout line (inside the shower). Only if you look through the glass to the inside of the grout. From what I have learned, it may be from moisture going through the grout. You do not see it from the outside of the block. Is there any way to remove grout without destroying the wall. We thought about light, but it won't work through glass. I wish I could send you a picture. I am new to Angie's list so I don't know my limitations. Again, thanks note. Lori

Answered 5 years ago by bube3

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One other thought - when they first became popular, some glass blocks had a copper flashing pre-mounted and soldered around the perimeter as a flexible waterstop, and other installers put one in if they were plain blocks - I remember doing a few that way, knowing there would be a small crack between the block and the grout because the blocks expand and contract a lot with sun exposure, and this copper strip gave some slack. This was before elastomeric caulks and such as are used today to assemble these, so what you may be seeing is copper corrosion on that copper strip. People pay thousands to get that copper patina look on their new copper roofs, so you may have just joined the ritzy elite by having it in your shower - a whole new home fashion trend at its outset ! You are a trend-setter !


Another possibility as Ben noted is a lot of those blocks have a green caste to them, so they may have copper in them, that is now corroding from moisture in the grout. Either way, there is certainly no way to remove it without tearing them out.


It should be possible to remove the grout without breaking the glass blocks with a LOT of labor, but I can just about guarantee it is cheaper to replace them. Personally, unless it is objectionable or you invite all your friends and guests to view your shower, I would not worry about it as long as the grout looks good. If the grout is porous or absorbs water (try to see if it darkens with moisture when you touch it for a few seconds with wet Q-tip) - if so, sealing the grout with grout sealer could limit the growth of the issue. Keep sealer off the blocks - will fog or haze the surface.

Answered 5 years ago by LCD

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I have a feeling LCD might have your answer. In my opinion if it were any type of mold or mildew it should be presenting itself at least in some surface areas. It could very well be the copper turning green. If that is the case you would most likely have to dismantle the wall to remedy it. If you are really concerned with this the only ay I could see to find out forsure would be to drill a hole in the grout in hidden spot to check or use a grinder to cut out a spot. Grinding out the grout would not be an option in my opinion as the wall would almost have to be dismantled to do it, which would be one option. It that is your choice it might be cheaper to buy new block to speed up the job and save on the labor.


Don

Answered 5 years ago by ContractorDon

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Votes

Thanks so much for trying. There does not appear to be copper anywhere and the blocks are totally clear. The green is in one section of the two walls. But I guess drilling a hole just for curiosity would be the next step. It's a shame to dismantle the shower, but it is kind of ugly once you know it's there, and if we ever sold the house it would be a problem, I guess.

The walls are totally fine, not compromised, but the inside grout is definitelyl a problem to the eye.

Answered 5 years ago by bube3

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Personally, I don't know I would go with the drilling method - I would be too scared that the lateral pressure of the bit in the hole would crack an adjacent block.


I would use a sharppointd scraper, or on the mechanical size, a dremel tool with abrasive disc or diamond bit to nibble away at the joint mass formaybe an inch or so length, then when down to a thin bit of grout left on each side of the joint, pop that off the block with a utility knife or razor blade to expose theblock and look at that contacting piece of grout.


One other thing you coulddo is contact PPG - probably the largest manufacturerof glass block, with your issue and see what they say.

Answered 5 years ago by LCD

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If there is a tiny leak in the grout, it could be algae from your water supply. A microscopic bit of algae would eventually grow enough to become visible.

Answered 4 years ago by Guest_9067864

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I have the exact same problem, did you ever get figure out what to do?

Answered 3 years ago by Charlie2002




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