Unexpected amonia fuming results -feedback requested

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scsmith42

New User
Scott Smith
Many of you will recall the post I put up last month seeking advice regarding amonia fuming: http://www.ncwoodworker.net/forums/f29/looking-advice-about-amonia-fuming-25033-post252634/

Earlier this week the big slabs went into a plastic tent structure, and 16 oz of what was supposed to be 28% amonia was poured in via a tube into a plastic container inside the tent (thanks Alan for the great idea).

I wore a respirator when I poured in the amonia, but could still sniff enough to know that it smelled like amonia!

Earlier today I peeked into the tent (at least the part that I could see through the plastic), and not much coloration appears to have taken place. Granted, my desired end result is sterilization, but it seems to me that the coloration would be an indicator of progress. There still appears to be 1/2" of amonia in the bowl too.

Additionally, from a small hole in the plastic (that had been taped up), I could not smell any amonia fumes whatsoever when I untaped it earlier today.

Does anybody know if this normal, or did I get a bad batch of amonia?

Thanks.

Scott
 

Ozzie-x

New User
Randy
Scott,
I'll defer to some of the chemists on the site as to the concentration, bad batch,etc. It should be a simple volume thing. I will say that I have been under-impressed with some of my ammonia adventures. I believe some of the worries amy have been blown out of proportion and have lead us to expect something more than what it is. The trick may be to get the ammonia to come out of solution from the liquid. I've tried putting fans in the enclosure blowing over the liquid that seemed to help some, but the sheet plastic enclosure also makes a great greenhouse that will bring about some radical results (bad for furniture, DAMHIKT) when placed in the sun.The greenhouse effect really gets things rolling but also produces lots of water, dripping, and will mess up your project. Could sit the ammonia on a hot plate? Since your application is more of a utilitarian nature, it may not matter. If the ammonia doesn't work, you may try tobacco bed gas, but be careful if you do- it's one of the most poisonous chemicals I know.
 

timf67

New User
Tim
Scott,

Your results will depend on the concentration of ammonia vapor, which in turn depends on the air volume of your tent, how well sealed it is, and how much ammonia is evaporating. If your tent is as small as possible and well sealed, the next step would be to increase the surface area of the ammonia and the temperature inside the tent. Evaporation is an equilibrium, so you want to maximize the surface area of the liquid (think plastic oil change pan) and keep the temperature elevated. Make sure your tent is in sunlight during the day, you want it to be at least 80+ degrees inside.

As for a bad batch, I won't say it is not possible but it is not likely unless the container it came in wasn't well sealed. We get our ammonia in IBC's and we did have a situation where one of the IBC's was not sealed and the concentration of ammonia had dropped. But for your application, there should still be plenty of ammonia available for fuming. Feel free to give me a call if you want to discuss it, I think you still have my cell number

Tim
 

scsmith42

New User
Scott Smith
Guys, thanks for the feedback.

Tim, the tent is in the sunlight, and is only a little bit larger than the material stacked inside. Offhand, I'd guess that it's footprint is 5 x 7, and around 4' tall. The ammonia bottle was very well sealed with tape around the cap.

The ammonia is in a plastic tray about 10" wide and 14" long, placed on the bottom of the tent.

The thing that surprised me today was not being able to smell any ammonia fumes. I took the plug out of the end of the 5/8" rubber hose that feeds the tray, and slapped on the tent sides a few times to try and force some fumes out of the hose, but never smelled anything other than the rubber hose smell.

By the same token, in one spot of the plastic there was a tear which we taped up, and I removed the tape and carefully sniffed, but did not detect the ammonia vapors. Seems a little odd to me, as I could really smell them when I poured the liquid into the tray.

Although I'm not after coloration, I would presume that the color change would be a good means to discern how much ammonia has penetrated the wood. From what I can see, nothing has changed color (or if it has, it's not very dark).

The tray does look pretty full from the outside - does not look like much evaporation has occured. There is definitely a lot of condensation inside the tent!

Hmm, I can definitely put in a much larger tray, I'm wondering if putting a heating pad underneath the existing tray would help to evaporate the ammonia? I'm also wondering if the air inside the tent is too saturated with water (since the slabs were green), and that this is preventing it from allowing much more ammonia evaporation?

Randy - on another topic - I've been meaning to tell you how much I admire the dovetails and drawers in your avatar photo. That really looks like some outstanding craftsmanship and artistry! Do you have any larger photo's of them?
 

Ozzie-x

New User
Randy
Scott, Sounds like you at least have an evaporation problem.Can't say if the environment inside your chamber has gotten vile enough to kill off any bugs?? Thanks for the compliments on the dovetails, they did turn out well and actually went pretty fast. They probaably turned out good because I didn't fettle with them much, I was just trying to get them done. I have uploaded some more pics into my photo gallery and will attempt to attach the larger picture to this post.
DSCF0025x.JPG

View image in gallery
 

timf67

New User
Tim
Scott,

My only guess is that the ammonia evaporated and escaped your tent. The ammonia will evaporate quickly if the tent is in sunlight and if the tent has any holes it will escape. Don't be fooled by the appearance of a lot of liquid in the tray, 28% ammonia (by weight) in still about 85% water by volume and the humidity in the tent will keep the water from evaporating - but the ammonia will still evaporate. I also forgot to ask what material your tent is made out of? Be sure it is a thick polyethylene sheet like you would use for a moisture barrier in a crawl space. I would go ahead and dump out the "ammonia" in the tent since it may be mostly water by now and recharge with some fresh ammonia if you have any left.

Tim
 

scsmith42

New User
Scott Smith
Randy - that piece really looks outstanding. Thanks for uploading the new pix; I'm headed to your gallery as soon as I post this.

Tim - thanks for the info - that makes sense. I have 16 oz of 28% AH leftover, so I'll dump what's left in the tent and give the new stuff a try.

The first go-round, I poured all 16 oz into the tray. This time I may opt to pour 4 oz at a time.

The outer skin of the tin is a heavy clear poly material.
 

Jeff

New User
Jeff
Scott, I agree with Tim and Ozzie, but here's another thought.

The volume of your tent is about 140 cubic feet and the density of ammonia vapor relative to air is 0.589 so it's much lighter. My suspicion is that your ammonia gas is concentrated at the TOP of the tent so the entire atmosphere within that 140 cubic feet is not really saturated with ammonia vapor. That might explain why you don't smell anything and also why the wood is not showing any color changes as expected (it's still in air, below the ammonia cloud).

Also, 16 oz. of 28% ammonium hydroxide is only about 125 grams of ammonia gas (diluted by 140 cubic feet of air). The upshot is that the concentration may be too low to effectively do the fuming process.

You might try circulating the air and kick it in the arse with another good shot of ammonia. :dontknow:
 

Mike Davis

Mike
Corporate Member
If all you want to do is kill anything in the wood you can do that.

PM me or your probably already know.

It is extremely dangerous so I won't post anything here and ask that others please do not.
 

scsmith42

New User
Scott Smith
All - thanks for the additional feedback (and Jeff - thanks for the calculations - I now have a much better understanding of how this process works).

I've just ordered 4 litre's of 50% AH. While I wait for it to arrive, I'll use up the remainder of my 28% solution. I'll also double check the upper portions of the tent for any potential leaks, and also significantly increase the size of my plastic trays when I add the 50% solution.

One thing that concerns me is that the slab most in need of fuming, is located at the bottom of the stack and only 5" or so above grade. If it's going to be exposed to some strong AH fumes, I either need to really saturate the chamber or rethink my approach. That darn slab weighs almost 900 lbs, which limits my ability to move it to the top of the stack (stability concerns).

One question - are the AH fumes explosive? The reason that I ask is that I'm wondering if some type of recirculating fan would help provide for more consistent exposure to the fumes. Something like a low voltage muffin fan could be utilized. However I don't want to use this approach if there is any danger of something going "bang"....

Scott
 

Jeff

New User
Jeff
All - thanks for the additional feedback (and Jeff - thanks for the calculations - I now have a much better understanding of how this process works).

I've just ordered 4 litre's of 50% AH. While I wait for it to arrive, I'll use up the remainder of my 28% solution. I'll also double check the upper portions of the tent for any potential leaks, and also significantly increase the size of my plastic trays when I add the 50% solution.

One thing that concerns me is that the slab most in need of fuming, is located at the bottom of the stack and only 5" or so above grade. If it's going to be exposed to some strong AH fumes, I either need to really saturate the chamber or rethink my approach. That darn slab weighs almost 900 lbs, which limits my ability to move it to the top of the stack (stability concerns).

One question - are the AH fumes explosive? The reason that I ask is that I'm wondering if some type of recirculating fan would help provide for more consistent exposure to the fumes. Something like a low voltage muffin fan could be utilized. However I don't want to use this approach if there is any danger of something going "bang"....

Scott

Ammonia is not generally explosive so a low voltage muffin fan within the tent should be okay. However, I'd prefer that some of our chemical engineers address that question .

Another option is to buy a cylinder of ammonia gas (Fisher wants $311 for a disposable lecture bottle containing 8.46 cubic feet), but that price will drop with volume, but at what price? If your tent leaks in the least bit then you're just giving Mother Nature a free ride for fertilizer. She can make it a heckuva lot cheaper.

My friend, we may have bitten off more than we can chew for this project just to sterilize the wood! Someone mentioned tobacco field sterilant which is usually methyl bromide---need a license to use and administer and it's a known potent carcinogen so even more stringent safety/protection will be required.

I can direct you to a steel mill in Ohio that can sterilize that joker in just a few seconds, but I don't think you'll have much left over. :evil:
 

CarvedTones

Board of Directors, Vice President
Andy
You're not far from Harris, right? ... Oh, wait, scratch that idea; might end up with 3 headed 40' long wood worms! :rotflm:
 

Warren

Warren
Corporate Member
Just a quick thought. I assume that you have all six sides of the enclosure covered with the plastic sheeting? Especially the bottom. Could that be some of the loss? Seems Mother earth could be a good amnonia sponge.
Warren
 

scsmith42

New User
Scott Smith
I assume that you have all six sides of the enclosure covered with the plastic sheeting?
Warren


Warren, that would be a logical assumption...

There are probably some small cuts / holes in the plastic sheathing that I haven't found. I'm hesitant to sniff too strongly around it with the ammonia inside...

Hmm... that gives me an idea - I have a freon / lpg leak sniffer. I'll try it near the ammonia bottle to see if it alarms. If so, I can use it to find any small leaks in the tent.

We'll see how the 50% solution works - should be here by the end of the weak.
 
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