Replies

1. 
   hammer1 | May 17, 2006 10:52pm | #1

   I would worry about genuine pure tung oil. It likes to shrink and pull and wrinkle as it dries. A tung oil varnish will work. I'll leave your reasoning for this approach up to you. Always do a sample.

   Beat it to fit / Paint it to match

2. 
   SteveSchoene | May 17, 2006 11:18pm | #2

   I'd reverse the sequence.  A grain popping coat of oil (linseed oil cures faster and is only a little darker) should be used on bare wood so it penetrates.  Oils should never be allowed to build a film because the film would be very soft--almost gummy. 

   Shellac makes an excellent top coat, that would be substantially more protective than real tung oil.  By the way, lots of people seem to think that shellac is so fragile that one icey glass set down for half an hour will leave a ring.  It takes a lot more than that for water to hurt shellac. 

   Now you may not have real tung oil in mind.  Lots of the products on the market as "tung oil finish" contain no tung oil at all.  They are either varnishes--such as Formby's or oil/varnish mixes.  A varnish would be OK over shellac, but an oil/varnish mix would not--again the reason is that the oil content would leave a too soft film if it were on top of a sealed surface.  Oil/varnish finishes work nicely as an "in the wood" finish, with a modicum of more protective properties than pure oil alone. 

1. 
   forestgirl | May 18, 2006 02:37am | #6

   "A grain popping coat of oil (linseed oil cures faster and is only a little darker) should be used on bare wood so it penetrates."  Steve, this is what got me in trouble with the (stupid) maple piece I finished earlier this year, and I've yet to understand what the deal is.  Seems like everywhere I read, it's "pop the grain with tung/linseed oil, then follow with [whatever].  But I got blotching when I went straight with the tung oil (reduced 50:50 w/ mineral spirits).  Then I saw where Tom (our Tom, of long-bow fame) recommended a wash coat of shellac first. 

   Color me extreeeeemly confused.

   PS:  No, this wasn't highly figured stuff, but it did have some figure in it.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

1. 
   SteveSchoene | May 18, 2006 02:59am | #7

   Well, a wash coat should be very thin--1/2 lb. cut, perhaps.  And, I'd apply it almost as if it were an oil--but faster.  That is:  lay it on generously, but immediately wipe off any excess with a dry rag.  This will penetrate more on the open grain portions of the wood, and very little on the harder portions, hopefully balancing them out as far as subsequent oil penetration.  With such a light cut, the oil would still penetrate and not end up on the surface. (And, you would wipe off any that did.)  This is a little against the "rules" but it likely would work because it is just a wash, not enough to actually seal the wood. 

   The real question is where does figure begin, and blotch leave off.  In maple they are much the same thing except, I guess, that blotch is less regular. 

1. 
   forestgirl | May 18, 2006 04:05pm | #10

   "...where does figure begin, and blotch leave off.  In maple they are much the same thing...."  That was the impression I got, after this one experience.  Wood that's "lightly figured" seems to lend itself to problems not covered in the various books.  Back to "Wood Selection 101."forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

3. 
   PeteBradley | May 18, 2006 12:01am | #3

   Usually it would be the other way around.  What effect are you trying to achieve?

   Pete

1. 
   rickles13 | May 18, 2006 12:39am | #4

   Thanks for the reply...

   I'm using "General Finishes" Oil & Urethane topcoat, so not really just tung oil, over garnet shellac on walnut.

   The garnet shellac will be used to darken the walnut, I didn't want to use a wood stain or dye on the walnut, the garnet will darken it nicely.

   Then the Oil & Urethane top coat for the final finish.

   Thanks again

   R13

1. 
   SteveSchoene | May 18, 2006 02:22am | #5

   Contrary to the misleading marketing this is a varnish.  As a varnish it will work OK.  If it is what it appears to say, oil and varnish mixed, it won't work very well.  Frankly I hate it when manufacturers don't make it entirely clear what their product is.  That's one reason I haven't used this product.  That doesn't imply it isn't good, is just a statement about marketing. 

    

2. 
   PeteBradley | May 18, 2006 04:07am | #8

   OK, that's varnish over shellac. I've done that and it works great. You get the color and clarity of shellac with somewhat more durability. I did some tests a while back, and the resulting finish can still be damaged by heat and to a lesser extent, by ammonia. I use dewaxed shellac, but I've heard (never tried) that even waxed may work.Pete

1. 
   SteveSchoene | May 18, 2006 01:40pm | #9

   Your can put traditional resin oil-based varnishes over waxed, as well as dewaxed shellac.  It is polyurethane varnish that will only adhere to dewaxed shellac.  Waterborne finishes also require being applied over dewaxed shellac.