Nelsonite Problem

C

Chris Meyer

Joined
Aug 15, 2005
Messages
1,297
Greetings everyone,

I modified one of Harbor Freight Tool's 2.5 gallon paint pots (which are on sale, by the way) to make a vacuum chamber for "stabilizing" wood in Nelsonite. It works pretty well, except that the Nelsonite is brutal on seals. The paint pot came with a rubber seal, which after a short time began to disintegrate. I have tried a variety of materials to replace the original seal, but none have been able to stand up to the fumes for more than a few days. Is there any readily available gasket material that will resist the Nelsonite? Apparently, there is a lot of Naphtha in it.

As an aside, has anyone tried the Resolute product that Cue Components markets as an alternative to Nelsonite? They claim that it works just as well, but is a lot less dangerous.

And yes, I know that I can send wood to WSSI or K&G to have it really stabilized. In fact, I have some wood out to WSSI now. However, the Nelsonite seems to work pretty well, and it's cheaper and more convenient than sending all of my wood out.
 
I dunno what the top of the paint pot looks like, but you can try 3M 5200 and make a custom fitting seal. Use the thickest axle grease you can find on the pot rim so the 5200 will stay in the lid, or vice versa depending on wherever the recess is for the O ring. If you are afraid of the permanency of the 5200 try plain jane caulk and grease whatever you do not want the caulk to stick to. It is easier to remove if you do not get it right/too much excess the first time. I use cosmoline cause I have a whole bunch laying around for my long term rifle storage. On the flip side after the caulk has dried if you have a problem getting a good seal, try a thin coat of same axle grease and see if that helps get a seal.

If you only use the pot once in a while, try greasing both sides, lay a bead of caulk and seal the pot up wet caulk and all and pull a vacuum. The stuff dries and you have to clean out the dried caulk but if you only do that every now and again it's not that big of a deal.

If that's too much of a mess then you might want to try finding a tygon O ring. I think that stuff does not get eaten up like natural rubber.
 
So far I've tried the original rubber seal, lithium grease, rubber weather striping, permatex, and plumbers putty. None of those held out for long.

I did a quick check of the web and found tygon tubing, but not round gaskets. Perhaps just stuffing the tubing into the gasket recess would work?
 
Tygon's a bad choice around naphtha. It'll fall apart quicker than rubber, even.

Is this an o-ring or flat gasket?

Decent nitrile rubber may work (though I doubt it), but Viton A would be better for an o-ring. Sadly, it would probably cost as much as your paint pot, Chris. The chemicals in your Nelsonite called "aromatics" are notrious for swelling and ruining gaskets. You need what is called a "fluoroelastomer".

I am surprised, though, at your problem. I have the HF paint pot that preceded the newest model and have run the Nelsonite in there under pressure for days without a gasket issue. They must have changed formulations. Welcome to the Chinese product age. You might go to your local NAPA and ask for a snippet of their rubber gasket sheet and see how badly it swells when exposed to Nelsonite. Probably horrible. They all swell, but as long as it doesn't blow out or crack you're ok.

The other choice at NAPA would be compressed cork. It's a surprisingly good gasket.
 
Darn I thought Tygon was the answer. Well, then again too, switching to Winwax hardener and Acryloid B72 could be an option too, it has MEK in it instead of naptha...:D
 
Fitzo, I will try the cork, as it is readily available.

As for the tygon tubing, I saw on the US Plastics website that they sell something called Tygon® Ultra Chemical Resistant Tubing. It shows a picture of some that they subjected to MEK for 16hrs, with no apparent damage. Since you're the Chemist, are MEK and Naphtha anywhere near comparable?

You also mentioned fluoroelastomers (which I don't know anything about), and I see that US Plastics also sell Fluran® F-5500-A, which they describe as "a proprietary fluoroelastomer" that "...has excellent resistance to corrosive chemicals, oils, fuels, solvents and most mineral acids." If you think that would work, I'll try to get some as a more long term solution.

P.S. I just found a place that sells the Fluran tubing by the foot, so it shouldn't be too expensive for the small amount I'd need.
 
Chris Meyer said:
.....since you're the Chemist, are MEK and Naphtha anywhere near comparable?.....
Click to expand...

No, MEK and naphtha are two different classes of chemicals, though both are sorta rough on alot of plastics. You can think of naphtha as a petroleum cut...diesel, kerosene, gasoline, naphtha...yadda yadda. It's always been famous for having benzene in it sometimes... :eek: Benzene's nasty. Hopefully they keep it out nowadays. What I smell a lot of when I smell Nelsonite is a lot of toluene and xylene... Not as nasty, but they sure do screw with rubber.

That grade Tygon is new to me. Regular laboratory grade Tygon wasn't used for much besides water. That stuff holds up to gasoline, supposedly, so it will tolerate the naphtha most likely. The one thing I would suggest is to maybe ask how stiff it is. We just usually went ahead and used Teflon tubing. teflon, however, needs a lot of sealing pressure to make it cold flow into shape. You might ask 'em if it's as stiff as polyethylene or teflon tubing, and if they say yes, I'd pass. You might also want to ask if it's heat weldable...not all tubing will melt together well to make yourself a ring.

Fluran, now that's nice stuff. We had solvent resistant 1/4" x 6" o-rings in both Fluran and Kalrez. They worked very nice. Kalrez cost us about $400 a pair.

Even the best o-rings swell in the presence of hydocarbons like naphtha or hexane. We had to have several sets and change them out between uses and give them a trip through a vaccuum oven to dry them out to shrink them.

Do you think it is just the vapors that are attacking your gasket or is it possible that there is enough nelsonite in your tank that when it foams initially (flashing off heat under vaccuum as it boils) that it is reaching up and wetting the gasket? You don't want liquid solvent bathing it. The best thing to do is have a vent in between the pump and the bucket. Start partially open and close gradually over ten minutes or so. That helps that.

BTW, if you smell fumes coming through your vac pump it's best to do good ventilation. Not knowing the solvent mix in the naphtha, it's best not to breathe that crap. Some naphthas contain carcinogens.
 
bladsmth said:
Not to mention what the solvents do to the seals in a vacuum pump.
Stacy
Click to expand...

Yeah, good point, Stacy. We considered pump seals preventive maintenance items. We had two PM guys in the building who did nothing but rebuild pumps. Once a year they'd come grab your pump and replace it with a rebuild.

We did a lot of very nasty distillations and even the best traps were never enough. it's amazing how nasty a pump can get inside and still pull 29+" vacs.

Nowadays I have a cheapass little diaphragm pump for biology stuff I bought out of scientific salvage at work. Pulls 27" on a good day on that paint pot so not bad for $25.
 
you could but in an intermediate chamber. Basically put another empty chamber in line with your vacuum pump. This helps to collect some of the nasty stuff that foams and evaporates. I have found that the old mason jars with a canning lid work great. I have a food saver lid sealer and I adapted it to one of the HF air vacuums. No moving parts and it pulls a great vacuum. I have used the nelsonite and the smell really gets to you. It will go away after a while (couple of weeks). I found another product that has a lot less naptha in it and will report on it once I try it.

Chuck
 
tell me the size of the pot gasket and I maybe able to built you one from durabla. It is a material we use for gaskets in the oil refining business. Have access to the gasket cutter. I doubt that your chemicals will affect it. Will trade for a interesting set of scales
 
Thanks guys, of course between potentially fuming myself or ruining my vacuum pump, I'm wondering if it's really worth it.

Fitzo, I just place an open 1 gallon stainless steel container inside the paint pot. I noticed tonight that the inside of the pot's lid was wet with Nelsonite. I'm not sure how it got there, since the stainless container is only about 1/3 full at the moment. Now I'm not sure it the seals are actually wet or not. I found that I can get enough of that Fluran tubing for about $25, which seems reasonable if it works.

I have a pair of filters with glass reservoirs on my vacuum pump. Is that good enough, or does that just trap actual moisture? I suppose it doesn't really matter if the pump fails. I've had it for about 20 years, and this contraption is the only thing I've actually used it for. It came with a vacuum frame that I once bought for silk screening.

ib2v4u, I'll have to measure the lid more exactly, but I believe it is about 10.5 inches across (probably metric though). I don't know if you have a gasket cutter that large, or whether I have any scales that you'd want, but let me know.

Thanks again guys.
 
Chris, what those traps will catch is the liquid if it foams out from too fast a vacuum. They would probably have to be chilled to actually condense the vapor.

The liquid on the inside lid is either from some reflux condensation or foaming.

I do the same thing with a 1gal can in the main pot.

Hope you can get your problems solved. If you want to see how I valved mine with a vent I can shoot you a foto.
 
I could cut a gasket 4 foot across if I needed to. We get the stuff in huge rolls. the cutter is really a simple device. I just need the id and od preferably in inches. You could trim the od some with your belt grinder if you wear a respirator. The id could be slimmed up with a drum on a drill press. This stuff is a bit like the stiff cardboard behind a pad of paper. Let me know. As far as a set of scales, anything interesting can go into the pile to wait for a blade that seems to want them.
 
ib2v4u said:
I could cut a gasket 4 foot across if I needed to.
Click to expand...

ib2v4u, Wow, that must be some machine! I just measured the lid, and it looks like a gasket with a 9.875" ID and a 10.25" OD would be about right. If you'd be willing to make me one, I be glad to try it. I'd be happy to send you some Nelsonite treated scales in return. I mostly have book matched Bocote and curly (?) Maple at the moment, so I hope you like those. I'll send you an email with my address and you can send me yours. Thanks again. -Chris

By the way, when I took the lid off I checked the gasket I am currently using. It's just some rubber weather stripping. The center of the lid was damp again, but the gasket itself appeared dry. I put it in two days ago, and it already had a section rotted away. I had to replace it before I could get the lid to seal.
 
OK , hmmm only 3/16" across. I have never cut one that skinny but, I don't think it will be to hard. If I get some free time tomorrow I will getter done.
 
I'm not trying to be a smart a$$ or anything but I'd hate to see you go through the trouble making a gasket 3/16" wide to find out you need one 3/8" wide. Have another look at the measurements.
 
If you subtract 9.875 from 10.25 you get .375 or 3/8 that is from total diameter. If you realize that 1/2 of that is taken up on each side of the diameter you will get that the ring of material is only .1875 or 3/16. Or 3/16+3/16=3/8, 3/8 plus the id equal 10 1/4 the od. The gasket cutter works on a radius. Punch a hole in the center a sheet that is over 10.25 and set the cutter at 5.1875 (5 1/8) then place the material on the center pivot when I turn the cutter wheel it will turn and cut the material, I will end up with a 10.25 disk. I will then set the cutter to 4.9375 (4 15/16) and when I cut I will end up with a disk of 9.875 and a 3/16 ring that is has a id of 9.875 and 10.25 od. I looked at the measurements.
 
Right you are. The first 2 scentences would have sufficed, guess at 2 AM I should think a bit more before posting :D
 
Its ok. lol. I can get a bit carried away. Part of the reason I want to get him lined out with a good gasket is I have a similar pot setting out in my things and want to work on the same type project when I get time. If I help him I can learn from his experiences. Seems like I spend more time working on equipment than Knives, but, getting to the point of having some first class equipment. The next project is rebuilting my kiln into a first class HT oven.
 
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