I'm no scientist.........but what I’ve learned is that once you open a can of finish and expose your content to air, the oxygen allowed inside the can will react with your finish and begin to harden. It starts as a thin film but in time turns into a gummy gel that basically ruins a portion or perhaps all of your remaining finish.
I"ve written before on ways to store your oil-based wood finishes like urethanes or even paint, but admittedly found only limited success …. until now!
Without a doubt the best way to store finishes is by using Bloxygen: an inert gas that “eliminates thickening and skin-over.”
Bloxygen provides a layer between the air and the finish that protects your product.
My “go to” finishes are General Finishes Arm-R-Seal semi-gloss for my spindle turned pieces and GF’s Wood Bowl Finish (or SBF: Salad Bowl Finish) for my bowls.
These finishes work so well that I get many compliments from my finished products, yet at roughly $13 a pint or $20 a quart they are costly enough to want to get every drop for your dollar.
The problem with most small shop owners is that we don’t use these every day, so storing them properly for the next use is important. Countless times I’ve come back to a half-filled, well-sealed can only to find the remainder of my product transformed into a useless gel.
Bloxygen (at about $12 a can) has fixed this. You have to do the math to see if it’s worth it to you, but I’ve found it to be cost efficient. The can is about 9” tall and feels like its empty, containing .41 oz of gas – but they claim you will get about 75 uses in quarts. I haven’t counted out the number of sprays I’ve used but their claim is likely accurate.
My method is simple: I take a new can and pour a useable amount into a smaller container. I’ve found that clear plastic prescription medication bottles work well enough for the project at hand, so I can spray a couple blasts of Bloxygen into the larger can and seal my lid, leaving it perfect for the next use.
This method works well even for the prescription bottles I use. Simply tilt the lid slightly open, spray a few “shots” into the bottle, and twist on the lid. Although these are not airtight containers, they seal well enough for me to get 3 or 4 coats of finish on my wood piece while keeping my primary container from continuously being reopened.
If you want something that works, give Bloxygen a try! The company claims it preserves stains, varnishes, chemicals, resins and more. The Prodigal Carpenter says 2 thumbs up!