# Aging Wood and Cat Urine



## juann (Jul 16, 2016)

First things first. I'm new in the forum, so hello everyone and thanks in advance for your advices.

My project is aging raw pine stairs.

I'm on the samples phase still, but close to a final decission.

Following some advices of the knowledge base articles fom another wood website (and a lot of intuition and try-error method, 'cause there's no indication of proportions for the dilutions) I've used a solution of 8% acidity vinegar, iron sulfate (ferrous sulfate heptahydrate) and green tea (for adding tannins), to age/weather it.

The results are beautiful, but not very much what I expected. It's grey, indeed, but more a brownish or dark grey than the silver/blueish grey that show the pics of some of the users recommending this method.

So it's more something like the planks in this pic (not the doors), or darker:
http://www.woodweb.com/images_forums_public/finishing/DSC05417.JPG
(found here: http://www.woodweb.com/forum_fdse_files/finishing/776718.html)

than something like this
http://www.woodweb.com/knowledge_base_images/zp/matching_the_look_of_aged_barn_boards_1.jpg
(found here: http://www.woodweb.com/knowledge_base/Matching_the_Look_of_Aged_Barnboards.html)
http://www.woodweb.com/knowledge_base_images/bah/artificially_aging_and_weathering_wood_02.jpg
(found here: http://www.woodweb.com/knowledge_base/Artificially_Aging_and_Weathering_Wood.html)

I found that adding the tea into the mix and giving just a coat, instead of giving a coat of the tea and then, once dried, a coat of the iron sulfate+vinegar dilution, gives a lighter tone and kinda blueish shades, but never similar to the pics referred.

Before anyone suggests it i've also tried using iron acetate (vinegar+steel wool), and the results are more brown to red than grey. Also tried diluting the solution (although not incresing iron sulfate concentration, however). And used black tea isntead of green tea.

Anyway my problem now is that there are some spots where the wood has cat urine (please, don't ask… long story) and in that spots the solution does not work. As it dries, the yellow pine reapears.

Sanding has worked with some spots (not get rid at all, but wood gets some of the product) but i guess it's because they're the most superficial.

I've seen house remedies that use hydrogen peroxide, or a mix of it with dish soap and baking soda, but not tried yet 'cause I'm not sure if it will affect the absortion of the iron sulfate or even react with it, I fear the cure could be worse than the disease.

Any help is more than welcome, so…. 
¿Any ideas?


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## JoeinGa (Nov 26, 2012)

Well, you could always get the cats to pee on the entire board, at least then everything would match !


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## GR8HUNTER (Jun 13, 2016)

> Well, you could always get the cats to pee on the entire board, at least then everything would match !
> 
> 
> 
> ...


LMAO @ Joe


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## jwmalone (Jun 23, 2016)

ive seen expert floor guys damn near sand through a floor trying to get rid of pet urine stains. yours probably not that bad I would sand down past the stains if possible, if you cant I have heard of using ammonia something about making It more uniform,( cat urine has lots of ammonia) but I don't know how much truth there is to it, or if it works.


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## BobAnderton (Oct 5, 2010)

You need to use a tea made of powdered Quebracho bark to get lots of tannins into your wood. Here is a link to where to get it.


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## jwmalone (Jun 23, 2016)

I make a lot of buckskin, If you want something high in tannic acid, oak has a ton of it that's why the acorns are so bitter. Smoking buckskin over a smoldering smoky pile of oak bark is what gives buckskin its nice golden color and also made it water proof. The tannic acid can be leached out of the acorn by boiling them. Native Americans put them in a basket threw it in running water for a few days, dry it out and made flour with it. But any part of the oak tree has a high concentration of tannic acid. any type of oak. I like your cat its got attitude.


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## derrickparks57 (Apr 11, 2013)

I seriously thought the thread title said "aging wood WITH cat urine".....


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## jwmalone (Jun 23, 2016)

Me to, never heard that one must be one of those ole timer tricks lmao.


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## JBrow (Nov 18, 2015)

juann,

I am not expert on finishing wood or in the chemistry of cat urine. But your problem intrigued me so I dredged up what little I remember from my chemistry classes and did a little web research. The following is the results from my efforts, for whatever these may be worth.

It is not clear to me whether the urine spots are the result of the urine reacting with chemicals in the wood or whether the urine has produced a water insoluble barrier, or both. Unfortunately, determining why the cat urine stains reappear is difficult, if not impossible to determine. Since uric acid is a constituent of cat urine, my first guess is you are battling against this chemical. Even if the urine reacted with the wood, there is likely to be excess chemicals in the cat urine, including uric acid, remaining in the wood.

Uric acid is water insoluble and could prevent the treatment you are applying to the stair treads from penetrating into the wood, allowing stains to reappear. The three thoughts I have for removing uric acid are 1) remove the stains mechanically by sanding or scraping, 2) applying a solvent that will dissolve uric acid, and 3) introduce a chemical that will react with the uric acid to destroy the uric acid.

Since sanding is only marginally effective, probably on those areas where the urine did not penetrate deeply into the wood, some chemistry is probably required. I found no solvents that would dissolve uric acid. I did find three references for breaking down uric acid into water soluble compounds. These chemical approaches would require applying the reactive chemical to the urine stain, possibly neutralizing the applied reactive chemical, and dissolving the by-products in warm water. Some soaking periods would probably be required to ensure penetration and removal of the various chemicals.

Using a sample board of pine, ideally the same species as the stair treads could show how any series of chemistry based steps might affect the end results. Applying the chemical steps and then the final stair tread finishing treatment would highlight any problems with the technique. Ideally the sample board would also have cat urine stains, but a cooperative cat agreeing to pee on the sample board would be required. Since herding cats is difficult at best, I doubt the feline will cooperate; but I still think a sample board even without cat urine stains would be good.

One method is to soak the stain with an enzyme that will alter the uric acid. A product I found that claims to use enzymatic action for cat urine stain removal is Urine Off Odour & Stain Remover. It is at…

http://www.biopronz.co.nz/urine-off/42-urine-off.html

A second reference stated that sodium bicarbonate (baking soda) will react with uric acid, converting it to water soluble salts. Baking soda dissolved in warm water soaked into the stain may therefore work. Subsequent warm water soaks could then pull out the excess baking soda and salts produced by the baking soda. This approach came to mind from this source…

http://archinte.jamanetwork.com/article.aspx?articleid=654031

The third reference would be the most noxious approach. Destroying the uric acid can evidently result from the application of ammonium hydroxide (household ammonia - but without additives such as those that seek to mask the odor). Two of the four products of this chemical reaction are allantoin and urea, both of which are soluble in warm water. I did not find the other products of the reaction, so I cannot say whether these additional by-products are water soluble. After an application of ammonia, I would feel better by neutralizing the ammonia with vinegar. However caution is in order since vinegar plus ammonium hydroxide produces ammonia gas, good ventilation and a chemical filter mask are required. Neutralizing would be followed by warm water to remove any residue. This abstract suggests ammonia could work…

http://www.ncbi.nlm.nih.gov/pubmed/3180423

I saw no references to hydrogen peroxide and its effect on uric acid. Since it is an oxidizing agent, it may also work.


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## jwmalone (Jun 23, 2016)

So there may have been some science behind that ammonia thing I heard, old timers are usually right. Thanks Jbrown I'm going to book mark that stuff for future reference.


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## juann (Jul 16, 2016)

> Well, you could always get the cats to pee on the entire board, at least then everything would match !
> - JoeinGa


Oh, Joe,I'm so sorry,., I think you've logged in into the wrong forum…. you shoud try lumberjokes!! ;P


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## juann (Jul 16, 2016)

Thanks jwmalone and BobAnderton.

Dunno if the not-so-grey coloring is because of the lack of tannins, but could be.

I just made the tests with something i had in hand, i mean at home.

Anyway a really good way to add tannins is to give a coat of cremor tartaric (tartaric acid) diluted in water. Cremor tartaric is a byproduct of wine production (hence the tannins) widely used in cooking, so you can find food-grade cremor in vinoteques or cooking-specialized stores.

regards


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## juann (Jul 16, 2016)

WOW JBrow… that's quite an answer.

I had already found diverse references about the two first methods suggested, but not the third.

I've seen baking soda mixed both with warm water or hydrogen peroxide and some do add dish soap to the mix.

Thanks for your thorough answer.

PD. Making a cat to pee on anything is just a piece of cake. It only requires you to truly desire him/her not to do it.


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