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Joined: Aug 2007
Posts: 87 Likes: 35
Sidelock
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Sidelock
Joined: Aug 2007
Posts: 87 Likes: 35 |
When buying varnish, as you've learned, it goes bad, always buy fresh, or test it first, if it doesn't cure correctly, take it back. I don't know what thinners/solvents Canada allows, but there are excellent varnishes that are thinned with only mineral spirits and maybe naptha. Normally, theres no need for any of the more unfriendly solvents in varnishes.
When you buy varnish for a wiping mixture, like you are using, make sure it is thinned with petroleum thinners, that way you will be assured they are compatible with linseed oil and mineral spirits. Not all modern varnishes are thinned the same, use the wrong varnish and you probably won't like the results. As an aside, turpentine is an excellent thinner for any oil based product. for some applications there is probably no benefit, but for example, thinning varnish to brush, it is much better than petroleum thinners.
Tim
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Joined: Feb 2008
Posts: 11,343 Likes: 390
Sidelock
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Sidelock
Joined: Feb 2008
Posts: 11,343 Likes: 390 |
I don't know about the low V.O.C. environmentally friendly varnishes, but the old stuff does not go bad in a sealed can. I have used old varnish that was heavily crusted over, and I used an unopened quart of Sherwin Williams Spar Varnish that was at least 40 years old, and they set up perfectly.
I have yet to see an expiration date on any paint, stain, or varnish product. But I am not impressed with any of the newer low V.O.C. finishes, and prefer to stock up on the old stuff when I can find it.
A true sign of mental illness is any gun owner who would vote for an Anti-Gunner like Joe Biden.
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Joined: Nov 2006
Posts: 3,436 Likes: 34
Sidelock
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Sidelock
Joined: Nov 2006
Posts: 3,436 Likes: 34 |
Some may be confusing varnish with shellac. Shellac does go stale when it sits too long, but old fashioned spar var is like Hostess Twinkies. If you dont open it, it will last for hundreds of years.
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Joined: Jan 2004
Posts: 6,715 Likes: 414
Sidelock
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Sidelock
Joined: Jan 2004
Posts: 6,715 Likes: 414 |
Are there any particular brands of Japan dryer that are preferred? Where would they be sourced?
_________ BrentD, (Professor - just for Stan)
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Joined: Aug 2007
Posts: 87 Likes: 35
Sidelock
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Sidelock
Joined: Aug 2007
Posts: 87 Likes: 35 |
I'm aware of the difference between shellac and varnish, although technically, shellac is also a varnish. In the 1800's, resins such as shellac, lacquer, copal and some others that were solvent in alcohol were called spirit varnishes. Resins that were combined with oil and thinned with petroleum or turpentine were called oil varnishes. Over time, terminology changed. Just like today, polyurethane is a varnish, but who calls it varnish?
Yes, varnish should last a while, but that doesn't mean it will. 20 years ago I bought a can of varnish, within one year I opened it to finish a table top, and had the same experience as Tamid, it refused to cure. With the exception of lacquer, it never hurts to test your finish before you use it, poor batches do slip out and some are adversely affected by time.
Tim
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Joined: Feb 2008
Posts: 11,343 Likes: 390
Sidelock
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Sidelock
Joined: Feb 2008
Posts: 11,343 Likes: 390 |
The second time I bought a bottle of GB Linspeed, it didn't set up. It was fresh and new, but remained sticky even after a couple weeks on my stock.
I'll agree that bad batches can slip out during production. I always assumed that batch of bad Linspeed simply didn't have the correct amount of dryer. In a way, I'm glad it happened because it prompted me to move on to better stock finishes, and to learn more about them. But I agree with Replacement that the older oil based varnish does not go bad in a sealed can, even after decades of normal storage. I'd be interested to hear what component might even possibly degrade under normal storage in a sealed can. I wouldn't advise anyone to throw out old varnish based upon conjecture.
A true sign of mental illness is any gun owner who would vote for an Anti-Gunner like Joe Biden.
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Joined: Aug 2007
Posts: 87 Likes: 35
Sidelock
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Sidelock
Joined: Aug 2007
Posts: 87 Likes: 35 |
Yeah, don't throw something out because its old, but definitely try it first. I seem to recall industry recommendations of shelf life of 5 to 20 or so years for varnish, but I'm going from a slightly faulty memory. But it can last longer, but I wouldn't bet stale bread on hundred year old varnish being any good.
As far as what goes bad, when it comes to petroleum, gasoline goes bad but I think mineral spirits is pretty stable. I would guess the resins are relatively stable too. On the other hand, linseed oil is a vegetable product. It might have a long shelf life, but I don't see it lasting forever. How long do canned vegetables last? The other question, do petroleum products affect its stability? I don't know.
Tim
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Joined: Nov 2006
Posts: 3,436 Likes: 34
Sidelock
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Sidelock
Joined: Nov 2006
Posts: 3,436 Likes: 34 |
Gasoline does not go bad if kept in a sealed container. Emphasis on sealed. That means zero exposure to atmospheric oxygen and atmospheric or other moisture, and zero chance of evaporation. Under those conditions, there should be no phase change. Although such storage conditions are difficult to achieve, it is possible. More info than you probably want: https://www.intechopen.com/books/storage...rage-conditionsThis is one paper. There are, of course, conflicting opinions. Under typical storage conditions, gas will go bad.
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Joined: May 2011
Posts: 1,136 Likes: 37
Sidelock
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OP
Sidelock
Joined: May 2011
Posts: 1,136 Likes: 37 |
Something is still amiss. I changed out the varnish and now it is not drying at all after 4 days. I'm strongly suspecting the Japan dryer since I have added more than the recommended dosage and it won't harden up the solution on the stock or in the bottle. I've set up two solutions of 1 to 1 linseed and dryer and 1 to 1 to 1 solution of turpentine, varnish and dryer. Will need to wait a day or so to see what happens. Here are the ingredients I am using at 1 part turpentine, 1 part varnish, 2 parts linseed oil and Japan Dryer at ratio of 1/4 tsp to 3 tsp solution.
Nothing is foolproof to a sufficiently talented fool.
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Joined: Nov 2006
Posts: 3,436 Likes: 34
Sidelock
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Sidelock
Joined: Nov 2006
Posts: 3,436 Likes: 34 |
Its gotta be the linseed oil. That looks like the art supply stuff. Go to a paint store and get BOILED linseed oil. You don t need a lot of dryer. Remember that your spar var and linseed oil mix does not dry the way paint dries. Once the solvents flash off, the oil polymerizes. Its a chemical reaction. On unfinished wood, your first application should be 60-70% solvent. Apply liberally, let it soak in, wipe everything off, and walk away until tomorrow. Repeat daily until finish starts to build. You can also wet sand the mixture into the pores after the first few applications. Start with 600 grit and work up to 1500-3000 grit, depending on how you want the finish to look. You can get the WD paper at any auto body supply or on Amazon. Wipe the surface dry after each application. Final finish should be IN the wood, not ON the wood.
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