Replies

1. 
   Rich14 | Mar 02, 2007 07:00am | #1

   Will,

   Use an oil-based silex pore filler - Behlens Por-o-Pac is the standard, get the mahogany brown variety. It will have no problems with the stain/sealer coat (which should be dry and hard first). Don't use rottenstone the Behlens product is much better.

   In fact an option is to mix the mahogany pore filler with the tung oil and use that mixture as the pore filler/stain/first coat of finish. You apply it exactly as you would just filler. Flood it on, scrub in with the grain into the pores, let it change from a wet slurry to a leathery-looking suface, then, across the grain, scrub it and scape it completely off, leaving filler in the pores. You'll need to experiment with scrap, but it may give you the look you want in one step. If not use the sequence you described.

   Rich

2. 
   SteveSchoene | Mar 02, 2007 04:27pm | #2

   I see several questionable points and one serious problem.  Starting with the latter:  the oil/varnish mix is not appropriate with the pore filler.  Oil varnish cures quite soft and mustn't be allowed to build on the surface. But over a surface sealed with a pore filler it can't help but build to a film.  If you fill the pores you really need a top coat of a film finish, either varnish, shellac, or lacquer. 

   Why tung oil?  Compared to boiled linseed oil it takes forever to cure.  And before you apply a top coat over a pore filler made with tung you must let it really cure.  A month would not be too long.  Tung doesn't buy you anything with mahogany compared to BLO except being slightly lighter--as if you could tell once you put a dye with it. 

   I would definately go with a commercial pore filler.  More transparency and fewer potential problems. 

   Let me through out a finishing schedule for mahogany that I have used to give an attractive antique looking mahogany with a hint of the gold highlights that marks the old cuban mahogany. 

   I start with a medium yellow dye on bare wood.  Don't throw up. Then I partially sealed with about 1 lb. cut shellac, applied as if it were an oil finish except at lightening speed.  That is, apply liberally and then very, very quickly wipe it off.  A two person act would be good if your table is large.  Then, when the shellac is dry, check for any thick spots or grain that has raised and sand those off with 320 sandpaer or a card scraper kissing the surface.  It won't look much better at this stage.  The next step is a second coat of dye--this time using brown mahogany of what ever color you like.  Don't go too dark here--the wood will darken over time, and there is another color step to go.  When dry, apply a second coat of shellac normally.  I use about 1 1/2 lb. cut here.  You want to seal, but not so much that the sealer interfers with the bonding of pore filler. 

   Then I use the pore filler if I am going for a full filled surface (if not, a pigmented stain works instead.)  The pore filler should be tinted with pigment--either Japan colors or good artists oil paint.  For mahogany I use a mix of burnt umber and burnt sienna.  Adjsut the ratio for your tastes.  Apply the pore filler and rub off excess cross grain just as it hazes up.  If you have a large table do it in segments--the overlap won't be a problem.  This both fills the pores and deepens the color.  Usually the filler is mixed to be a tad darker than the base dyed woods, but interesting effects can be had by lightening the filler or altering the color.  Let the pore filler cure for at least a week before applying top coats--longer if your finishing area is below 68° or so. 

   Shellac makes a good top coat for traditional mahogany.  Alternatively, a good traditional resin varnish, such as Behlen Rockhard or Pratt & Lambert 38.  Let this cure a month and rub out to whatever sheen you like. 

3. 
   Rich14 | Mar 02, 2007 06:40pm | #3

   Bill,

   I agree with Steve about using shellac on mahogany. In fact, I usually wind up recommending shellac over almost any other finish (except certain lacquers in specific situations).

   You said you wanted to use tung oil, so I kept my answer oriented to that. Why don't you take a few scraps and try each way, then decide which is right for you.

   Are you using "real" tung oil or a product labeled "Tung Oil Finsh?" Unless your tung oil is labeled "pure" tung oil, it probably is not tung at all, but a proprietary mix containing linseed, not tung! If you have pure tung, make sure it is also partially polymerized, or it will take forever to harden.

   Rich

4. 
   frenchy | Mar 02, 2007 07:51pm | #4

   w_b

    let me chime in here to support Rich 14 on the shellac finish..

    Traditional finish on Mahogany was always shellac. Shellac has a depth and richness you'll find in virtually no other finish.  Shiney without looking  plasticy.   Shellac can be done inside of two hours and then you are ready for the final decision regarding what your next step is..(usually polishing) 

    If you are comfortable with shellac then please go ahead with whatever process you usually use.. if not and you are worried about runs, drips, and brush marks let me give you a simple & easy way to eliminate the risk of having them.

      Before you are frightened off. let me say that I am without a doubt the worlds worst and messiest painter! Give me a paint brush and you have a mess..

    Yet with shellac I can quickly do flawless brush work!  The reason is that shellac thins out beautifully with denatured alcohol.  There really is no limit to how thin you can thin it.. and what's more thin is great for shellac!

    I'll gladly give you the simple process if you'd like..

    What's more if you don't like the results you can simply wipe shellac off with no harm done..

    

    

    

      

       

1. 
   w_b | Mar 02, 2007 09:48pm | #5

   Frenchy, Rich, Steve,
   Thanks for the input so far. I used to build then give to a friend that finishes..but, I've moved and now it's time I should learn!I can't tell if the Tung oil is polymerized, but it is Tung..just doesn't say anything else.So lets say I'm going to Shellac. I would be interested in any foolproofed-ness you might be able to add Frenchy as this will be the 1st time. I've always done oil, varnish and oil/varnish before, only not on mahogany and never over filler. I like the schedule that Steve suggests, so step-wise?
   -yellow (I've already got TransTint amber so maybe that) dye
   -sealcoat of 1lb-cut shellac
   -brown mahogany dye (I have this in a Tung-ground dye)
   -1 1/2lb-cut shellac
   -tinted pore-filler
   -shellac topcoatHow about the shellac, my choice or would you recommend seedlac, amber, orange?? Also,
   Any issues with the dyes? One is TransTint and the other is Tung-ground.Out of my depth here...and the waters seem very deep with this subject.--Will

1. 
   Rich14 | Mar 02, 2007 11:08pm | #7

   Pretty much agree with Steve. There's no mystery in applying shellac. I spray it, but brushing is not hard. Do not try to "paint" with it. Brush it on in one direction and leave it alone. You will get lap marks. Don't try to deal with them with wet shellac on the brush. Leave them be. They will be removed by leveling with sandpaper.

   A 2# cut is a good concentration. I scuff sand after each coat with 320 grit (others don't). The first coat raises the grain (unless a sanding sealer is used - then it raises the grain). When completely dry (an hour or two, I wait overnight) scuff sand lightly with 320 on a sanding block, taking down the nibs and grain and tops of the shellac "mountains." The "valleys" will remain shiny and untouched. Do not try to get them all, you will sand through the thin shellac coating. You know shellac is dry and hard enough for leveling if sanding produces a perfectly dry, fine powder.

    Apply another layer. Each application completely disolves into the previous. Let dry. Scuff sand. The mountains will come down very easily and result in wider areas of abraded shellac. The shiny valleys will be a little smaller. 

   Apply again. Let dry. Scuff sand. With each application/sanding the abraded areas will become much larger, eventually merging and eliminating the valleys. After many such applications (3-6 perhaps), when gentle sanding easily produces a uniform, ground glass appearance of the entire surface, you have finished the application/leveling process and can begin to rub out the shellac surface.

   Rubbing out can consist of wet abrading with 400, then 600, then 1000 grit or with 4-0 steel wool for a soft matte appearance. Or can continue with automotive rubbing compound (red), polishing compound (white) and swirl remover for a beautiful, glass-like appearance.

   Rich

2. 
   tom77 | Mar 03, 2007 05:34am | #8

   Will,

   I think you have received some really good advice here and I don't have much to add to that.  Except for one bitter experience:  I used a combination of BLO and pumice as a grain filler on a mahogany table top. (after reading a FWW article)  I let it cure for only a couple of days before beginning the varnishing process.  Two months later, several white spots about the size of a nickel showed up around the perimeter under the finish varnish coat.  The spots were the pumice turning white after the BLO completely cured.  (The varnish only slows the oxidation process)  The areas were all around the perimeter, indicating that I had not completely wiped off the excess slurry. Based upon this painful experience, I strongly support the use of the off-the-shelf grain filler and letting it cure thoroughly before starting to apply the finish coat.

   Good luck, Tom.

1. 
   w_b | Mar 10, 2007 09:17pm | #9

   Definately. Thanks, guys.Well the route I've gone so far is,
   -Amber stain
   -BLO and stain mix (brown mahogany with a little red mixed in
   Looks very nice.waiting for that to dry and then I'll follow up with the oil-based grain filler (thanks for the tip on not using pumice!)One final question,
   Should I use a Shellac washcoat over the current BLOw/stain before applying the OB pore filler..or does it really matter?Once the grain filler is in I'll brush garnet shellac to finish.Thanks again,
   Will

1. 
   Rich14 | Mar 10, 2007 09:44pm | #10

   Will, If you use tinted pore filler (and it has to be tinted) without sealing the wood (partially or fully), the pore sealer mix will further stain the wood. That may or may not be what you want. It's usually not wanted at all, but all the options in finishing are completely the choice of the person doing the job. The only way you can decide is to carry out all the finishing steps on scrap, first. Rich

2. 
   SteveSchoene | Mar 02, 2007 10:30pm | #6

   The thin, thin thin doesn't really work in this context where a more formal fully filled finish is sought, and that's the context of the question asked.  You can get shellac too thin to control the dye penetration, or to control how stain or pore filler will affect the color.  These situations call for more controlled applications of shellac.  And, three 1/2 lb. cut applications won't give the kind of rich, mellow gloss finish over filler that shellac is capable of providing.  Nor, will it give enough meat to rub out the shellac to a satin sheen without starting to cut into stain or filler "layers".  To do this takes building some film thickness. 

   Controlled application of shellac isn't some mysterious process that takes a lot of skill.  But it does take a little care and the right equipment.  A good brush is called for.  The best are watercolor or watercolour wash brushes with the synthetic bristle called Taklon gold.  The bristles are very fine, and the brush doesn't hold a lot of shellac.  It allows applying very even layers where overlap doesn't matter much, and which don't contain so much liquid shellac that they risk dissolving lower layers so much that bad things start to happen.  Fast and sure is the key.  Just keep moving, never go back to a fill a missed spot or brush out an overlap,  and if you sense any drag of the brush over the finish stop and let lower coats dry some more.  A good pad, with no wrinkles in the cover, can accomplish the same thing, and some find it easier.  I think an absolute tyro can pick up using either brush or pad in a few 15 minute sessions, spaced over a morning. And the results are worth it for the flexibility it adds to using shellac. 

   With three coats of very thin shellac you are limited to an "almost film" that looks much like an oil finish when used on open pored woods such as walnut or mahogany.  It's a very nice finish, but not what you see on formal furniture, particularly of traditional style as one might find in museums or up scale living rooms.