I'm starting to experiment with fuming qtr sawn white oak. The
articles say you need the commercial 25% ammonia but I've also heard
that household ammonia will also work.
What I'd like to know if ammonia concentrations simply affect the time
to achieve the required result or if the concentration affects color
(ie will 5% ammonia achive the same color result as 25% ammonia but
just take 5X the time??)
On a bit of a tangent, the diazo prints (think blueprints) that were
the standard fare in construction for ages, were made with a high
strength ammonia process. You used to be able to buy spent solution
from them for next to nothing, or they'd give it to you for free. Now
that they've pretty much all switched over to computer
printing/plotting, and I'm no longer cranking out drawings, I don't
know if a blueprinting shop stills has ammonia based processes. I kind
of hope not - that was some nasty stuff.
Stronger is faster - how much, I can't say.
Nice console table, Doug.
It depends upon the ambient temperature. The warmer it is, the faster
the results. I've done some experiments with both and the household
and blueline strength were at the same darkeness (dark caramel brown)
after 24 hours. The household never darkened beyond that but the
blueline took it all the way to black. Here's a webpage
http://musial.ws/ammonia_experiment.htm but I never got around to
updating it. Basic result - the blueline pulls ahead early, the
household pulls even after about 24 hours then the blueline hits 4th
gear and never looks back.
Long story shot, household ammonia gives a very good color after 24
hours. (For more fumes, put the ammonia in a pie pan and light a
votive-sized candle under it)
I did some white oak fuming over the summer and can offer some
observations. I had the same 5% vs. 25% question. I happened to have
some "Janitor" strength ammonia laying around ( not sure of the percent
but it was clearly stonger than household ) I decided to try this first
before going through the hassle of chasing down 25%. The color I was
after was a deep dark brown. I made a tent for the piece and also threw
in some test pieces. I let the piece fume for two days before testing.
Putting some BLO on it revealed a markedly darker color but still
lighter than what I wanted. I sealed everything back up and checked the
next day. I didn't observe any changes. After checking on it two days
later it was still the same color as the first test.
Since I wanted a much darker color I got some 25% ( had to mail order
it ) and put it in the fuming tent. After eight hours there was a
distinct change in color. I wanted it even darker and let it sit
overnight. The next day it was much darker ( so much that I thought I
fumed too much but after oiling and shellacking the piece it was just
right ) Based on my observations I would definitely say that the depth
of the color attainable is directly proportionate to the %.
Some general observations on fuming.
If you need the strong stuff observe every safety precaution. Every
danger you've heard about 25% is true. This is really nasty stuff. Full
ammonia-rated respirator, thick gloves and tight fitting goggles. I've
seen pictures of peoples using fans to direct the vapors away and I
personally think that's nuts. I got one stray waft of fumes wearing
some vented lab goggles and immediately went out and bought a pair of
Speedo type goggles, the kind that seal all the way around. I was
extremely impressed by the caustice nature of this stuff. I also
noticed that ammonia is very light bodied and easy to spill. Use heavy
glass dishes for the trays. I used disposable plastic bowls and managed
to spill a little bit.
I fumed two pieces. One was flat sawn and the other quarter/rift sawn.
The QS piece had a much more consistent color than the FS piece. I'm
not sure if it was the quality of the FS wood but in the future I will
probably only fume QS. I hate staining in general and, going forward,
this is probably the only way I will color wood . Once you get set up
to do this, it's really quite easy and much less hassle than staining.
Having a color that you can't easily sand through is a pleasure. I also
discovered that the advice about using wood from the same board or tree
for the whole piece is valid. The QS piece is a box spindle chair and I
ran a little short on the 8/4 board I was using and used some
additional wood on the back. The color difference is quite noticable
but fortunately in an inconspicous place.
Last observation. When you're actually fuming the wood it will turn an
unattractive dingy sort-of-grey color. This is normal. You need to put
a finish on to express the real color. Although I wouldn't swear to it,
it seemed like my test samples, after applying BLO, darkened somewhat
Anyway, good luck with the experiment.
You don't have enough information to justify that conclusion -- you didn't run
a parallel test in which you added more of the original solution to see how
that compared to adding more of a stronger solution. The only conclusion that
can be justified on the basis of the experiment you describe is that adding
more ammonia increases the depth of color.
Doug Miller (alphageek at milmac dot com)
I did a sample trial using a scrap of oak, plastic bucket, and
household ammonia. It really turned out good however I noticed that it
magnifies the contrast between sapwood and heartwood.
For my table I've minimized sapwood and tried to match color and grain
patterns as close as I could. However there are some areas of color
inconsistency in the raw wood.
Is there a way to adjust the fuming technique to get a little more
darkness in the lighter colored wood so it evens out in the end? I
heard something about using tea to force a little more tanin into the
wood so it darkens more.
Does this imply I can rub a tea bad on the sapwood to get a little more
darkness out of the fuming process??
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.