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Fumed oak fading in light. Any source that confirms this is normal?

Doug Horgan Member

We "fumed" a white oak floor (wiped on industrial cleaning ammonia ~8%, worked perfectly at the time).
Now two years later, the clients noticed fairly serious fading of the finish. When you lift the area rugs, it's much darker under the rug, than in the exposed areas around them (first photo)--but only near the windows. On the other side of the room away from the windows, the color is the same under the rugs as around them (second photo). This happened in several rooms facing all directions, but always the fading is near windows, so it seems to be due to light exposure.
I've been googling this like mad and have found two or three articles which say that fumed oak is colorfast and doesn't fade. The clients and their designer seem to have found the same. While a few flooring guys I've asked say it is normal for some fading to take place, I am looking for a reference (book, article, web page) or authoritative expert ("I've fumed furniture and it faded") to help us and our clients understand what happened.
Thanks in advance. I know this question does not directly relate to a woodworking project, but as fumed finishes do come up regularly, I hope the answers will serve the Woodweb community just as they will help us. (Also for what it's worth, I'm a professional house carpenter. I even own four tablesaws, two thickness planers and a powermatic 8" jointer. Good enough?)

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2/29/16       #2: Fumed oak fading in light. Any sour ...
Richard Member

Hi Doug, My thoughts on your problem with the "fumed" white oak floor is what you have there is not fumed oak. I'm long experienced in wood working and finishing white oaks and frequently fume my white oak furniture and framing projects. I have to tell you that your 8% NH3(aq) is far too weak. I commonly use 26% - 32% strong aqueous ammonia solutions. Further the fuming process is achieved by enclosing the wood project in a sealed atmosphere environment for some hours with a pan(s) of the strong NH3(aq). Depending on the species/quality of oak I will in addition occasionally dampen the wood with a weak tannin solution to achieve the darkest fumed colors in oak wood. Never applied aqueous ammonia directly to the wood. Advise you to google procedures for fuming white oak. Below is a link for one of my used sources for strong 26 degree NH3(aq). Link: Stronger NH3 solutions can be sourced through a Lab Chemicals suppliers. As to UV bleaching out the color of our wood wook, it is the norm. I nearly always advise the client about UV blocking glass and films for windows.

Link to Product

2/29/16       #3: Fumed oak fading in light. Any sour ...
Paul Snyder  Member



Lightfastness is relative. Some pigments are able to resist change extremely well when exposed to the energy from light – others fade relatively easily. Dyes all fade easily compared to lightfast pigments, but some dyes are more lightfast than others. Treating wood with ammonia is comparable to dyeing it – it will fade with exposure to light.

Richard is right in that you didn’t fume the oak since you applied the ammonia as a liquid. The end result is essentially the same though… the color of the wood is darker. Ammonia (in liquid or gaseous form) reacts with extractives in the wood called tannins. The reaction changes its atomic configuration a bit to form chromophores that look darker than the original color. Chromophores create colors by the way free electrons (delocalized electrons) are arranged.

The energy from light, especially ultra-violet (UV) light, knocks the electrons around which damages the chromophores and changes the color. Light has the effect of bleaching the color.

To protect items from sunlight, use UV blocking films on the windows, curtains or shades, and UV additives in the finish. These steps can drastically slow the rate of damage/bleaching.

2/29/16       #4: Fumed oak fading in light. Any sour ...
Bob "Boardman" Borders Member

I've done a fair amount of fuming to replicate the Stickley look. The points raised by Richard and Paul are correct.

First this isn't really fuming. Fuming requires an ammonium hydroxide solution in the range that Richard describes. You an get a 28% solution from surveyor supply shops, since this is what's used for blueprints (btw, household ammonia is about 5% - make sure you have good respirator equip when doing this). Richard's other point is the key. The ammonium hydroxide & wood have to be encased in an (or close to) air tight environment. You can wrap the wood (or enclose it) with 3 -5 mil thick plastic wrap. When wood is properly fumed, if you saw open a cross section you'll see a line of darker wood between 1/16 in. and 3/32 in. deep.

Typically pieces are fumed for 9 - 12 hours. You should let them sit at least overnight to off-gas any ammonia fumes/odor. When they first come out of the fuming they will look a bit gray - don't panic. Once you apply a coat of finish you'll see the real color.

As to Paul's point, sun bleaches color out (except on the skin of us Irish - then it adds a nice scarlet "Irish Tan" to our faces). So some type of UV protection is required - either on the wood, or in the area in which the wood will reside.

3/5/16       #6: Fumed oak fading in light. Any sour ...

About the closest thing I think you'll find on the web is a technical paper titled "UV Resistance of Ammonia Treated Wood". You can google it and download the whole paper. It concludes that fumed "oak" is relatively stable with exposure to UV. However it doesn't specify what type of oak and many other fumed species are not stable with exposure to UV.

Whether you wipe on household ammonia or fume with industrial grade ammonia you are chemically modifying extractives in the wood, or simple put; artificially aging the wood. The treatment method only varies the depth of penetration, not the chemical changes. Extractives can be either water or solvent soluble and vary tremendously between species and even within a single tree. Because different woods have different chemical compositions and different extractives they react differently to ammonia treatment and they react differently to UV exposure. If different oaks have different extractives, even within a single specie or tree, making a one size fits all statement (ie: "fumed oak is light fast") is rather misleading. It appears you have proved that to be true.

I would not overlook the floor finish. If it was tinted with a dye it could be the culprit.

3/5/16       #7: Fumed oak fading in light. Any sour ...
Paul Snyder  Member


Yes, UV does fade wood that has been fumed or treated with liquid ammonia.

Here's an excerpt from an article on the topic;

Title - Colour Changes of Modified Oak Wood in Indoor Environment
Authors - Josip Miklecic – Andreja Kasa – Vlatka Jirous-Rajkovic -
Publication - European Journal of Wood Products, 2012

“Heat treated and ammonia-treated oak wood showed rapid colour changes during the first days of exposure to UV light....

The absolute colour change of heat-treated and ammonium-treated wood increased during the time of irradiation and did not stop at the end of irradiation, while the absolute colour change in unmodified wood reached its maximum after 16 days of irradiation and then started to decrease....

The change in brightness (delta L) shows that the heat-treated and ammonium-treated wood were brightening, while unmodified wood was darkening during exposure to UV light.”

Conclusion - Ammonia reacts with the tannins in the wood to produce darker colors. The radiation energy from the sunlight fades the color.

3/5/16       #8: Fumed oak fading in light. Any sour ...
Doug Horgan  Member


Thanks for the help! Those papers are exactly what I was hoping to find.
I'm very impressed with your researching abilities! If you have a minute, can you help me understand how you guys were able to find those publications?

5/2/16       #9: Fumed oak fading in light. Any sour ...
Dustin Member


It's not that the fume colored, it's that the sun faded the color on the other wood. This is very common with use of oil based products and lots of exposure to the sun. I assume this is Rubio Fume, if so maybe ask Johannes Boonstra he's the Midwest Rep and he can confirm this. You can find him on Facebook. Any other questions, I'm available too as I know quite a bit about this stuff. Best of luck.

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