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Fuming a Small Box With Household Ammonia #3: Fuming the Box Interior

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Blog entry by Roger Kimmel posted 09-21-2014 10:22 PM 1729 reads 1 time favorited 4 comments Add to Favorites Watch
« Part 2: After Six Days of Exposure Part 3 of Fuming a Small Box With Household Ammonia series Part 4: Fuming Through the Finish »

Two days after I took it out of the “gas chamber” the swelling due to moisture had gone down enough that I could remove the lid. I was a little surprised that the interior had darkened as much as the outside, but I guess I shouldn’t have been. The lid was certainly not airtight. What did surprise me was that I had put a coat of Danish oil on the inside prior to assembly, and the ammonia had darkened the wood right through this small amount of finish. It just shows how permeable a finish like this is, and how something like ammonia or water vapor can penetrate it. I may try an experiment with a film-forming finish like polyurethane to see it the ammonia can penetrate that.

About the box taking up moisture – I tried another experiment. I placed another small box in the gas chamber, this time with some water instead of ammonia. The box did pick up some moisture, but not nearly as much as the box with ammonia. This seems to suggest that the ammonia somehow makes the box take on moisture. On the other hand, the nights have been a bit warmer. Maybe there was just less condensation this time around because of the temps.

The chemistry of wood fuming is not well understood. A nice research article is here. This work showed that of the species tested, oak, maple, spruce and larch; all darkened, but oak darkened most quickly and intensely. The research suggested that the tannin in the oak was responsible for the darkening, but different compounds in the other species were responsible for darkening them.



4 comments so far

View Dark_Lightning's profile

Dark_Lightning

2635 posts in 2577 days


#1 posted 09-22-2014 12:59 AM

Nice box, and interesting article. Darkening oak with ammonia is something I have done before, but with red oak (and patinating copper). Not as spectacular results, but good enough for that project. Since white oak reacts so quickly, ammonia fuming seems like an economical process. But having to wait 16 days for the other species would indicate that a different method should be employed for them

-- Random Orbital Nailer

View Roger Kimmel's profile

Roger Kimmel

36 posts in 847 days


#2 posted 09-22-2014 01:16 AM

Thanks Dark Lightning. Yes, if you want to fume other species, you better not be in a hurry. And remember to add in 16 days for a test piece before you do the real thing. I bet the results probably vary from tree-to-tree within a species too.

View robscastle's profile

robscastle

3393 posts in 1672 days


#3 posted 09-22-2014 03:00 AM

Humm… Dark Lightning eh? I guess its a strike that has gone through an Ammonia cloud?

Roger,

Years ago I used to work in a place where there was an Ammonia Printer I had to use.
It didnt half pong I tell you and the smell was so bad nobody else in the place would use the machine, It was so strong the fumes rusted out the extraction ducting !!

Anyway enough of the frovolity, I wanted to conmmend you on your work, it looks really nice, tempting me to revisit my ammonia experiences and give it a go.

-- Regards Robert

View Roger Kimmel's profile

Roger Kimmel

36 posts in 847 days


#4 posted 09-22-2014 11:19 PM

Thanks Robert. The household ammonia is not so noxious, and the results are nice if you are not in a hurry. The moisture on the wood is a little bit of a problem, but I bet if you set up in a warm place, this would be mitigated.

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