# Mold Growing on Hardwood Floors



## PatrickBateman (Jun 8, 2011)

I was wondering if anyone could offer some advice on dealing with mold growing on hardwood floors. My wife and I recently got a Chinese Shar-Pei puppy and, as most Shar-Pei do, he makes a HUGE mess when he drinks water. We have been using a rubber mat to catch some of the water but it doesn't seem to do much good because water ends up under it and I think it creates an ever worse problem. 

We choose the location of the water bowl because we could tell it was where the previous tenants had their dog's bowl. It seemed a little darker than the rest of the hardwood but nothing bad at all. Much to our dismay, the little discoloration has quickly turned into a full-blown mold problem.

Important - We're renting. This townhouse is only temporary so we want to limit the money and effort put into it. We have to put down an extremely large pet deposit for our two dogs so we'd rather the landlord take any major repair costs out of that.

My questions are:


Is it possible for us to fix this ourselves?
Can we sand, clean, and then refinish this spot without having to refinish the entire floor? Since we're renting, we're not looking for it to be perfect, rather we just want it to look decent.
If all of this is possible, what type of finish do we use (e.g., water-based floor finish; gloss clear floor polyurethane; water-based polyurethane gloss; etc.)?

Here's what the floor looks like:






















Finally, here's the little trouble-maker:


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## PatrickBateman (Jun 8, 2011)

Holy big pictures Batman! I tried to make the images smaller but it didn't seem to work. If a moderator knows how, please feel free.


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## Blondesense (Sep 23, 2008)

Don't have an answer, but he's a cutie!


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## Floor Doc (May 29, 2010)

You are going to need to replace those boards .


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## creeper (Mar 11, 2011)

My cat sticks his paw in the dogs water bowl and digs. What a mess. So now the bowl sits inside a slightly larger square plastic tub. He still digs but all the water just flows into the underneath basin.


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## Floor Doc (May 29, 2010)

My cat sticks his paw in the bowl to , then licks his pawl . :laughing:


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## PatrickBateman (Jun 8, 2011)

Floor Doc said:


> You are going to need to replace those boards .


Really? Yikes. That doesn't sound like something I could do myself. How expensive would something like that typically be?


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## Floor Doc (May 29, 2010)

Depends on your area . anywhere from $25.00 and up a board .


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## tcleve4911 (Nov 6, 2010)

What a mess...........

Start with a paint scraper and remove as much finish and black as you can.
Apply bleach to the blackened areas. Let it work for 2-3 hours or longer if needed.
Lightly sand with 220
Stain if necessary
Apply 3 coats oil based polyurethane.
Steel wool to blend into surrounding flooring.


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## oh'mike (Sep 18, 2009)

That's not mold---Red Oak contains tanic acid--when exposed to water it will turn black---nature of the wood--
Red oak does not tolerate water---your finish is about shot---Consider refinishing the floors.

Use 3 coats----


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## tcleve4911 (Nov 6, 2010)

oh'mike said:


> Consider refinishing the floors.


They're renting...........


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## oh'mike (Sep 18, 2009)

tcleve4911 said:


> What a mess...........
> 
> Start with a paint scraper and remove as much finish and black as you can.
> Apply bleach to the blackened areas. Let it work for 2-3 hours or longer if needed.
> ...


As a renter---this is very good for your situation!--Mike---


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## chrisn (Dec 23, 2007)

oh'mike said:


> That's not mold---Red Oak contains tanic acid--when exposed to water it will turn black---nature of the wood--
> Red oak does not tolerate water---your finish is about shot---Consider refinishing the floors.
> 
> Use 3 coats----


Well. Mike, I am glad someone here has some knowledge. You would think any floor guy would know this, even I knew this.


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## ratherbefishin' (Jun 16, 2007)

chrisn said:


> Well. Mike, I am glad someone here has some knowledge. You would think any floor guy would know this, even I knew this.


Yeah, but did you guys forget that oak tannins can usually be bleached out with oxalic acid?:wink:


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## oh'mike (Sep 18, 2009)

ratherbefishin' said:


> Yeah, but did you guys forget that oak tannins can usually be bleached out with oxalic acid?:wink:


Did you ever try that? 

I had rotten luck---turned the wood a nasty yellow---I may have over done it----


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## Jackofall1 (Dec 5, 2010)

I remember many many years ago, at least twice a year, I had to help in the "Redoing" of the hardwood floors in the house I grew up in, if I remember correctly this also took care of water stains.

Varsol, fine steel wool and Johnson's paste wax. 

Pour varsol on the effected area and scour with fine steel wool, once clean apply wax. Now with the poly finishes, I would imagine it would be pour varsol on the effected area and scour with fine steel wool, stain to match color and finish with poly. Then scour with find steel wool to match sheen.

Mark


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## epson (Jul 28, 2010)

I did exactly as tcleve4911 outlined above except I used a brush to apply the polyurethane and it blended very nicely with the surrounding floor.


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## PatrickBateman (Jun 8, 2011)

oh'mike said:


> That's not mold---Red Oak contains tanic acid--when exposed to water it will turn black---nature of the wood--
> Red oak does not tolerate water---your finish is about shot---Consider refinishing the floors.
> 
> Use 3 coats----


I'm not sure what this means. So, the hardwood floor is red oak, which contains tanic acid and, therefore, will turn black when exposed to water? Once it's exposed to water, does it turn black permanently?


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## oh'mike (Sep 18, 2009)

Yep---that's why you need to sand as much as you dare--then oxalic acid used sparingly to lighten the stain.

I will be removing a few planks when I sand my floors as there a some boards where the stain will not sand out.


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## PatrickBateman (Jun 8, 2011)

oh'mike said:


> Yep---that's why you need to sand as much as you dare--then oxalic acid used sparingly to lighten the stain.
> 
> I will be removing a few planks when I sand my floors as there a some boards where the stain will not sand out.


I see. Following tcleve4911's instructions, would I apply the oxalic acid after I lightly sand with 220? Also, do I need to make sure the oil-based polyurethane matches the floor's color? Sorry to sound so clueless, but, I'm pretty clueless. I've never even thought about messing with this stuff.

Thanks for the quick responses and suggestions everyone. :thumbsup:


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## oh'mike (Sep 18, 2009)

oxalic acid is sold in paint stores and is usually a powder---mixed as you need it---Very mild and safe to use.

The new work will be lighter colored than the old---a little bit of purital pine stain may be needed to add the missing 'patina'.--Mike---


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## ratherbefishin' (Jun 16, 2007)

oh'mike said:


> Did you ever try that?
> 
> I had rotten luck---turned the wood a nasty yellow---I may have over done it----


Not sure what might have happened there, Mike. I've used it mostly on teak brightwork and oak furniture and haven't seen that particular problem. The most common thing I've run into is that it isn't always strong enough and I have to do repeat applications or go to a two part bleach.


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## PatrickBateman (Jun 8, 2011)

oh'mike said:


> oxalic acid is sold in paint stores and is usually a powder---mixed as you need it---Very mild and safe to use.
> 
> The new work will be lighter colored than the old---a little bit of purital pine stain may be needed to add the missing 'patina'.--Mike---


Thanks Mike! You're a real life-saver. I'm headed to Lowe's & Paint Store tomorrow and I'll let you guys know how it goes.


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## chrisn (Dec 23, 2007)

oh'mike said:


> Yep---that's why you need to sand as much as you dare--then oxalic acid used sparingly to lighten the stain.
> 
> I will be removing a few planks when I sand my floors as there a some boards where the stain will not sand out.


 
Just flip em over( I am sure you thought of this but many HO would not and are out buying new wood):wink:


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## oh'mike (Sep 18, 2009)

That wouldn't work,as it is tongue and groove and the planks will be destroyed in the removal---
And the backs aren't flat---

(besides---standard oak flooring is so cheap that there is little cost in using fresh clean product)


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## tcleve4911 (Nov 6, 2010)

ratherbefishin' said:


> Yeah, but did you guys forget that oak tannins can usually be bleached out with oxalic acid?:wink:


Good tip!!!!
Where do you buy that?????
Is it called something else? Like Tannin Bomb??? get it?? ....sorry.....:jester:


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## ratherbefishin' (Jun 16, 2007)

tcleve4911 said:


> Good tip!!!!
> Where do you buy that?????
> Is it called something else? Like Tannin Bomb??? get it?? ....sorry.....:jester:


Ewwww....that was bad!:laughing::laughing::laughing:
Now I know who took my Alvin and the Chipmunks Christmas CD.......


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## PatrickBateman (Jun 8, 2011)

Here's the polyurethane I got from Lowe's:










Is that right?


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## oh'mike (Sep 18, 2009)

That will work just fine----


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## PatrickBateman (Jun 8, 2011)

oh'mike said:


> That will work just fine----


Awesome! Thanks Mike!


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## PatrickBateman (Jun 8, 2011)

Got a little busy but I've finally gotten time to work on the floor. Here's what it looks like after using the oxalic acid. I'm pretty sure that's as light as it's going to get so I'm about to apply the polyurethane. Do I need to do anything else before that?


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## clairedemonstra (Dec 2, 2011)

Hi there - have you tried a stain remover called 1000+ Stain Remover? It is amazing and works especially well on hardwood floors. Apply directly, scrub with one of those little sponges that are yellow on one side and green on the other - then spray water from a spray bottle and wipe away residue with an old cloth. 1000+ works on mold as well as stains on wood flooring. At least you would have a *clean* surface in which to try to re-stain (ask hardware personnel - I am sure there is a stain you can use that would make it look much much better - without replacing all the boards! Check out this amazing (I demo it part-time and use it on everything!) at www.1000Plus.ca Good Luck - let us know how you do!


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## PatrickBateman (Jun 8, 2011)

Just wanted to bump this thread to see if I could get some feedback. Tried private messaging oh'mike but I'm not allowed to because I don't have 20 posts yet. If anyone could give Mike a shout for me it would be much appreciated.


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## oh'mike (Sep 18, 2009)

Patrick--I'm back----You haven't sanded the area yet---do you have a pad sander or a random orbit?

--For a good look---sand the affected area until all the old finish is off the boards---A little skill and you can confine the sanding to the edge of the boards--so you don't have a board that has new and old color-

If the sanding leaves to much of the black staining---use the acid on those spots once more--then sand again--

I'd start the sanding with 80 or 100 grit---then 150 for the final before color---

That floor is 'natural' but has mellowed with age----An oil based polly will help match that color--but might need a bit of stain to replace the patina that you sanded off---I think Ipswitch Pine by Minwax should be close--(do check the color chart--I am dismal at remembering names--my greatest failing and embarrassment,actually)

Keep me tuned in----there are others here with lots of woodworking and finishing experience---Others will offer suggestions,too.---Mike----


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## oh'mike (Sep 18, 2009)

Just a tip----Go to 'introductions' and welcome some new members----you can have your PM privileges in a mater of minutes---and make a few newbies feel good at the same time---M--


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## PatrickBateman (Jun 8, 2011)

oh'mike said:


> Patrick--I'm back----You haven't sanded the area yet---do you have a pad sander or a random orbit?
> 
> --For a good look---sand the affected area until all the old finish is off the boards---A little skill and you can confine the sanding to the edge of the boards--so you don't have a board that has new and old color-
> 
> ...


Thanks for getting back to me Mike. I stripped as much of the finish off as I could and sanded as best I could, then applied several rounds of the oxalic acid. I don't have a pad sander or a random orbit so I've had to do it by hand. Today I picked up a sanding block so that should make sanding a little easier. 

Based on the above pictures, do you think I need to sand more, then apply more oxalic acid?


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## PatrickBateman (Jun 8, 2011)

oh'mike said:


> Just a tip----Go to 'introductions' and welcome some new members----you can have your PM privileges in a mater of minutes---and make a few newbies feel good at the same time---M--


Great idea! I never even thought of that.


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## oh'mike (Sep 18, 2009)

If you need to stain in order to add some color --the wood must be clean---so sanding or scraping will be needed for that--I've got a good hand with a cabinet scraper---but that's kind of a lost art--

The finish on the whole floor is going bad---so your 'fix' might look nicer than the rest of the floor--

Sand as well as you can---a razor blade can be used as a scraper for corners--then try your finishes--


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## PatrickBateman (Jun 8, 2011)

oh'mike said:


> If you need to stain in order to add some color --the wood must be clean---so sanding or scraping will be needed for that--I've got a good hand with a cabinet scraper---but that's kind of a lost art--
> 
> The finish on the whole floor is going bad---so your 'fix' might look nicer than the rest of the floor--
> 
> Sand as well as you can---a razor blade can be used as a scraper for corners--then try your finishes--


Will do. Thanks again Mike.


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