Replies

1. 
   UncleDunc | Feb 24, 2004 03:56am | #1

   What do you hope the tung oil will do for you? Are you talking about 100% tung oil, or is this a tung oil finish, which is basically an oil base varnish.

2. 
   chise2 | Feb 24, 2004 09:03am | #2

   Shellac can be top coated if it is de-waxed shellac. Shellac in a can, I believe, has wax. But why put tongue oil on now? The wood is sealed by the shellac, which by the way should dry very hard. The oil can't penetrate. Would it even dry? One might put tung oil on bare wood to penetrate and bring out the figure in the wood. Then when that's dry, top coat with shellac.

3. 
   erich | Feb 24, 2004 05:09pm | #3

   Hi JR,

        I'm an acknowledged beginner in the finishing department, but what I have accomplished in the past sounds like what you've done so far.  I constructed a set of humidors and sealed them with a couple of coats of de-waxed shellac, that brought out the figure a good bit, then top-coated with lacquer.  I don't think the oil would do you much good now, and might not go on as well as you'd like.  Maybe tell us what you're trying to achieve with the top-coat.  Durability, thermal resistance, "Natural Feel"?  That might clue someone with more experience than me to suggest something that might be better suited to your application.

                        Good Luck,

                              Erich 

1. 
   scooter1 | Feb 24, 2004 08:59pm | #4

   Shellac can be merely a sealer coat or part of a top coat.

   If you want to apply something over the Shellac, then by all means you may. Anything sticks to Shellac. I think I would probably rub out the Shellac or apply a hard wax.

   Regards,

   Boris

   "Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934

4. 
   ChasStanford | Feb 24, 2004 10:09pm | #5

   If I was you, I'd spray lacquer then come back behind that with some Watco Danish oil, and follow that with a good wiping varnish....

   I assume you know that this is tongue-in-cheek. 

   The only thing you need on top of shellac is a little paste wax.

   
   

   ---

   Edited 2/24/2004 5:19:11 PM ET by CHASSTANFORD

5. 
   HowardAcheson | Feb 24, 2004 11:45pm | #6

   Let's clear up a number of things.

   First, shellac will fill the pores of the wood. Oils work by being absorbed into the wood, not by sitting on top of the wood. In other words you first apply the oil, then you apply a film finish like shellac, not the other way around. Applying tung oil to a surface already sealed by shellac would be like applying the oil to a pane of glass.

   Second, lacquer would seal the wood just like shellac. Watco is an oil/varnish product and just like tung oil, it would not be able to penetrate the lacquered surface. It would sit on top and just be gummy or completely wiped off when you do the wipe off stage. Oil/varnishes need to be applied to virgin wood.

   Third, the only finishes that can not be applied over shellac containing wax is oil based and waterborne poly varnishes. Those require dewaxed shellac. Any other film finish can be applied over any shellac. Standard oil based varnish and lacquer can be applied over shellac containing wax.

   Finally, shellac is a very hard finish. It is harder than most varnishes and poly varnishes. As long as it is applied to a solid surface, it will make for an excellent finish.

1. 
   b1gcountry | Feb 26, 2004 02:00am | #8

   Well said, I agree with you, but have one question...

   Do the oil/varnish blends really behave differently than a pure varnish. I always thought of them as a form of thinned varnish. I don't use either due to poor dust control (shellac mostly), but if the oil/varnish blend can form a film coat on top of itself, will it not form a film coat over shellac?

   Tom

1. 
   HowardAcheson | Feb 26, 2004 05:05am | #9

   >>Do the oil/varnish blends really behave differently than a pure varnish.

   Yes, an oil/varnish is a mixture of varnish, a drying oil (generally boiled linseed oil) and a thinner (generally mineral spirits). The typical mixture is equal parts of each. The intent of oil/varnish is to penetrate the pores of virgin wood and dry into the wood, not on it. The varnish in the mixture effectively seals the pores after the first coat preventing any further absorbsion of subsequent applications. In addition, you wipe these products dry as part of the application. If the pores are sealed by the first coat, the action of wiping dry will remove virtually all of the wet coat. The oil content, if not wiped dry will cure somewhat but it is a very soft, gummy finish. Put some Watco on a non-absorbent surface like glass. Let it dry for 4-5 days. See how soft and wrinkled it is.

   Now an oil/varnish finish is a nice finish for many applications. The one area I would not use it is for something like a kitchen table. I have used it very successfully on other tabletops that do not get much abuse. It is a very nice, in-the-wood penetrating finish that is much like a true tung oil finish but more durable.

   A thinned varnish, is simply varnish thinned with a thinner like mineral spirits or naphtha. For all intents and purposes it is a varnish finish except it dries to the touch in a few minutes. When the thinner evaporates, you are left with exactly the same finish as you would get from full strength varnish, only a thinner film. So, with thinned varnish, you need to apply more coats to get the equivilent film thickness. Unlike the oil/varnish finish, a thinned varnish finish is an on-the-wood film finish.

   Both the oil/varnish and the thinned varnish work very well in dusty situations. The oil/varnish you wipe dry and the thinned varnish becomes tack-free in a few minutes.

1. 
   VeniciaL | Feb 26, 2004 10:45am | #10

   Howie,

   Your description of the oil/varnish process is not exactly correct. The mixture is allowed to sit on the wood or on previous coats for some period, then wiped "dry." Just because the word "dry" is used does not mean that all the finish is actually removed from the surface. Although it is thin, a film DOES build. The film is mostly varnish. After the 2nd or third coat, the finish builds quite a bit with each application, especially if the finisher learns to wipe so that a wet-looking, but almost immediately-dry film is left.

   The film build of an oil/varnish finish, done correctly, while not in the league of French polishing, is lovely. It is also very durable and long lasting. And it shares French polishing's other attribute - it can be repaired to look like new very easily.

   VL

1. 
   b1gcountry | Feb 26, 2004 06:46pm | #11

   So it sounds like the subsequent coats do not benefit much from the oil in the oil/varnish mixture one way or another. Do many oil finish users wipe on a coat of oil/varnish for the first coat or two, and then follow up with a build of straight varnish? What would the benefit of this be compared to wiping on some BLO followed by a straight varnish?

   I almost always use Shellac, sometimes followed by wax, or preceded by BLO, but I know little about oil-based finishes since I stopped using them due to dust nibs, and clarity issues (Minwax poly and polyshades ruined one of my pieces).

   Thanks,

   Tom

2. 
   Gretchen | Feb 26, 2004 07:48pm | #12

    I stopped using them due to dust nibs, and clarity issues (Minwax poly and polyshades ruined one of my pieces).

   Reinvestigate this finish using 50/50 wipe on varnish (not poly varnish).Gretchen

3. 
   VeniciaL | Feb 26, 2004 08:07pm | #13

   Big country,

   Nothing matches shellac for clarity, brilliance and surface sheen. I use French polishing for most of my finishing. But when I do an oil/varnish I just use "Minwax Tung Oil Finish." It's as good as any other such concoction, proprietary or home-brew. It's a combination of some varnish, some oil (mystery- probably linseed/tung) and solvent.

   I just wipe it on the raw wood, let sit, keeping it wet for 20 minutes or so, and wipe it off. Subsequent coats I apply with 4-0 steel wool. Wipe on, wipe off with rag prepared almost like a French polishing rubber. Wiping becomes a little more "special" with coats beyond # 2. With practice, I've learned to leave the surface "looking wet" but actually so thin a film that it's immediately dry to touch.

   Beyond about the 5th coat is the point of diminishing returns, although some finishers put on much more with additional benefit.

   The ease of application is a trade off with the time required to achieve a good cure and "polish" to each coat. Don't rush it. At least 48 hours between coats, sometimes MUCH more - up to a week.

   If French polish has a sheen of 97 on a scale of 0-100, the oil varnish is 88-90. Same with clarity/brilliance.

   VL

4. 
   chise2 | Feb 27, 2004 12:19am | #14

   I'm not sure I follow you. As Howie said after the first (or maybe second) coat of an oil/varnish the pores of the wood are sealed. With subsequent coats any build would have to be from the varnish, as you said. So what is the point of using oil in the mixture after the pores are sealed?

   Why not, as big country suggests, use straight varnish, (or thinned varnish to get the control, thin coating, and quick dry time), on subsequent coats?

   Does the oil actually dry because it is mixed with the varnish? Or does it prevent the varnish from drying as well as it would with out it?

   Why not apply straight oil (or thinned for penetration) to the bare wood for a coat or two to get the "deepening" effect that oil is supposed to give. And then wipe on thinned varnish for durability and a film finish look?

5. 
   Gretchen | Feb 27, 2004 12:43am | #15

   I think this mix actually becomes a (very) long oil varnish and does eventually dry.Gretchen

6. 
   UncleDunc | Feb 27, 2004 01:54am | #16

   Straight varnish has oil in it. Some varnish has more oil and is called long oil varnish. Some has less and is presumably called short oil varnish, although I've never actually heard that phrase used. A varnish/oil mix is not different in kind from straight varnish, it just has more oil.

7. 
   Gretchen | Feb 27, 2004 03:14pm | #18

   Examples of long oil varnish are marine varnishes--they are softer and more flexible.  Poly is a short oil (and yes, that is a term) and therefore is harder and more brittle, susceptible to chipping.Gretchen

8. 
   VeniciaL | Feb 27, 2004 07:19am | #17

   Chisel,

   "So what is the point of using oil in the mixture after the pores are sealed?"

   Simply because it works!

   Not being a finish chemist, I can't tell you exactly what's happening on the raw, partially sealed or fully sealed wood. I don't think the wood is sealed for a few coats - maybe it is after the 3rd. Maybe not.

   The oil/varnish mixture works well and it's just as easy to stay with it as to switch to some other brew for coats beyond the first few. I've become familiar with it, and in finishing that's important. I think the oil serves as a lubricant in this type of finish, even (and especially) after the wood IS fully sealed, which contributes to the final effect I get.

   Ultimately each finisher settles on a few routines which work right under a given set of conditions. With a finish that takes weeks to start looking really good, I don't like surprises.

   Now get me talking about French polishing . . . THAT'S finishing!

   VL

6. 
   Alan | Feb 26, 2004 01:39am | #7

   Jr,

   What Howie said!

   Alan