I recovered three tree-ring disks from a 100+ year old tree that was recently cut down. I've sanded the disk down smooth and the rings and rays look really good. I would like to apply a finish to the tops to really enhance the tree rings while offering some form of protection at the same time.
I've used Varathane in the past on wood projects but these rings will be seeing a lot of hands-on activities so Varathane might not be the best idea.
Varathane just happens to be one variety of varnish (one containing polyurethane). I'd use varnish, but instead of Varathane, I'd use a good marine spar varnish (like McCloskey). Even tougher; a couple of coats ought to stand up to any amount of handling.
Don't use an oil finish as someone else suggested: too soft, and the wood will pick up dirt from handling. Varnish is the way to go; completely covers the wood, doesn't absorb dirt or oil, can easily be cleaned, and can be recoated later if needed.
Wait till it dries-months, maybe 6? or get a moisture meter and wait till near 15% or anything will peal. Gloss finishes are clearer alowing more grain to be seen. Marine poly if it will see sun outside.
Spar varnish is great stuff for spars, not so great for anything else. It is good for spars because they bend and spar varnish has a higher than normal amount of oil - the oil makes the dried film more flexible than normal but it also makes it softer.
Surface film depends on the amount of solids in the coating material and the thickness with which it is applied; however, two coats of anything other than catalyzed, poured material is insufficient to give a decent film that will last and protect for a reasonable amount of time. That is doubly true on end grain which is what the OP has.
Someone suggested waiting til the wood was reasonably dry. Good advice. Someone else suggested mineral oil. Not good advice as mineral oil *never* dries. Other oils such as linseed, tung, et al are possibilities but not great ones as they are pretty soft and don't offer much protection. Someone else suggested spar varnish; again, soft and not a good choice for this application.
Since you are interested in eye appeal and protection, oil based glossy poly (such as oil base Varathane) will give you both. The following steps will give you an eye catching finish...
a) wait until the wood is dry
b) make sure the wood is really well sanded - no swirl marks, feels silky smooth. Remove all sanding dust.
c) apply at *least* four coats of oil based gloss poly. Follow the directions on the can but usually you can recoat without sanding as long as the next coat goes on about four hours later. If you wait too long you need to let it dry completely then lightly sand before applying another coat.
d) let the last coat dry at least 48 hours (longer is better) then rub it with #0000 steel wool. Do so until all glossy spots are gone. If you cut completely through the finish anywhere, stop, apply two or more additional coats, let dry another 48 hours then steel wool again.
e) apply one more coat of finish. The only purpose is to bring back the shine so apply it thinly - thin a bit and either brush or wipe it on.
You could do the same thing with either regular alkyd varnish or lacquer. Both are less scratch resistant than the poly and lacquer will not "pop the grain" as much; the latter is also true of water based poly.
"The Ranger" wrote in news:4OidnQENXaxd83TVnZ2dnUVZ snipped-for-privacy@posted.rawbandwidth:
it depends on indoor or outdoor use. for outdoors;use a marine finish,that will have UV protection.
indoors;shellacs and oil finishes will not protect against water rings from drink glasses.
you probably want to apply some sort of stain first,to enhance the grain,then seal with urethane,lacquer,or varnish.
Remember you are dealing with END grain. it will soak up a lot of finish if not stained/sealed first. the first coat will probably raise the grain,and then need a bit more sanding.
I wasn't planning on using any oils for those very reasons; 2nd and 3rd graders tend not to wash their hands very carefully, nor do they care if they're washed very carefully. :)
What will happen if I apply the Varathane to green wood?
I've been sanding them over the last week; the tops are silky-smooth and the rings and rays are really beautifully detailed, almost eye-catching from across the room!
I remember having to do this with shelac when I was in wood shop (3 decades ago) but I thought Varathane frowned on being rubbed with steel wool...
Thanks for the step-by-step! I appreciate the details.
They'll be used for classroom exploration in a 2-3 combo class. As a result, I want something that will assist in keeping the rings pen(cil) free, while also enhancing the durability of the wood. I remember seeing a tree disk from a redwood that had this clear varnish finish all around it when I was a young kid; me and several classmates spent many a fun hour counting rings, and working with it. It was almost a self-contained theme lesson: history, math, science...
The downside is the disk weighs in at 20 pounds so if I add too much more weight to it, I'm simply asking for someone to get hurt.
Thanks for the reminder about end-grain soaking up unless sealed; I'd forgotten about that lesson the last time I learned it.
Spar or Marine rated is the only thing that will hold up against UV rays and take the expansion -contraction that happens outside, for doors its the best. I have jobs that 20 yrs later P&L marine is fine, a door in winter can go from 0f-70f when the sun hits it in winter in an hour, expanding the door measurably.
Yes, a "marine" spar varnish would be good for that application since hardness can be sacrificed for flexibility. If you're getting 20 years though, you are lucky. Very lucky. I used to have a sailboat with a yard (horizontal spar), always finished with a high grade "marine spar" alkyd varnish. The top of the spar was good for maybe 6 months in tropical sun.
AFAIK, spar varnish need not have UV inhibitors. Not likely since it is generally used in an environment that needs to have UV filtered. When a manufacturer tosses in the word "marine" it is generally to indicate that a UV filtering material has been added. Given the propensity of manufacturers toward puffery, it is always a good idea to check the label for the actual contents.
Dunno, never done it. Best guess is poor adhesion and failure as the wood dries and shrinks. ______________
Not AFAIK, I do it. Not as easy to rub down as lacquer or alkyd varnish though. I also do it with #400 or #600 wet or dry silicon paper used wet. The advantage (?) of steel wool is that it conforms to surface irregularities (they always exist) and you are less likely to cut through. Be sure to get any steel fibers off, a magnet is useful. People advise against steel wool with *water* borne finishes because any residual pieces of steel will rust. ________________
That's true, and I should have caught that. End grain soaks up any finish like crazy, so it'll take as many coats as it takes to completely cover the wood, no matter what the material used.
I ued to use P&L the stuff that cost $70 a gallon in the early 80s, alot of churches and school doors. On boats I worked on life was maybe 2-3 years since it is a harsher invironment with near full day sun and constant flexing. McClosky and others only lasted me 5-10 years. Do you apply it in sun or a hot surface by chance, I know on a boat its hard to get proper shade to varnish, even sun to soon after is hard on it. I would have though by now chemistry would have improved upon P&L marine.
Your project might benefit from applying some boiled linseed oil to accentuate the ring pattern before proceeding with finishing. You apply and wipe off after 5-10 minutes. Let dry several days, longer if the weather isn't so good. This is standard with pine/shellac finishing. I think it might be beneficial with varnish as well and your wood. If you have a surface you can experiment on, so much the better.
Assuming you use varnish, I'd recommend at least 3 coats. What you choose depends on the usage. Will your pieces be exposed to weather/sun?
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