Has anyone got a workable solution to the film that forms over the varnish in the can or jar?
I’m using Pratt & Lambert #38, which is a great finish, but which will form a film in the can in little over two hours. Over night, and it’s a nice thick film. It’s easy enough to remove, but I’d like to avoid it.
I’m assuming that it’s the varnish reacting with the oxygen in the air in the can that’s causing the film.
Since I’ve read that propane was the propellent of choice for many spray cans, I’ve tried eliminating same by filling the open space over the can with propane gas from my plumber’s torch, thus expelling the air and it’s oxygen. (Yep, I taped the mixer orifices closed so that I got just gas and not a gas-air mixture). Regrettably it films over just fine under propane.
What DOES work?
Mike D
Replies
You can try a spray called Bloxygen. You can get it from most of the usual woodworking supply suspects. Lee Valley carries the same thing in a house brand: http://www.leevalley.com/wood/page.aspx?c=1&p=30268&cat=1,190,44133&ap=1
I haven't done any real comparative testing, but it seems to help. I spray it into my Waterlox cans, which will skin over if you just turn your back for a moment.
Incidentally, you can get exactly the same stuff, sold as a wine preserver, at various supermarkets and other food outlets.
-Steve
Is the wine preserver sold for a lower price than Bloxygen?
Since Pennsylvanians have to go to a state run store (sounds kind Soviet Unionish) to buy wine and other types of alcohol, except for beer, I can't say I've ever seen it in any local grocery stores.
And not consuming any other adult beverages than beer, I haven't been in a state store for a long time.
Well, Mike found some for $7, which is lower than I've seen for Bloxygen anywhere. It's usally around $9-10.-Steve
Is your varnish a polyureathane based one? If so, water will catalyse the curing so you would need to try and eliminate water vapour.
Maybe attach a packet of freshly regenerated dessicant to the lid?
Many varnishes have been reformulated to reduce their VOC emissions. These varnishes will more rapidly skim over than the older formulations. Those marketed as "fast dry" are the biggest offenders.
Some things to do are to only open the can for the least amount of time. As always, pour off what you need into another container, close the original tightly and work out of the other container. The longer the can is opened, the quicker the material will begin to react to the oxygen.
Cans with less than half of their contents will react faster due to the greater amount of oxygen in the air above the contents. Pour contents into a smaller container and tightly seal it.
Once a finish has already skimmed over, it has begun to deteriorate. You can't really reconstitute it like you could in the olden days. It has begun to oxidize and while it may look good, you may have curing problems with the finish. It's best to buy only the finish you need and if you want to save leftovers, date the can and discard it after a couple of months.
Hi Howie,
Peter Gedrys says that I should thank you for your thoughtful and informed response. And I do! :)I tossed my older, mostly empty can of P&L and finished up my project with a fresh can. I was very gratified by the improved flow-out and rapid curing experienced with the fresh can. This is what I had remembered liking so much about P&L when I first opened the original can.I also found that Wine Preserver (AKA Bloxygen) works like a charm in preventing the varnish in the can, and in my working bell jar, from skimming over. This should help both in maintaining the high quality of the working product, and extending the life of the remaining product in the can.
Marbles. Seriously. Just plop them in until the varnish level is displaced back to the top of the can.
Well, as always I'm learning a lot here.I have know about Bloxygen, but haven't been able to locate it locally. The suggestion to look for a similar product at the wine store worked out very well - I found it at the local Liquor Mart. The wine version is not pure argon - it also contains CO2 and nitrogen, but should work the same. I'll post here in a couple of days to let you know how it works. It's cheaper than Bloxygen - only $7.50 a can.I didn't know that, once a film started forming in the can, basically the contents of the can are toast. That surprises me. It certainly makes sense, but I'd like to have that confirmed by another source before I start throwing away (good?) varnish. In the case of Pratt & Lambert #38, that's an hour after you crack the lid on the can. Ditto on the amount that I pour off into the Bell jar with which I use to load my brush.Thanks for all the great input!Mike D
Edited 7/5/2008 4:55 pm ET by Mike_D
"The wine version is not pure argon - it also contains CO2 and nitrogen..."
So does Bloxygen. The formulas are identical.
-Steve
Ah,so.
Cool! and thanks.
Mike D
Mike,
I just finished a game table finished with PL#38, and had no drying or other problems till I got well below half of the can, after pulling off a top skin 3-4 times. The last time, the remaining material had started to gell throughout, and at that point I got a new can. No problems till then, in my limited experience ( I'm a Finishphobic ). I was using a wipe-on method, not brushing, which might make a difference.
Well, I've asked Peter Gedrys for his take on this issue, but he hasn't seen my question, yet.I am not experiencing jelling per se of the finish under the skim film, but on the other hand, the finish in the older can's viscosity seems to be up, as the last coat that I applied left distinct brush marks and thick/thin places and had to be sanded back rather aggressively. Just to be on the safe side, I put my older (two month old, and now 1/3 full) can of Pratt & Lambert #38 aside and opened a fresh one for the final coat on a face frame I'm finishing. I was surprised at how much better the varnish from the fresh can flowed, and, after 3 hours, the surface is flawless and already safe to touch. I won't move it and attach it to the case until tomorrow, but I am pleased with this final coat.What a lot we learn from each other.
Mike DP.S. I've now used the Wine Preserver on both my new can of P&L and on the sealable bell jar that I'm using as my painting can. I am happy to report that there is no sign of a surface skin in the bell jar, which is only about 20 percent full. Without the WP or Bloxygen, I typically would already see a skin on the finish in the bell jar.Mike DEdited 7/6/2008 4:38 pm ET by Mike_D
Edited 7/6/2008 4:40 pm ET by Mike_D
For something important, definitely better safe than sorry. The cost of the varnish is a lot less than the aggravation of refinishing. I'll have to try that bloxygen next time.
Woodcraft is supposed to carry it, but I have never been able to find it on the shelves at my local store. I can vouch for the fact that the Wine Preserver sold in some wine shops is cheaper (at least here), has the same formula, and works like a charm! One thing to note - the can feels empty when you pick it up - it's not, so don't think that it's leaked out.
Mike D
>> I was using a wipe-on method, not brushing, which might make a difference. Had you already thinned the material? You will find it best to only thin what you plan to use that day. Don't thin the whole container. Once thinned, it begins to oxidize much more rapidly.Howie.........
Thanks, Howard. Finishing is my weakest point, I'm trying to pick up pointers wherever I can
I may be old school but I've always just sealed the container tightly and then stored it upside down. If any skin does form, it's at the bottom of the container. That said, I won't use any finish that is more than 12 months old.
I would rather spend the $8-10 on beer!
Regards,
Ron
"I would rather spend the $8-10 on beer!"God forbid you would have to drive and go get it.By the time you got to the store you would have burned up all your beer money in gas.However, I'll take a can of beer over a can of air anytime.F.
This may sound like an almost too simple solution, but you could try putting a layer of plastic wrap on the surface of the varnish.
This would keep the oxygen from ever reaching the surface of the varnish at all! I would test to see if it reacts with the solvents in the varnish first though.
Chaim
Make your own mistakes not someone elses, this is a good way to be original !
That's what cooks do to keep a film from forming on custard, for example, while it cools. It works but it's messy, as you might imagine. It's also not clear how you would ensure that the plastic wrap stays in place inside a can.
-Steve
Steve,
What a great opportunity to make your next million bucks...
What about a springy thing that you'd insert into a can, have it spring open to seal against the sides of the can, and then could be easily removed? The spring could be re-covered with new plastic wrap each time it is used.
I await your design specs..
ZoltonIf you see a possum running around in here, kill it. It's not a pet. - Jackie Moon
I'll stick with Bloxygen, thanks.
-Steve
You cut it a bit oversized and avoid shaking the can too much!
But I'm sure bloxygen will work also.
ChaimMake your own mistakes not someone elses, this is a good way to be original !
An alternative to Ed's suggestion of marbles -- which I've used and work just fine -- is to cut a circle of waxed paper and float it on top of the liquid.
I learned that from our neighbourhood handyman in the late fifties.
LOL, when someone accused me of having lost my marbles I showed em! I just opened a can of varnish and there they were.
I've heard of using waxed paper as you suggest, but I've never tried it. I've kept varnish amazingly long in a cup covered with saran wrap in the fridge. The freezer works too, but you've got to give it time to warm up.
Simplest is almost always cheapest and best.
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