Aqua Fortis turned Maple green?

[necchi]

I just used some aqua fortis,(original Wakon Bay), on a small piece of curly maple for a neck knife handle. It's not bad, but a few areas have a slight greenish hue.
I applied just a light dampening coat as typical, then toasted over an electric range, gave it a baking soda wash.
Is it just a odd piece of maple or could the age of this previously opened bottle have something to do with it. I bought 5 bottles at a shop close out 7 years ago. Could the water have evap'ed a bit and left the nitric too strong? There is no sign of sedement or crystlization in or on the bottle??

 

[bioprof]

I think that the greenish hues happen if the wood isn't heated enough. Try heating it some more and see if the green color disappears. If not, you can always change the tint with an alcohol stain. AF works well with alcohol stains.

 

[pichou]

AF tends to the green side of brown anyway. A watered down alcohol cherry stain will take the greenish look away.

 

[paulvallandigham]

To avoid the green, you have to really heat the stock, and then wash it down with baking soda and water to remove all the acid. Several washings are a safe bet. AF is designed so that the nitric acid( and iron) is used, with heat, to darken the wood. But, you have to remove the acid, or it continues to act with the wood and moisture in it. That is what causes the stocks to turn green over time, even under a stock finish!

 

[longrifle78]

If your gettin green with aqua fortis your not heatin it long enough, keep applyin heat until all green is gone and the wood is a good brown color. And AF will not turn green over time, it will turn a darker brown if anything.

 

[paulvallandigham]

That may be your experience, but one of the first guns made by another club member here turned green because he " forgot" to wash the stock off with water and a thick baking soda paste after he heated the stock to get it brown. It was brown. But, a year later, it was noticeably GREEN. He had to strip off the stock finish, Then wash the stock several times with baking soda, then dry the stock, then touch it up with AF again, then heat it again to get it the color he wanted, AND THEN, wash the stock with another paste of baking soda, leaving it on the wood long enough that bubbles stopped coming up through the water/paste. Finally, he was able to refinish the stock.

He laughed about it. It was his first gun, and he actually signed up at another local community college to learn how to build replica MLers when he built the gun. He considered a great lesson that he learned, and went on to build another gun for himself, and, later, a gun for his son. He was always telling new members to the club to " NOT forget to wash that stock down 'good' with baking soda and water" and then would tell them what happened to his first stock when he didn't.

 

[wildeagle]

I've always heard that when using AF to use heat and neutralize after. Now I've not used AF, or built a 100 guns, so I'm not an expert on the matter. I did however build a Lancaster .50 cal., and stained the stock with a very strong solution of coffee, yes coffee, not instant but brewed, and very strong, black coffee. The stock came out a very nice dk brown,and finished with a few thin coats of tru oil. Now, 15 yrs later the stock has a very subtle green color to the stock, not offensive, but not that warm brown color that most people like. I didn't rinse the stock after applying the coffee, just applied the tru oil. I am wondering if the acids in the coffee could have something to do with the color change? or maybe a bacterial thing going on or maybe UV effects ? I'm hoping some of the more accomplished builders will chime in, thanks. Oh and by the way, it was'nt decaf it was leaded. :haha: :haha:

 

[jbtusa]

Be careful when heating the knife scales to darken the aquafortis. When I did my knife handles with heat, the wood warped and created gaps between the blade tang and the wood handles.

 

[paulvallandigham]

The acid in coffee reacts the same way the nitric acid in AF does to Maple. If you didn't wash the stock with a Baking Soda/water mix, letting the baking soda sit on the wood long enough to get to all the acid in the wood, that is why your stock is turning green, now. Strip the finish, wash the stock with the mix, and then refinish. Its not anything in the acid that produces the green color. Its the sugars in the wood that do. I have seen this occur also on very old Walnut and Oak furniture, where the wood was stained but not washed to neutralize the acids. Years later, there are subtle green streaks in the table. I have an oak claw foot table my grandparents bought back in 1905. The leaves to extend the length of the table stayed in a rack in the attic of their home for years, when the table was moved into the kitchen, and left "round" to fit the available space. When I acquired the table in 1978, and we got all the dust, dirt, and crud out of the wood finish, a couple of the leaves had streaks of green in them.

Dad happened to use Baking soda/water to clean the wood Before he applied new Walnut stain to the wood, and the Green disappeared. The stain he used was an alcohol-based stain, and he didn't have to heat it, or wash the wood again after staining with it. That is as good an " Experience" story I can give you. :hatsoff:

 

[Bob Gular]

I have been using Aquafortis for years on stocks, furniture and knife handles. After the application of heat and the green is all gone I just wipe the wood down with distilled water(from the dehumidifier)and let it dry. Schmutzing it up with baking soda paste is a myth started by the Arm&Hammer Co to increase sales to the gullible. Also,the story about the rifle turning green is a lot like my wife's homemade biscuits, really hard to swallow.

 

[Stophel]

To stain maple with AF: With the surface prepared, slop the AF on heavily. Let it dry. At least an hour with sugar maple, at least a half hour with red maple (silver maple is only good for firewood. My opinion is about the same for a lot of "red" maple), or just however long it takes for it to get really dry. Sugar maple will generally turn a grayish color, red maple will generally turn a greenish color. When it is fully dry, heat the wood to turn the color. I use a heat gun, but something like a hot plate is actually better (radiant heat works better than hot air), if you have one. Now, there still might be some areas that are not fully turned color. That's fine. I take a glass slide and go lightly over the wood to take care of any "whiskers" and then stain again. You need at least two applications to do it. You can stain it over and over. Once it reaches a certain color, it will not get any darker, no matter how much you put on it (it will reach the point, however, where it will be hard to get any more to soak into the wood). Once you are satisfied with everything, then neutralize with a lye solution (Red Devil lye...or, you can do like they did 200 years ago, and leach it out of wood ashes). Be careful, of course, since lye will eat your fingerprints off. The lye solution will turn the color more reddish. When done with the lye, wash the wood off with water. Let it dry for a good long while (a day or so), and it's ready to finish.

I have found that AF tends to turn sugar maple more orange and lighter color, and red maple or other lesser maples darker and more brown.

 

[wildeagle]

Thanks fellas, some good thoughts to ponder. The gun doesn't look god awful or such, but it doesn't have that rich traditional look either. It might be a good project for the summer, I'll take some before and after pics so you can see the color difference.
Bob, a good friend, Bill, has been building guns for living since the early 70's and he ran into this problem early in his career. Some of his first guns were so green you could lose them in the woods. If you leaned it against a tree and walked 10 feet away it blended right into the foliage. On the up side it would make a good camo for a turkey gun. Oh, try a little buttermilk with those biscuits, makes them a little more palatable :haha: :haha:

 

[rabjr]

Thats caused by a different stain, not AF.

 

[Stophel]

Chromium Trioxide.

Apparently, this actually was used as a stock stain, at least in the late 19th century. I remember years ago, I went to see the gun collection of a friend of my dad's and he had an 1860-70-80-ish fullstock percussion rifle, small caliber, with a long brass tube scope on it. The stock was as green as a pea.

Aqua fortis starts green, then turns brown. Chromium Trioxide starts brown, then turns green...

Every one of my maple stocked guns HERE is stained with Aqua Fortis (most of it made by myself). No green left. Now, on one or two of my earlier guns, I did have a problem with a slight remaining green cast, but on those, I just stained once and that was it.

 

[necchi]

Ty guy's. I've used AF before on some knife scabs and a few kit gun's with good results, but this is the 1st time I saw green. Thank's to the explanations, I now know that I just hurried the heating part of the job, and I didn't let it dry before applying the heat. I guess that little neck knife handle was just too short to hold next too the stove,(ouch!)
I learn a lesson about needing the neutilizing or baking soda wash. It was a tradition trapper pistol kit from deer creek,,I never gave it a wash, just rinsed with tap water. That stock just kept getting darker and darker,,it got so dark, all the hylight of the grain (the origonal intention) was really kinda lost.

 

[wildeagle]

Chris, fellow members, I stand humbly corrected. :bow: I just talked to Bill, and he said that it wasn't AF. But that chromium trioxide was the culprit. I do remember that the gun he made was as beautiful light green as the ferns next to it. My .50 cal is not the same green. It is a light brown with a light olive hue to it. If not for the smooth rifle I'm in the middle of I would give it a go post haste, but I'm not that great at multi tasking. It will have to wait till I'm done with the project at hand. Again , sorry for muddying the water. :redface:

 

[Tumblernotch]

Chromium Trioxide.

Apparently, this actually was used as a stock stain, at least in the late 19th century. I remember years ago, I went to see the gun collection of a friend of my dad's and he had an 1860-70-80-ish fullstock percussion rifle, small caliber, with a long brass tube scope on it. The stock was as green as a pea.

Aqua fortis starts green, then turns brown. Chromium Trioxide starts brown, then turns green...

Every one of my maple stocked guns HERE is stained with Aqua Fortis (most of it made by myself). No green left. Now, on one or two of my earlier guns, I did have a problem with a slight remaining green cast, but on those, I just stained once and that was it.

I was trying to remember the name of that stain! I knew that it had chromium in it. That will definitely turn a stock green. I bought a used John Hall longrifle once that was green as a gourd. Had to refinish it. I also remember seeing a Hawken hanging in our local shop years ago that was a beautiful reddish brown on one side and green on the other. The side that turned green had been exposed to sunlight over a long period of time. I'm wondering if sunlight accelerates any chemical changes in chromium trioxide?

I use Wahkon Bay AF on my stocks and have never had one turn green. Like you said, it's kinda green when you first start heating it, but turns into a very rich reddish brown. I kill it with boiled linseed oil. Other than wear marks from repeated handling, it just gets darker over the years.

I also use Wahkon Bay Browning Reagent for browning barrels and hardware. Be hard to find a better solution in my opinion for either job.

 

[Bob Gular]

Gues you gotta neutralize that stuff with buttermilk.

 

[wildeagle]

:bow: Yeah,I guess it would make that coffee not so stiff. :redface: