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Bloxegen substitute?

bill5335's picture

I've used Bloxegen to keep the varnish in the can from skinning over, which seemed to work as advertised. The can says it is "inert gases".  I'm no chemist, but I know that Bloxegen displaces the oxygen, preventing oxygen to react with the varnish.

I was wondering if CO2 or nitrogen would work as well as Bloxegen?    (For the sake of discussion, assume I have a safe way to deliver the gas to the varnish can.)


Any chemistry folks out there?

TXJon's picture

(post #107678, reply #1 of 38)

I don't have an answer, but I would like one too. 

I have tried propane (on the general consensus of some on this forum who usually seem to know what they are talking about).  Propane proved to be completely useless, maybe even worse than nothing.

I used it on a half full quart can of oil based paint.  Just a few days later it was completely skinned over.

I have a gallon can of Waterlox I have been using for over a year, and the Bloxygen does indeed work as advertised.  Not cheap, though.

JohnWW's picture

(post #107678, reply #2 of 38)

Bloxygen is a mix of nitrogen, argon, and carbon dioxide, none of which have any special properties that I know of except that they'll flush oxygen out of the can and they don't react with finishing materials. 

I've had excellent luck using the dust remover sprays sold for cleaning photo and computer equipment, they're basically one of the freon substitutes, R-142 I believe.  A can costs around $4.00 at Walmart, it's in their photo section, and by weight it contains 18 times as much material as a can of Bloxygen.  The trigger on the dusters is also easier to use than the one on the Bloxygen cans.

John W.

John White Shop Manager for FWW Magazine, 1998 to 2007

WayneL5's picture

(post #107678, reply #19 of 38)

Even though you could make CO2 with baking soda and vinegar, the gas will have lots of moisture and some acid vapor in it.  Moisture is not good for some finishes, and the acid may not be good for some, either.  So a different source for the gas would be wise.

CharlieD's picture

(post #107678, reply #3 of 38)

I use CO2.

I've never used Bloxygen, but Co2 seems good enough. I mix vinegar and baking soda--two cheap supplies if there ever were any--in pretty much any reasonable proportions; I do this in a Pyrex measuring cup because it has a spout. The mixture bubbles off pure CO2. CO2, being heavier than air, can be poured if you go slowly. Once the mixture quits bubbling, I pour the invisible contents slowly into the finish container, being careful not to spill any of the leftover mixture into the can. That's it; I don't worry about it filling the entire void, because since it's heavier than air, my logic says that even a thin layer of CO2 should block the air from the varnish.

You can test this. Mix the two supplies in any old container. After is stops bubbling, light a match and lower it into the container; it will be snuffed for lack of oxygen. Then slowly pour into another container the same size; lower a match into the 2nd one, and the match will be snuffed, proving that you've poured CO2 into the 2nd container. DON'T do this test with a can of finish, of course!

Good luck! Works for me.


I tell you, we are here to fart around, and don't let anybody tell you different. --K Vonnegut
A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects. - Robert A. Heinlein
nikkiwood's picture

(post #107678, reply #4 of 38)

I read the first couple of posts in this thread and was about to trot out the vinegar/baking soda concoction -- which I read about recently in an old woodworking mag.

You tell us how to test it, but does it really work -- in terms of keeping a skin from forming?

*** "It is what we learn after we think we know it all, that counts." John Wooden ,1910-2010

highfigh's picture

(post #107678, reply #5 of 38)

If you need more CO2, a 1/2 gallon milk jug would work, too. Probably collect more and if you need some later, it can be capped off.

"I cut this piece four times and it's still too short."

"I cut this piece four times and it's still too short."
CharlieD's picture

(post #107678, reply #7 of 38)

It does work for me, but I haven't tested it in any specific way, like for example, using my CO2 in one container and regular air or some other product in another. Certainly there may be finishes that will react with CO2, but it's pretty stable. I really haven't had problems. The Bloxygen is readily available, affordable in the long run, less messy, easier to use, yahda, yahda, yahda. If your'e worried in any way, it's only 10 bucks. I just can't be bothered to aquire a can of the stuff.


I tell you, we are here to fart around, and don't let anybody tell you different. --K Vonnegut
A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects. - Robert A. Heinlein
EdHarrow's picture

(post #107678, reply #6 of 38)

If you have access to N2, that will work OK, tho perhaps Ar would be better (heavier than N2).

The low-tech method is marbles.  Dump in enough that the varnish is brought up to the top of the can.  You can use them over and over if you keep them out of the dirt and dust.

Jon_Cummings's picture

(post #107678, reply #8 of 38)

Any of the inert gases on the Periodic Table should work. They are safe and that is why they are called inert.

These elements will "displace" the O2 in the can of finish. CO2 is a compound and it really displaces not breath it ! CO2 is also in fire extinguishers and "diplaces" the O2 around a fire and a fire can not burn without O2. I would not recommend using a shop fire extinguisher to keep finishing products from skimming over or you may not be able to put out your fire:-)

                                      Sorry for the Extraneous Comments      Dick

AlanMikkelsen's picture

(post #107678, reply #9 of 38)

These finish preservers are a bit of a sore subject with me.  I haven't used Bloxygen, but I've used the Lee Valley equivalent, and I still get major skimming over.  I've used a couple of cans, apply plenty, but the finish still skims.   <unhappy camper>

Alan & Lynette Mikkelsen, Mountain View Farm, est. 1934,  Gardens & Fine Woodworking, St. Ignatius, MT

Alan & Lynette Mikkelsen, Mountain View Farm, est. 1934,  Gardens & Fine Woodworking, St. Ignatius, MT

Jon_Cummings's picture

(post #107678, reply #14 of 38)

I use Southerland Welles tung oil products @ $32 + a quart. They go a long way but will turn to jelly in no time. So.....what do I do to keep the product fresh for as long as possible?

A. Pour the quart contents in smaller tightly capped jars (baby food jars, canning jars, cheesewhiz jars etc. etc.) and fill them to the top so that no/minimal O2 will get in.

B. use only one jar at a time. Do not leave it open while applying finish. Rather, pour a small amount of finish in a small container like a "frozen pot pie" plate.

C. Put marbles (I still have mine) in the partially filled jar to bring the level close to the top. Then I use bloxygen.

I also use bloxygen when I fill the small jars.

Previous responses to your original question have given most every thing I can think of.

                              Good Luck            Dick


bill5335's picture

(post #107678, reply #10 of 38)

A paint ball expert told me I can get a cartridge of CO2 for about ten bucks.  I haven't tried it yet, but I'm sure I can attached a pressure regulator and valve to dispense into the can. 

I would have tried marbles, but my wife said I lost them a long time ago ;-)

HowardAcheson's picture

(post #107678, reply #11 of 38)

Any non-oxygen gas will work just fine. Propane will work fine. Just stick your torch nozzle under the lid, open the valve for a second or two and quickly close the lid. Propane is heavier than air so does not rapidly escape. Old timers used to just exhale into the can and slam on the lid.

The key to preserving finish is to only open the can for the time required to decant what you need into another container. Keep the can closed and, of course, never work from the can and never return unused finish to the can. Date you finish and discard any remainder after 4-6 months. Buy only what you need. Using old finish is a false economy.

tailsorpins's picture

(post #107678, reply #12 of 38)

For CO2, try the mail order/Email bicycle shops (Nashbar or Performance)for the CO2 inflators they sell.  Select one with a trigger, and one that encloses a standard CO2 cartridge for piercing.  Caution: some of these devices dispense the whole cartridge at once, and some others use only special cartridges that are threaded .... neither is desirable.  With care, one cartridge will last several years -- it only takes a minimal amount each time, however you might find that control is difficult to achieve, and you might "blow" the contents all over the shop!  I use one because I had it in my bikekit and lots of cartridges for an air rifle!  All that said, the "duster" sold at Wal-Mart seems the most reasonable and least costly solution.


JohnWW's picture

(post #107678, reply #13 of 38)

As an EMT we were taught that we only absorb a small portion of the oxygen in the air we breathe, so that an exhaled breath has almost as much oxygen in it as ordinary air.  If this weren't true CPR wouldn't work.

John W.

John White Shop Manager for FWW Magazine, 1998 to 2007

tted's picture

(post #107678, reply #15 of 38)

As a lab chemist, we inert reaction vessels with gas virtually all of the time. Argon is the preferred displacement gas (because it is even heavier than nitrogen) although we almost always just use nitrogen.

Carbon dioxide is a reactive molecule which is why I'd avoid it for general use. Sealed up, it dissolves into water and is present as carbonic acid. In fact, carbonated beverages are simply liquid solutions with a large amount of CO2 dissolved in them.

Propane is relatively inert, but it also seems like a bad idea. It is miscible (mixes well with) the kinds of hydrocarbons present in most finishes. This means you're basically diluting your finish with solvent. Maybe not a practical concern in many cases, but I don't like running experiments on my finished pieces. Besides, you're just upping the overall fire hazard level of our already hazardous shops!

As an aside, I brought a solvent safety cabinet home from work. It was considered defective because one of the leveling feet was broken. I sawed it off, and now I have a perfectly functional 4' tall, 4' wide, 18" deep cabinet. It is absolutely full - and I can't even fit the cans of latex paint in! I have more flammable solvents at home than I keep on hand in my organic chemistry lab.


redrock1's picture

(post #107678, reply #16 of 38)

I have a can of thedust remover and istates that it contains difluoroethane. CAS#75-37-6 whatever that is. To the chemist mavens, does that sound right?  I just got my order from Lee Valley including a can of "Finish preserver" maybe I should return it when I return something else?


AlanWS's picture

(post #107678, reply #17 of 38)

Difluoroethane should work fine, though it's MUCH more expensive than CO2, which would also work fine. The higher density of the gas is helpful while you're adding it, but a layer of gas over the finish is completely useless in protecting it from air in the container. All gasses mix.

When you add inert gas to the finish, you want to not only fill the container, but flush out all the oxygen. Think of the air as cranberry juice, and the CO2 as beer. Imagine you have a keg, but the only mug in the house is full of cranberry juice. You can't dump out the mug (that would be equivalent to using a vacuum pump to remove air from the finish before adding CO2: it'd work great, but it's not likely you have the equipment.) So you need to add beer to the full mug, letting the mixture overflow until the mug is full of beer. No matter what you do, the beer and juice will mix, so you need to add a lot more than one mugful before the last traces of red color (and flavor) are gone from your beer.

So the way to flush the finish can is to make sure you get as much air out as possible, and to seal it without letting air back in. One way is to use a thin tube under the cap to flush for a while, then slip out the tube and seal quickly. Another is to put the open can and cover into a large plastic bag, and flush gas into the bag to fill it and flow until the air is rinsed out, then put the top on the can while it's still in the bag.

Propane could work, but it will dissolve in the finish. The main problem with propane is that in order for it to be effective, you'll need to flush a lot into the air and that's dangerous indoors since it can burn. Outdoors it sounds OK. Inert gasses (CO2 or hydrofluorocarbons) are much less dangerous, since you would need an unreasonably large amount to flush enough air out of a room to make you suffocate. The advantage to CO2 is that it's cheap enough that you are more likely to really flush out the air thoroughly, since it's the lack of air that prevents skinning over, not the presence of the gas. A CO2 fire extinguisher or a soda siphon could work well.

Carbonic acid can form from CO2 and water, but there's not much water in oils, and that acid would not be a problem. Water base finishes don't need protection from the air.

JohnWW's picture

(post #107678, reply #18 of 38)


In theory the difluoroethane may be more expensive than inert gasses, but the reality is you can buy 14 ounces of difluoroethane packaged as a dust blower for around $5.00, and the nozzle and trigger control is perfectly designed for gently flushing out a can of finish.

By comparison, Bloxygen is selling a 3/4 ounce can of nitrogen, argon and carbon dioxide mix for more than twice as much.  The price advantage of the difluoroethane is around 35 to 1.  In addition, the control valve on the Bloxygen makes it hard to smoothly control the release of the gas.

I've done several controlled tests comparing Bloxygen to difluoroethane and in each test the difluoroethane was at least as good if not better than the Bloxygen.  A five second spray of the difluoroethane in a pint jar with just a 1/2 inch of fresh Waterlox in the bottom will still be as good as new after sitting a week.  In the same test, the finish in the Bloxygen filled jar will have just slightly thickened and the Waterlox in the air filled jar will have formed a thick skin. 

I discovered in my testing that once a finish has formed a skin over it, it will inevitably all turn to gel no matter how it is treated afterwards.  This is true even if you strain off the thickened surface layer and the remaining finish appears to be fully liquid. 

This result confirms the guideline that you should never contaminate a can of finish by working directly from the can and never return unused finish to the can.  It also means you should start using a flushing gas as soon as the can is opened.  If you wait till the finish starts to go it is too late to stop the process. 

John W.

John White Shop Manager for FWW Magazine, 1998 to 2007

AlanWS's picture

(post #107678, reply #21 of 38)


That sounds reasonable. When I said the disadvantage of difluoroethane was the much greater price than CO2, I didn't mean to compare it to the absolutely absurdly priced bloxygen. Since most of the price is the bottle and nozzle, CO2 might not be cheaper to use even though $5 would buy you something like 10 lb of CO2.

Your observation that once an oil starts to skin over, it will cure even if you protect it from air makes sense. That should hold for finishes that use oxygen from the air to cure, (but not those that use water, like silicones and some urethanes.) Oxygen actually can inhibit polymerization at first, but as it does so it forms peroxides similar to those you add to polyester resins to cure them. Once peroxides are present, it is heat that causes the cure, and more oxygen is not required, though its presence can make more peroxides for a faster cure. So yes, the most important time to flush the air out of the finish is when it is fresh.

Alan S.

AlanMikkelsen's picture

(post #107678, reply #23 of 38)

Thank you for this information.  I've been less than pleased with the Bloxygen/Lee Valley preservers.  I'm going to steal a couple cans of computer duster from my wife and take them to the shop.

Alan & Lynette Mikkelsen, Mountain View Farm, est. 1934,  Gardens & Fine Woodworking, St. Ignatius, MT

Alan & Lynette Mikkelsen, Mountain View Farm, est. 1934,  Gardens & Fine Woodworking, St. Ignatius, MT

Gretchen's picture

(post #107678, reply #31 of 38)

Interesting thread and I will be looking into the dust remover. I might suggest also, after carefully wiping your can lid, doing all this, invert the can to store it.



eganders1's picture

(post #107678, reply #32 of 38)

Is a possible alternative MIG gas?  It has argon and CO2 in its mix and I hardly ever use my MIG welder, so it would be a good use of the gas.

AlanWS's picture

(post #107678, reply #33 of 38)

If that's all that's in the MIG gas, it sounds like an excellent choice. Just make sure to flush it enough.

Biscardi's picture

(post #107678, reply #34 of 38)

I have been using uranium tetrafluride. It works great but my hair is falling out and my gums won't stop bleeding.


upstateBill's picture

(post #107678, reply #35 of 38)

Could you tell me if difluoroethane is the same as tetraflororthane. That is all I find in cans. Thanks.

UncleDunc's picture

(post #107678, reply #36 of 38)

Chemically similar, but not the same as.

tms's picture

(post #107678, reply #37 of 38)

Difluoroethane is sold as Freon13. Tetraflouroethane is Freon152. Freon 152 is about twice as dense as Freon 13, but the boiling points are about the same.

For your purposes, no difference.


bobpowers's picture

(post #107678, reply #20 of 38)

Be sure the lid is on tightly. Turn the can upside down. I have had paint and varnish in my shop for years with no skin.

WCunnigham's picture

(post #107678, reply #22 of 38)

I saw this solution in some woodworking magazine so I cannot take credit for ingenious solution - kudos to the orginator - sorry I do not remember the name.

For wine drinkers, there is usually a empty wine bottle sitting around - so wash it out and let it dry. Transfer the extra varnish, oil ,etc to the empty bottle. Use the a wine saver vaccum system (vac - q - van is an example) to vaccum seal the material. This effectively removes the amount of oxygen in the atmoshpere above the liquid - which is the same effect of the blow agents. Extra stoppers are about $1 each and they are reusable. Of course this give a use to that present (wine saver) that someone gave you because a true wine drinker never has an unfinished bottle of wine to save.