# Forum Home Renovation Plumbing  What causes a chrome floor waste to turn black???

## renov8or

A neighbour partly renovated her bathroom a year ago, not long after it had been fully renovated by the previous owner. She had the floor retiled including a new waste as the existing (new) one had turned black. A few months after that she noticed the new waste she had installed turned black as well. I renovated my own bathroom earlier in the year and a few months ago I noticed my chrome flloor waste doing the same - but only the insert, the fixed part was ok. After a bit of effort I cleaned it up, polished it with car polish and put some vegie oil on the underside and between the slits hoping this may help. This worked for a while but is going black again. It is much more than tarnish, hard to completely remove with a cream cleanser and rag. I don't have the same problem in the shower, so obviously the daily washing is the difference. 
So what causes this? Is it the moisture/vapour from grey water water sitting in the S bend, which does get flushed from above when water from the basin drains into the pipe above the water level? How do you stop it. 
Thanks

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## stevoh741

mine are black too however the ones in the shower (same brand, installed same time) are still clean too (4yrs use). That shot my idea of the chrome wearing off from foot traffic. I too would be very interested in an answer. Next time I plan to use the FW that you tile the top of just leaving a square perimeter for water to go down. Looks better and wont turn black.

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## Ken-67

Are they chrome on solid brass?

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## renov8or

I assume they are chrome plated cast brass. The underside and slotted are rough - as in cast! See photos. I also noticed the same problem in a $4 mill property a week ago, so don't feel to bad. I bought mine at Bunnings, not sure if it was Brasshards brand or another -  they all look like that are made the same way. 
I have just taken some photos, see attached. It does not look too bad but was worse last time before cleaning. Once tarnished/stained or rusting -  what ever it does, it is hard to reverse. What I did notice was that the underside was moist -from evaporation of the water in the trap immediately below (the floor had not been wet). The staining on the waste is similar to rust, particularly on the underside, but more tarnished on top. Both wastes have a trap underneath so there is always moisture present, but the shower is only about 40 mm whereas the main waste is about 80 mm. Also the shower trap would have much cleaner water in it due to greater amount of water in relation to soap than what comes from hand basin drain. I suspect the grey water/or just water below is the problem, but how to overcome it. Brushing on some oil on the underside and polishing the top seemed to help fend off the problem for a while last time. So, the cause seems obvious, just need the remedy. I can see the benefits of those cheap chrome plated plastic ones!  First photo is shower waste, remaining 3 are of main floor waste. You can see how the shower is much less ....rusted???

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## takai

Looks like galvanic corrosion to me. Either that or acidic corrosion.

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## Ken-67

From the pictures, the back looks to me more like galvanized cast iron, but that might be the lighting. You also seem to be getting discoloured flecks showing in the top, which also suggests the submetal is not brass. Can you put a file cut into the back? If it is brass, it's not going to hurt it. You will have to go deep enough in case it is only brass plated under the chrome.

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## chrisp

The brown is indicating iron as a base metal (I'd expect to see green if it was a copper based metal).  See if a magnet sticks to it as a non-destructive test. 
The spotty nature seems to indicate that the plating is porous or just not thick enough. 
Why is the shower one good/better than the other?  I can only guess that the 'other' one might be exposed to harsher chemicals (bleach?) more often, or maybe the soap used in the shower is somewhat more protective?

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## renov8or

Thanks guys 
I just tried a fridge magnet on it and it does not show any attraction - even tried sticking it to the waste grate when held upside down. I will try a stronger magnet and a file on it tomorrow. 
The shower waste is exposed to soap (cake) and shampoo - body oil may be a relevant fact in the equation also. However there is a large amount of fresh water constantly running in relation to anything else. The dry  floor waste (the problem) is over the main trap  - the only regular flow into this is from the hand basin - the same soap (cake), toothpaste and shaving cream. Any cleaners used are the same for both. The shower waste has water running over it daily, the dry floor waste rarely has water flow over it. Both wastes were bought at the same time, probably came from the same batch. The entire waste - both sections, are fully chromed. 
Plus....keep in mind that a neighbour has the same problem with a recently installed waste, which replaced one fitted a couple of years prior to that with the same problem. Same brand, same batch ...I don't think so Tim!!

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## stevoh741

Here are mine. Shower clean (apart from the wifeys hair) FW, only 600mm away black. Installed same time, go figure?

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## chrisp

It is an interesting problem.  Chemistry isn't my strong suit by far, but if you do a web search for terms such as _chlorine nickel chrome corrosion_, it turns up a lot of similar discussion. 
It seems that chlorine (and many other -"ines") can attack chrome/nickel plating.  It various sources debate whether it is waterborne or the cleaning agents used. 
Here is a theory - maybe it is the cleaning agent (which contains chlorine).  It gets used on both wastes.  On the shower one (which is used regularly), the chemical is washed away and diluted.  In the floor waste, the chemical remains in the trap and chlorine fumes continue to attack the plating.

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## renov8or

Tested my waste grille with heavy magnet - no attraction. Filed away some chrome and beyond - brass. There is a "B" laser inscribed on the top which I assume refers to Brasshards  brand. 
The grey water which evaporates from the trap appears to be the problem. My bathroom floor only gets a wipe over with a damp sponge and Handy Andy, rarely needs a scrub and water sloshed over it. In my last photo of the waste sitting on the bath mat, you would swear that it is so rusted that the chrome would flake off, but when cleaned with Gumpsion it removes most of the "rust appearance" and has not eaten into the chrome??? 
I can see the only remedy is to construct some sort of flap into the neck of the drain pipe above the last inflow from the hand basin so as to reduce the amount of evaporation reaching the waste grill, or a piece of Styrofoam or cork which is a loose fit and will float on the surface of the water reducing the surface area, but allow water to pass over it. 
Stevo - do you have a greater surface area of water in your floor trap compared to your shower trap. Does my situation mirror yours exactly when considering all I have detailed?

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## Ken-67

I've dug out 50-year-old grates in better condition than this. If I were you, I would contact Brasshard directly. Send pictures and details of your problem, and see if they can offer a solution. On their web page they claim a policy of 'only supplying the highest quality pr4oducts'

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## Bedford

I don't know why it's happening but I've never seen it with the chrome plastic wastes.  
I wonder if one of these Plastec Australia - Innovative Plumbing Solutions - Plastic Grates could be interchanged with the current fitting?

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## Master Splinter

Going out on a limb...it could be a slightly too-thin layer of chrome, which is ever so slightly porous, which is letting (something...possibly chlorides or sulphides) attack the zinc..I think both chlorides and sulphides of zinc have a black corrosion stage (somewhere in their atomic makeup).  Normally the zinc is protected by a layer of zinc (carbonate????) that forms on contact with air, but it also needs moisture to form in a stable way. (cf white corrosion on galvanised materials in storage).

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## anawanahuanana

Glad I'm not the only one with this problem!
My floor waste grate is exactly the same design, and also has the same problem. I replaced the removable centre part a year or 2 ago as it had gone black (but not the fixed surround part) and now the new one is just the same. Interesting that the fixed surround does not discolour though. We only clean our floors with water with a bit of cleaning vinegar mixed in. No bleach.

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## renov8or

I have spoken to Brasshards who offered to replace the grille, but as the main issue is identifying the cause and hopefully the remedy (for all those other people affected also), I have forwarded the link to this thread. I will post any feedback. I was advised that they are now using a heavier coating of chrome - since mine was bought.

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## BRADFORD

I think this problem is caused by sewer gasses (methane?) coming back up the floor waste. They are quite corrosive.
Because the floor does not have a regular flow of water, the water seal in the trap dries out and alows the gasses to flow back from the sewer.
You may be able to stop it by tipping some water down the waste say once a week.
Older houses (in WA at least) have the floor waste running outside with a flap on the end to stop vermin etc. I've always thought that was a better idea.

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## renov8or

Just an update for those who may have been wondering what the outcome was after Brasshards sent me new wastes - no different! Brasshards were confident this would solve the problem. The new ones did have a thicker coating of chrome as advised, and evident on the cast underside. However 3 months on the main floor waste is starting to get the same tarnished look as described at the start of this thread. Seems no solution other than to keep polishing it. The chrome plated plastic ones I have always thought were cheap and nasty are now looking pretty sweet.  
(BTW Bradford, my main floor waste is above the trap which has water enter from the vanity basin - so is flushed frequently and no gases from the sewer enter.)

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## BRADFORD

Interesting, looks like plastic in some applications is best after all.

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