# Can this floor be salvaged?



## IndyRyan (Sep 10, 2010)

The house I'm buying has hardwood floors thoughout.  They look great... with the exception of black spots around every nail in the floor.  I'm not sure what it is or how deep it goes.  I just wonder if it's worth trying to refinish them.


----------



## Nestor_Kelebay (Sep 11, 2010)

Indy Ryan:

Well, I guess it depends on which reference material you choose to believe.

First, the facts:

That black stain around each nail is something called "Iron Gall Ink", and it's produced whenever the tannins in plants reacts with iron (from the nails).  Tannins are common in plants.  When you bite down on a grape seed, the astringent taste is due to tannins in the seed.  The varying degree of yellow, red and brown colour in red oak, redwood, southern yellow pine, cedar and mahogony is due to tannins in the wood.  Tannins are extremely soluble in water, and in fact tea gets much of it's reddish colour from the tannins in tea leaves.

Tannins in turn are "phenols" or "polyphenols".  A "phenol" is just a benzene ring with  at least one hydroxyl group attached to it, like this:






or





(which is a chemical called "gallic acid")

And, if a molecule contains more than one phenol unit, it's called a "polyphenol" like tannic acid:






(Note that tannic acid is really just a central sugar (glucose)molecule with four gallic acid molecules hanging around.)

Well, it turns out that most plants have a lot of polyphenols in them.  In fact, it's estimated that about half the mass of a tree's leaf consists of polyphenols.

And, all of those polyphenols are collectively called "tannins".  That word "tannin" comes from the fact that these chemicals were used intensively in the leather *tanning* industry in the 18 and 1900's.

Tannin - Wikipedia, the free encyclopedia

It turns out that some tannins react with iron or iron ions to form a dark precipitate which is insoluble in water and was used for centuries as writing ink.  That precipitate is called "iron gall ink".  It was a very popular ink in the middle ages because it is very difficult to remove from paper.  In fact, the only way it could be removed from paper was to scrape off the paper containing the ink.  At a time when most people couldn't read or write, forgery was a popular way to cheat someone out of house and home by creating false wills, deeds or other documents.  Consequently the permanence of iron gall ink made it a favourite choice of notaries, barristers and government officials.

So, on the one hand, most references will tell you to give up on trying to remove iron gall ink from wood or anything else.

However, I am aware of one very reliable reference that says that you can chemically change iron gall ink into a clear salt by reacting it with phosphoric acid or oxalic acid:

Go to the Canadian Wood Council's web site at:

Welcome to CWC

Then hover over the "Publications" link and click on "PDF Publications".

Then, in the "Durability" section, click on the PDF file entitled: "Discolouration on Wood Products: Causes and Implications"

That publication was produced by "Forintek", which is a University of British Columbia research group that investigates problems and recommends solutions for the forest products industry in Canada.

On page 5 of that 8 page pdf file, it talks about non-fungal discolourations on wood, and says:

*"Lumber is sometimes discolored with ironstain &#8211; this happens when iron particles react with phenolic chemicals in the wood, leaving behind black iron tannates (a common ink pigment). Iron can come from steel wool, filings, lubricants containing metal fines, from invisible iron particles where the wood has rubbed on steel rollers or chains, or even from airborne particles, for example from the brakes or from the wheel-on-rail friction of railway cars (called travel stain).  Diagnosing iron stain can usually be done by spotting a dilute (~3%) phosphoric or oxalic acid on the stained part; the acid breaks down the iron tannate into colorless iron salts, and the ironstain is decolorised."*

What they're saying is that you can tell if a black discolouration on wood is iron gall ink by treating it with a weak concentration of either phosphoric acid or oxalic acid.  If it's iron gall ink, the acid will break the iron tannates down to a colourless salt, thereby removing the stain.

Now, phosphoric acid is commonly found in bathroom and toilet bowl cleaners.  That's because it cuts through soap scum like a hot knife through butter, but won't attack chrome.  Toilet bowl cleaners will also use phosphoric acid as the active ingredient because it's strong enough to dissolve anything you're likely to find in a toilet bowl while still being relatively mild on both your hands and the environment.  The problem with using a toilet bowl cleaner is that it will be gelled so that the acid sticks to the sides of the bowl better and doesn't drain off, and that same gelling will also prevent the acid from being wicked into the wood, which is what you need it to do to get at the iron tannates that are causing the black stain.  I'd phone any place listed in your yellow pages under "Janitorial Equipment & Supplies" and ask if they sell a non-gelled phosphoric acid based bathroom cleaner.  I know that Buckeye products makes a non-gelled bathroom cleaner called "Sparkle" that's about 40 percent phosphoric acid.  Sparkle can be diluted with 12.75  (twelve and three quarters) parts water to make a 3 percent phosphoric acid solution.

Oxalic acid is commonly found in hardware stores.  It's sold as the product called "wood bleach" because it's used to remove the yellowing of the wood that occurs when it's exposed to the Sun outdoors.

Maybe ask the home owner if you can try phosphoric acid or oxalic acid on some of those nail holes to see if you can remove the black stains around them.  But, maybe don't tell him/her what you used if it works because he/she may want more for the house if they know that the stains on the hardwood floor can be removed.

Hope this helps you.


----------



## Nestor_Kelebay (Sep 11, 2010)

here's more on iron gall ink:

http://en.wikipedia.org/wiki/Iron_gall_ink


----------



## gatorfan (Sep 11, 2010)

IndyRyan said:


> The house I'm buying has hardwood floors thoughout.  They look great... with the exception of black spots around every nail in the floor.  I'm not sure what it is or how deep it goes.  I just wonder if it's worth trying to refinish them.


Just my opinion, but I wouldn't touch those floors.  I think the look is awesome and truly vintage.  I would try to clean up any scuffs (steam?) and just poly right over it, leaving any minor dings and the iron gall ink as-is.  Obviously if there are holes or deep cracks you would have to fix those. 

If you sand away all of the character, it's going to look like any other new house with freshly laid, boring floors.  If you choose the right poly, it should be effectively self-leveling, so you'll still get a smooth, clean floor that will look great and be easy to clean without losing all of the character.

Again, just my 2c.

Matt

P.S. I can't get over how perfectly straight the nail lines are.  That's craftsmanship!


----------



## IndyRyan (Sep 11, 2010)

Nestor - Thanks!  That's got to be the most thorough answer I've ever gotten on an internet message board.  You may well have just saved me countless hours and money.  I imagine I would've spent a great deal of time trying to sand that off.

  The house is an REO, so I don't have to worry about the owners letting me try it out on a couple of spots.  I'll try to get in there tomorrow and test it out.

gatorfan - I hadn't really considered the character of the house...  in any of my remodeling plans.  That's probably something I need to spend more time thinking about.  This is my first real remodel.  I've done work here and there on previous homes, but this is the first one that I've really gone for the full overhaul.  I just want to make sure the decisions I make are the ones that will give it the best shot to sell a few years down the road when I move on to the next one.


----------



## Nestor_Kelebay (Sep 11, 2010)

IndyRyan:

I've never refinished a hardwood floor, but my understanding is that you can't refinish the floor once the nail heads start becoming exposed.  At that point, it's time to replace the hardwood rather than refinish.  In your case, you're starting with a floor where the nail heads are already exposed.

Have you ever refinished a hardwood floor with the nail heads sticking up like they are on this floor, and what were the results?


----------



## IndyRyan (Sep 13, 2010)

Nestor_Kelebay said:


> Have you ever refinished a hardwood floor with the nail heads sticking up like they are on this floor, and what were the results?


I haven't, but the floor is in pretty good shape.  I really don't think it needs much sanding, especially if I go with a little bit of a darker stain.  I think it's worth a shot, at least.


----------



## woodgirl (Sep 13, 2010)

gatorfan said:


> Just my opinion, but I wouldn't touch those floors.  I think the look is awesome and truly vintage.  I would try to clean up any scuffs (steam?) and just poly right over it, leaving any minor dings and the iron gall ink as-is.  Obviously if there are holes or deep cracks you would have to fix those.
> 
> If you sand away all of the character, it's going to look like any other new house with freshly laid, boring floors.



I totally agree with gatorfan, anyone can go to Home Depot and buy a hardwood floor.  You just can't buy that kind of character!  With just a light sanding and proper finish, that floor will be stunning!  I can e-mail you a link to a good source for wood floor cleaning and refinishing complete with videos.

Happy remodeling!


----------



## woodgirl (Sep 13, 2010)

gatorfan said:


> Just my opinion, but I wouldn't touch those floors.  I think the look is awesome and truly vintage.  .....
> 
> If you sand away all of the character, it's going to look like any other new house with freshly laid, boring floors.



I agree with gatorfan, you just cant match that character with a "New" wood product.  This look is very popular, especially now when everyone is recycling.  A very light sanding and the proper finish is all that floor needs.  There's a lot of information (including videos) at Paintsource.net They may even have a product to remove the dark spots if you do plan on going that route.  you will definitely add character, charm and value to the house if you KEEP the floors!  Good luck and happy re-modeling!


----------



## 1victorianfarmhouse (Sep 14, 2010)

I would agree with the others about the flooring having lots of character.  Reminds me of my house.  The light wooden flooring on top of the initial flooring boards has some areas with black spots around like Nestor describes.  The floor was sanded and refinished and has a great look.  The building inspectors when I had the house inspected before buying were talking about how great it is to see such work, and nothing was said about what would be called imperfections with today's manufactured floorings.  

vince


----------



## woodgirl (Sep 14, 2010)

I e-mailed my friend at Paintsource.net and here's what he had to say...Just another opinion:

"That is an interesting circumstance, and a solid answer. Oxallic acid is sold as Wood Brightener where deck or log home stains are sold. Most paint stores carry an oxalic acid brightener. I agree with the posts, that is a lot of tedious work, and gain is questionable to try and remove. The look could be simulated or enhanced as well,. I know craftsmen who will put thinned black paint or stain to get that effect, even on some old restorations. If it is a stain or pigment,  and not tannin, then the acids will likely be ineffective.

I think the challenge is how different every project is. There are so many articles you could write with your experience. My main expertise is with the finishes themselves. My main thing to get across is that Waterlox is such a superior choice for character wood like that. You have to sand both oil and water-based polyurethanes for recoat, they look like plastic, and they show scratches tremendously (dogs and kids). Waterlox is the easiest to maintain and rejuvenate when needed, looks good longer, and requires no sanding for future recoat.

I will be happy to help any of your clients evaluate finish options. Please link to any information on our site:

Finishing Guides

My writing is not so polished, but here is our blog:

PaintSource Blog

Waterlox Blog

Please tell Steve hey from us.

All the best.

Doug Wilson

PaintSource.net


----------



## IndyRyan (Sep 17, 2010)

Thanks woodgirl.  I think I have come down on the side of leaving the black spots alone.  If nothing else, it will save me time that I can spend in other areas of the house.


----------



## woodgirl (Sep 17, 2010)

good idea...you should check out the waterlox...we use it all the time and recommend it to all of our customers.  If you decide to go with it, I may be able to get you a discount.  Please post photos as you go along


----------



## IndyRyan (Sep 17, 2010)

woodgirl said:


> good idea...you should check out the waterlox...we use it all the time and recommend it to all of our customers.  If you decide to go with it, I may be able to get you a discount.  Please post photos as you go along



I love it. 

Is there stain mixed with the Waterlox used in the Finishing Guide videos?


----------



## woodgirl (Sep 17, 2010)

Not sure...I know it has tung oil in it which I absolutely love.  I know for sure you can _mix_ stain with it because my boss does it all the time.  You should give Doug a call.  He is an expert at wood finishing 1-866-278-9831...super nice guy too!


----------



## handyguys (Sep 17, 2010)

I don't remember that Waterlox is rated for floors. make sure you confirm before using that.

Also, those floors could be restored if you wanted. They would be sanded. The nails would be set when the heads begin to shine (shiners). Those floors were all face nailed. They are in my parents house. Those spots may be rust. Yes, oxolic acid would be used after sanding to lighten around the nails. Dark stains to try and blend the surrounding wood would be pretty drastic in my opinion.

Good luck


----------



## FLGarageDoors (Sep 20, 2010)

gatorfan said:


> JObviously if there are holes or deep cracks you would have to fix those.



What's a good product to use for filling in deep cracks on wooden flooring? My parents' house has floors like the one in the pic and there are kinda big gouges in some parts.


----------



## mabloodhound (Sep 21, 2010)

I would do as most have suggested and keep the nail stains.   Even a light sanding so a darker stain can be applied and set any nails that might be proud.   With the final finish and dark stain I think you'll be surprised at how good it looks.   And you'll have a lot more time to do other stuff.


----------



## GeneralTJWillys (Oct 6, 2010)

The stain removal subject seems to have been thoroughly covered already, but I must say, that I agree with, most others here.

Those stains give that floor a beautiful, rustic look, and IMHO, should be left there. 
I'd LOVE to have that floor in my house. A light sanding and good sealer and I'd be happy as a clam!

Whatever you or the homeowners decide......I wish you the best on the project!


----------



## floridayankee (Oct 8, 2011)

I sanded a hardwood floor many years ago and it was great because the old floor was very bad and even though the power tools I rented occasionally misfired (left burn marks, and gouges) it seemed worthwhile in the end.
I didn't think of this at the time, but wouldn't it be possible to hammar the nails in a little deeper with a nailset ? presumably it goes through the hardwood and hits the joists which aren't hardwood, right ? I remember that in a couple of cases the nail was high enough to rip my sandpaper...maybe this was avoidable...
I remember reading that you can only sand a hardwood floor so many times. The power sanders are so powerful that they might take off a lot - and then you'd have nothing left ??? How do you figure out how much wood you've got left ?
Good luck with the new house !


----------



## mabloodhound (Oct 9, 2011)

Nails should ALWAYS be set before sanding a floor.   And filler added to the holes and any other imperfections.
Remaining thickness is hard to determine unless you can get to an edge or cutout and actually measure the boards.   It isn't the power of the sanders, but the tongue and groove flooring that determines how much you can sand.
Once you get down to the groove, if you go too far, the top edge of the groove will break off and/or expose the tongue underneath.   Not a desirable look and only way to fix this is to add a new board(s).


----------



## floridayankee (Oct 10, 2011)

Very good - I forgot all about the tongue and groove. But today a different thought hit me - Why do we see all those nails ? I recall that tongue and groove
are nailed in such a way that the nail gets concealed by the next board. If all else fails then you have no choice but to nail from above. So why does this floor have lines of nails ?
I figure years later you might need to tighten a squeeky floor, and you'd hope you have access from below, so you could nail or screw from under. Maybe the ceiling is finished below ??? Or is this a floor that was never tongue and groove ?


----------

