Shelf life of Cetol/Epifanes

[Jonathan316]

Could anyone tell me the approximate shelf life of an opened can of Cetol, Epifanes, or other quality wood varnish?

Assuming the opened can is sealed & stored properly at a favorable temperature, just how long can I expect a can to last? At $30 a quart I''m hoping it will last a long time if stored logically.

Thanks!

[elhanley]

I was interested in this same subject as regards Cetol Gloss. I thought it would be useful on my oak bar at home, and put on a coat of some four year old stuff I had on hand. That was over three weeks ago, and it has not completely cured out yet, although it gets harder allthe time. I was wondering whether it was due to its age, or some reaction with the previous finish.

[Sasha_V]

many specialist coatings and paints hae some very volitile components to aid with either penetration of the surface or with flash-drying (creating a touch-dry surface).
These volitile components will evaporate fairly quickly in warm conditions if the tin is left open, but even if closed, once oxygen has mixed in (the more space in the tin the more oxygen) the products will break down over time (depending on tempreture, product, amount of air that got into the can and time).

It could take 6 months for your bar to fully cure and it will be sticky and suseptible to damage for nearly every moment of that time (an will aquire a lovely coat of dust o dull the finish).

Sorry.


Sasha

[HeartofGold]

There are a number of products available to woodworkers which my extend the shelf life of varnish once opened. They come in a spray can and contain heavy inert gasses. By injecting them into the cracked lid of a can of varnish, it the heavy gasses settle and push out the O2. Blo2xygen is the trade name which comes to mind, but I recall seeing several other brands.

I have not yet tried these products on marine vanishes, but have speculated for some time that I should invest in a can if these products work half as good as the manufacturers claim.

Doug

[Jonathan316]

FWIW, if you do a Google search for "cetol shelf life" you will come across some wide-ranging answers.

I think Sasha and Doug are right on the money. But through the Google you''ll find mentions of people who (wrongly) say it will last for years. One guy basically said "if it forms a solid cap in the can after a few months just cut it off and it will be fine". Gasp...

Sasha or Doug, do you know if there is some sort of chemical need to package quality varnishes in only quarts and above? Not seen any pint containers of the high-grade finishes and wondered if it was because a minimum quanity is required to maintain a proper mix of the elements or something like that.

Jonathan

[geohan]

We have often thought it would be nice to have the varnish or paint packaged in a collapsing bladder within a box, a la some wines. You would have to ''knead'' the bladder to mix the paint but varnish doesn''t need mixing and no air contact, no skin. We have placed plastic wrap over the surface of the left over varnish or paint in the can. It does pretty good but is messy. We haven''t tried using a "ziplock" bag yet but maybe that is next.

[elhanley]

I swear there is not anything you can ask this board that will not produce a number of useful answers. As for my Cetoled bar, as I said, it gets better all the time. The surface was non-tacky very promptly, but a pin scratch exposed gooey stuff underneath. Now, after three weeks, the surface is quite hard and smooth, but if I leave a glass sitting on it overnight, there is just a bit of stickiness if you try to slide it along the surface. I am sure it is approaching final cure - maybe hyperbolicly. Is that a word?

[Sasha_V]

I am in Australia. But at our local chandlery, Cetol can be bought in cans of 250mm and upwards.
It is much cheaper in the 4litre cans and such, and so most people buy the larger amounts for the extra "value" figuring that they will use it all "sometime".

After a while, I can see a chandlery deciding to just not stock the smaller sizes which do not sell and take up valuable shelf space....

One of the things that I have done when buying stupidly expensive varnish in 4litre cans was to immediately decant it into empty (and clean !) 600ml coke bottles that I had wrapped in duct-tape to make them light-proof. Fill all the way to the top and seal.

That way, I got a LOT more life out of the varnish. I think I openend the second last bottle a couple of months ago...about 3 years after purchasing the 4ltr tin. It was still perfect.

The decanting can be a messy process, though



Sasha

[HeartofGold]

There are two other methods of preserving partially used cans of varnish:

1) Once a can is partially used, add marbles to the can. This raises the level of the varnish so that less air (O2) settles in the container.

2) Along the same lines, once a can is used and the level is low enough, I almost always filter the varnish, drain and store in a smaller (1 pint) container. It is my expericence that if I leave this in a 1 quart container, a skin begins to form at about the half full level, leaving just enough to fill a 1 pint container. I have stored these single pint cans of filtered varnish for more than a year without ill effects.

Doug

[Jonathan316]

Wanted to thank everyone for their comments and close the thread with a couple of other tips my research on this found.

Doug''s marbles tip is excellent, and apparently kinda common in the kayak''er community. If stored on board your boat with marbles, you also increase the "agitation factor" to keep the product from settling and/or separating over time. It also discourages the formation of "hard drips" in/on the lids of the can.

Apparently the key to very long storage is simply removing the oxygen in the container; like marbles do. But there are also products like "Finish Preserve", a combination of nitrogen, argon and CO2 which you spray into the top of any paint, stain or varnish can to preserve the contents. The computer cleaning spray "Dust Off" can also be used in the same context. Some people use butane, propane or other flammable gases. Yipes.

Professional varnish/stain folks seem to prefer simply holding their breath and blowing into the can as they cover it with plastic wrap. Then mount the lid over the wrap and store the can upside down - and at an angle. Read of that technique being used to store Cetol and other (like Sasha says) stupidly expensive varnishes for over 5 years without noticeable degradation or skimming.

Epifanes taught me that the best way to store those expensive badger-hair brushes is to leave them suspended in diesel fuel or kerosene. Give them a quick rinse in mineral spirits before and after storage. I imagine it makes for some stinky but well-kept brushes.

Last, seems that the best container for volatile varnish is glass or cans. Some use Ball jars with extra lids (Sasha''s suggestion of wrapping in duct-tape is a good one there too), or small solvent cans (tins) available real cheap over the net at places like woodfinishingsupplies.com and others. Seems that everyone advises to store them upside down and/or tilted on angle.

With a combination of those tips in your pockets I feel reassured that you can safely store stupidly expensive varnishes for a very long time for lots of miserable brightwork days.

Thanks for the help!

Jonathan