Finishing question

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On my current project (red oak hallway table) I was aiming for a filled-pore, stained look. I used a blend of water-based aniline dyes (walnut and rosewood) to get the colour just right.
Then I brushed on my first coat of water-based acrylic finish and took almost all the colour off. (Damn!) This didn't happen on my test panel, but still I probably should have expected that a dye that dissolves in water would also dissolve in water based finish. I managed to get it so there aren't streaks, so the piece looks OK (the friend I'm making it for doesn't know the colour I was aiming at, so the colour I got will do just as well).
However, in hopes of never experiencing this pain again, I thought I would ask for your advice on how to avoid it. I can think of some ways:
1 - Spray the finish. I think it was the act of wiping the wet brush over the surface that took off the dye and that a spray coat of stain might not have caused it. However, this would require a spray booth and a bigger compressor, both of which are problems. Anyway, I'm not sure it would work. If I sprayed finish onto a vertical surface, it seems like it might dissolve the stain and cause it to run downwards.
2 - Sack up and use oil-based polyurethane. I hate and fear oil based finishes, not least because my shop is right next door to my furnace room, but it might be time to learn.
3 - I have read that a thin coat of dewaxed shellac can be used to seal the stain in the wood, and then water-based finish can be applied over it. Has anybody tried it? Are there problems with the finish curing improperly, or peeling, or otherwise failing?
4 - Somebody will suggest just not staining the wood, and instead buying wood that is naturally the colour I wanted. I am seriously considering it for next time. :)
- Ken
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Ken McIsaac wrote:

Often!
No. You get the bonus of much less grain raising, along with slight ambering, which makes the WB finish look like an oil version.
My favorite is ML Campbell Ultrastar (WB Lacquer), over Zinnser Sealcoat. The Sealcoat replaces Ultrastar Sanding Sealer, use one or the other, or you risk too thick of a finish. I spray it all with a Fuji HVLP gun, using a suction or pressure feed cup with a #3 setup, or a #4 with a gravity cup. I prefer "Dull" for most furniture, which has more gloss than you'd expect.
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#3... almost.
If you stain with water based stains, then after staining you can coat it with dewaxed shellac before applying a water based film finish. Same goes for if you use an oil based stain, you can use shellac as a barrier for oil\solvent based finishes.
Shellac is pretty much able to go under anything and is the end all for setting a barrier for sap, fungus\mold, blending of finish and stain, etc
If you seal the wood first the color won;t take much. It can be a strategy with very thinned shellac or lacquer for woods that blotch, to make a more even coloring but it has to be real thin and won't helop the blending of the next coat if it a solvent of the color.
You said "Pore filled" but didn't mention when\how you will do the pore filling. I would suggest a black grain filler for oak, since your color sounds dark. I would put it on after the shellac and before the acrylic or after the first coat of acrylic.

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Ken McIsaac wrote:

Whatever the finishing question, the answer is shellac :-).
Dewaxed shellac is a great barrier coat between almost any other finishes. Just be sure it's dewaxed.
Of course, it's a great finish in and of itself as well.
-- It's turtles, all the way down
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On Fri, 11 May 2007 16:37:56 -0700, Larry Blanchard
Almost any finish except shellac!
I'm trying to do some japanning at present. I'm having such bad results with shellac that I might have to switch to using genuine urushiol lacquer, despite the cost and complexity of handling it. I'm trying to get a decent thickness built up over an uneven surface so that I can sand it down flat and smooth, but every layer disturbs the underlying layers too much.
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Andy Dingley wrote:

Are you using a brush? I apply shellac with a pad - 3 or 4 cosmetic pads wrapped in cotton or linen. Takes more coats but they dry faster so elapsed time is about the same. Requires little or no sanding as it's pretty smooth as is.
I never had much luck with a brush. Even with a retarder, the stuff dried so quickly that lap marks were a problem. It may have just been my technique, but it was so much easier with a pad that I've never felt the need to do any more experimentation with a brush.
--
It's turtles, all the way down

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Larry Blanchard wrote:
> Are you using a brush? I apply shellac with a pad - 3 or 4 cosmetic pads > wrapped in cotton or linen. Takes more coats but they dry faster so elapsed > time is about the same. Requires little or no sanding as it's pretty smooth > as is. > > I never had much luck with a brush. Even with a retarder, the stuff dried so > quickly that lap marks were a problem. It may have just been my technique, > but it was so much easier with a pad that I've never felt the need to do any > more experimentation with a brush. >
SFWIW, had similar problems with 2 lb shellac.
Cutting it to 1/2 lb seems to solve the problem.
Again, more coats, but less aggravation.
Lew
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On Sat, 12 May 2007 16:02:19 GMT, Lew Hodgett

I usually just spray it. Spray cans are always on hand for jobs too small to justify messing up the gear.
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Additional layers of shellac won't disturb the underlying layers as much if each layer is dried thoroughly before the next layer is applied. I usually put my parts out in the bright sun for a few hours to get them really dry. Then spraying on the next coat is the best way to minimize disturbance of the previous layer. In bad or winter weather this won't work, but I haven't needed to face that situation yet.
--
Charley

"Andy Dingley" < snipped-for-privacy@codesmiths.com> wrote in message
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3 lb cut, straight from the can. My favorite 15 year old Linzer black china angled sash brush. Use it with latex, I'll murder you.
Load the brush, lay it on heavy, work fast -- takes me about 30 seconds to lay one coat on a 32" threshold strip. Don't try to fill in skips while the coat is wet. Let that wait for the next coat. Sand or scrape down any high spots after they dry. Sand uneven coats level if you're not happy. 320 grit flooded with mineral spirits works fast.
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I think you should be using a clear grain filler or something else to flatten a surface but not just the film finish. I have laid down enough lacquer to flatten Oak to a piano type finish or even easier poly but it is nevr as flat as doing a proper grain fill and the finish is really susceptible to cracking and crazing.

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Oil-based poly looks only slightly less like you varnished with Elmer's Glueall than waterborne poly. For a tabletop, try Behlen's Rockhard, a phenolic resin varnish that looks more like lacquer.

Shellac is _the_ sealer.

Varnishes can be tinted with artists' oils to any color you like. The palette of just four earth pigment colors, raw and burnt sienna and umber, can be mixed to match any wood color known.
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On 12 May 2007 13:41:33 -0700, Father Haskell

Some of the better water based lacquers look as good as Rockhard, and may be even more chemical and heat resistant.
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Any specific brands? Water-clear and dead, or slightly (and pleasingly) ambered? Is the feel closer to lacquer or to Elmer's glue?
I can blend Rockhard with tung or linseed to make a first-class oil-varnish mix. Not sure I can do that with waterborne (which is still oil-based, being made from a petrol-based plastic resin, emuslified with a glyclol type "bridging solvent; "water-based" is technically incorrect).
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On 13 May 2007 12:52:37 -0700, Father Haskell

ML Cambell Ultrastar

Slightly ambered, but not as ambered as solvent based. I use Sealcoat as a sanding sealer, in place of WB Sanding Sealer, and a few drops of TransTint amber dye to help it a bit.

Just like the ML Cambell nitrocellulose lacquer I also use. I've got five gallon buckets of both on hand pretty much all the time. _IF_ you pay attention to the film thickness. Hose it on with a fire hose, and it'll get thick looking. The NC stuff is much better on cherry.
This stuff IS NOT the same as water based, home center or paint store polyurethane. Not even in the same league. That stuff is Elmer's Glue...
I'm not anti-solvent based, but I have to go elsewhere to spray it in a proper booth. I can spray Ultrastar in my basement or on an occupied site without explosion risks, Fire Marshall hassles, or clearing a 50 mile radius. It dries in minutes, just like NC lacquer, and it is plenty rubbable.

Probably not, but I don't see why you'd want to. If I wanted a very thin oil-varnish mix, I still use an oil-varnish. It's just that this stuff is incredibly easy to use and possibly more durable. <G>
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On 12 May 2007 13:41:33 -0700, Father Haskell

I must confess my ignorance. I know they are chemically different, but in appearance aren't polyurethane and lacquer both just slightly amber, transparent polymer films that can be rubbed out as glossy or flat as you want? I can imagine that they might feel different, or age and wear differently but you can tell them apart just by looking?
Thank you to everybody who replied. It seems that next time I should indeed seal with shellac first, no matter what comes after.
- Ken
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You can get water poly that is dead clear or with ambering. NC lacquer has natural ambering and other lacquers all have some amber when new or over time.
The biggest differences is in how hard and how easy to rework. Ploy is hard shit. Once its setup its done. Yes you can rub it out from gloss to satin, but it takes much more work and is not nearly as nice or even a finish. Also, poly is not soluble after it dries.
Lacquer is softer or brittler (is that a word?) but rubs out much easier and nicer. Also super fast drying so easy to be productive and avoid dust nibs. Also soluble after it dries so it is "more" fixable than poly. I say "more" because it is hard to repair either but you have a better chance with lacquer.

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More brittle?
Hard = brittle. Elastic = tough. Tool steel is made less brittle by tempering it, which makes it less hard and more elastic. Really good swords can be bent 180 degrees without snapping, and will return to dead straight when released.

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Lacquer is water-clear, closer to shellac than poly. Poly is used for toughness -- that means it's soft, and soft coatings can't be rubbed out. Lacquer or shellac rub out to a higher sheen. Lacquer's big advantage over shellac is water and alcohol resistance. Its main disadvantage is its solvent's toxicity and volatility.
Use what's most appropriate, and it varies. For kids' furniture, poly is perfectly fine. For your better work, shellac or lacquer if you want a film finish. Amber shellac is hard to beat, especially on pine or red oak. Poly lends a cheap look like nothing else.

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Depends on the shellac. Garnet shellac is... well... garnet colored. Blonde is blonde, etc. And lacquer is only clear if it is water based, CAB, or some of the post catalyzed brands.

Poly is indeed used for toughness. But depending on the catalyst and the chemical makeup, the "polys" aren't necessarily on the soft end of the urethanes. Nor are they hard and brittle if properly applied. Go to WoodWeb and snoop around. To make the point that just about any fully cured finish can be "rubbed out", someone took a three coat finish of solvent based polyurethane (Jeff Jewitts product from homesteadfinishing.com) and rubbed it out to such a mirror finish you could read the label on the can in its reflection. No witness lines.

See above.

Only in application. When fully cured, none of these products are toxic.

I think you may have misspoke, or in this case, misstyped. I do it all the time in the wee hours of the morning when I respond.
Shellac and lacquer are >build< finishes. This means that all subsequent coats of the same will 'burn into" or "melt into" the previous coats. This makes them a build finish, meaning you can build a MONOLITHIC coat.
Film finishes are those that rely adhesion to bond to the previous coat of material. These are most lumberyard polyurethanes, varnishes, paints, etc. While they adhere, they do not burn into the previous finish.
There is a good thread that is three or four days old on this very topic on Woodcentral.com with commentary by my favorite finisher/ refinisher, the vaunted Michael Dresdner. If you really want to dig into this subject of "build v. film" pick up some of the books by him and Jeff Jewitt.
The ability to build a finish on a piece of furniture that can be rubbed to mirror finish is one of the reasons that lacquer was the coating of choice for fine furniture makers for decades.
Robert
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