Preserving oxygen cured finish like varnish

That reminds me...

John in NM

About a year or 9 months ago I tried an experiment using a couple cans of BLO. One was a quart paint can, maybe 1/3 full and the other was a gallon can like paint thinner comes in, about 1/4 full.

The question at the time was whether welding CO2 would also work or whether the finish would absorb excessive amounts and crush the cans. I used some pure CO2 that we use for cleaning optical elements at work, sprayed some in each can and sealed them. There was noticeable contraction of the cans over the first month, though it was mild, about what you get with a 7000 foot altitude change - seal a plastic water bottle on a picnic in the mountains and its shrunk a little when you get home.

That said, if one doesn't have a mig set up, the nitrogen bottle looks like the way to go. I used to work for a pro shop that used a lot of Waterlox, they were always re-bottling it in jam jars the boss brought from home and then adding marbles or whatever to take up space as the finish was used up. Only reason that worked well is that we used it up pretty quickly!

you did an experiment I have wondered about

Bill Tindall, E.Tn.

Thanks

CO2 will be soluble in varnish....but how much? Apparently not enough to be a problem, unlike propane and contact cleaner. One could, I suppose, use dry ice.

Re: you did an experiment I have wondered about

William Duffield

Wouldn't you have a problem with the sealed can bursting as the solid CO2 sublimed?

Re: Preserving oxygen cured finish like varnish

Don Stephan

Before it was discontinued this spring, I was having the same issue with quarts of Pratt & Lambert 38 varnish. Spraying Bloxygen into the can every time it was opened did not avoid gelling.

Another wood turner told me about Stop Loss bags

www.stoplossbags.com

if I didn't make a typing error. They are I think pretty widely available at woodworking supply stores and mail order sites. They worked well with the P&L. When I opened a can of Waterlox Original a few months ago I poured it into a Stop Loss bag, but until I saw this thread I hadn't thought to check on it. Will try to remember to check tomorrow.

various comments

Bill Tindall, E.Tn.

1. I encourage you to investigate Waterlox. It looks about the same and PL38 but it dries to a much harder finish. I was surprised how soft PL38 was and it took a month to fully cure at that.

2. If you had displaced the oxygen the finish would not have gelled. The directions on the can imply that way less squirts are needed than in fact. It isn't cost effective. I don't think the bags are either. They are pricy unless reusable.

Do not return finish to the storage container. Setting out while brushing it has picked up a load of oxygen and the start of cure has begun. Removing oxygen from the head space will not reverse the curing that has begun. It will in time gel the entire container.

Re: Preserving oxygen cured finish like varnish

Don Stephan

My error, I did not transfer the contents of the quart can of Waterlox Original to a Stop Loss bag because I did not have an extra one on hand. I am still evaluating the performance of Waterlox on a daily cereal bowl.

Over the last couple years I have emptied and refilled a Stop Loss bag with diluted and full strength P&L 38 several times with no apparent degradation of the bags. It can be tedious to coax small air bubbles to the top of a Stop Loss bag prior to closing, and I try to have the finish extend at least part way up the 1/4" long nozzle to minimize oxygen exposure.

My overall experience with the Stop Loss bags and funnel are very positive.

inert gas

John K Jordan

I'm glad to see you finally got a tank set up. I've been using a tank of nitrogen for this for years now and it still has plenty of gas, however mine are larger tanks, "Q" I think. Fortunately, nitrogen is cheap. When this one runs out I have a spare argon tank I think I'll try.

I used to leave my tanks at the supplier for filling but now I just swap them for a filled tank - it's the same price and takes just one trip, and as a bonus the tanks are always current with hydro testing.

Argon not cheap anymore

Bill Tindall, E.Tn.

I got the word on Argon. It is a byproduct of making oxygen, that once was made in vast quantities to feed a common steel making process that used it. Now days there is so little steel making that in places air is liquefied, nitrogen and oxygen recovered, and oxygen vented back to the atmosphere (I was told at supplier). Hence, argon has gotten more expensive. The cost was more than I was willing to pay for little benefit to my use.

Re: various comments

david weaver

I use the bags, but admittedly, for varnish that I've made. My varnish is dammar, pine, flaxseed, a little tiny bit of strained maple ash water and true turpentine. It dries like crap unless exposed to a huge amount of sunlight, and it also has a reputation of not lasting at all once it's exposed.

I couldn't say exactly how old my varnish sample is - 5 months? 6 months? It's completely fresh. I can't see why the bags couldn't be re-used with like finishes if they were mostly emptied.

The costs are on a different scale with house made varnish - it's about 50 cents a milliliter on the open market and I expect that making 20 ounces of it probably costs me $35-$40. George tells me that it's relatively little trouble to add driers if needed to speed it up, but none of those are probably particularly healthful. They would be mandatory for furniture building, but with instruments (that hang veritcal), I can wait for sun, and the hand done look is an in thing with guitars right now.