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Thread: Issues using dye and grainfillers with shellac for cerused look...

  1. #1

    Issues using dye and grainfillers with shellac for cerused look...

    I have a finishing problem that I am trying to solve. I've done a lot of woodworking but not a lot of finishing so I've been experimenting with various methods and documenting my progress as I learn.

    While playing with some liming wax on Oak that has been dyed black, I came across a look that I would very much like to use on a computer desktop that I am building. Everything I’ve done so far is on test boards since I only have one shot at the finished desk, which will be 1-1/2” Red Oak with some very nice grain patterns. My end goal is pitch-black wood, with extremely high-contrast white grain with very sharp edges—that is, not “soft edged grain” from the white grain filler and black dye blending slightly.
    I’ve looked at many techniques & recipes (some on this site) for this “ceruse” look but none involved dyeing the wood as black as what I’m attempting.

    My recipe was as follows:

    -After sanding, wetting, drying, sanding to 150 grit to raise the grain. I then brass-brushed the grain and blew it out.

    -I applied two coats of Behlen Solar-Lux Black dye 1 hour apart. This is an Alcohol-based dye. I then waited a couple of days to insure evaporation of the dye carrier.

    -Three sprayed coats of lightly applied dewaxed Shellac, 1 hour apart, as a sealcoat over the dye. Let dry two days.

    -At this point I tried filling the grain. I’ve tried several things, among them:

    -drywall compounds. This works, and cleans up easily with a light sanding with scotch pads.

    -Aquacoat Grain filler (clear) with white Mixol tint added. Seems to soften the dye in the grain and pull some of it into the grain filler.

    -Briwax white liming wax. This gives the highest contrast, stark white grain I’ve seen and didn’t reactivate or leech the dye. The manufacturers of this liming wax claimed to me (on a phone call) that there really is no wax in the product and that you can sealcoat/topcoat over it.

    -Timbermate Grain Filler with a little Mixol white tint. Gives a good white grain but is a little difficult to clean off the surface of the shellacked/non-grain flat surfaces. Didn’t reactivate or leech the dye in the grain.
    I suspect that the Sprayed shellac sealcoat, which landing on the flat of the wood, is not making it into the actual grain grooves themselves (perhaps the droplets/surface tension are larger than the width of the grain) and that is why some of the grain fillers are leeching dye and not being shielded by the sealcoat?

    -Now I lightly spray a few more coats of dewaxed shellac over everything in anticipation of a topcoat of three coats of General Finishes water-based High-Performance Satin. I’ve used barely dusting coats, because the Shellac seems to reactivate the dye and cause it to smear into the grain fillers in all cases. The Briwax held up the best.

    I am now considering skipping the Shellac final seal and top coating and instead using a pourable epoxy over the grain filler without a barrier coat, but I’m not keen on the 1/8” thick glass-like sheen that epoxy brings to the party, even though it would have a more durable desktop surface. I'm also concerned about the epoxy bonding correctly over the already shellacked dye.

    I’d love to hear any comments or suggestions anyone may have for preventing reactivation of the dye (or anything else I may have missed).

  2. #2
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    See if you can locate some Titanium Dioxide to incorporate somewhere in that finishing schedule. It is about the whitest material I can think of. I retired from a confectionery factory where it was used in a syrup to lay down a base coat under some transparent dyes. Since it is a dry, ultra-fine powder, I would think it could be mixed into shellac easily.

  3. #3
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    Don't know all the answers, but you can bet that applying shellac to the alcohol based dye has caused leaching of the dye into the shellac. Thus, the shellac isn't shielding dye from filler. A light coat of varnish (thinned significantly) over the dye would keep it from leaching. I'd test before! Although it is soluble in alcohol, the primary solvent in Solar Lux is acetone, with alcohol and water each being less than 10%.

    One good blackening agent is waterproof India Ink. (Some is shellac based and would be lifted by shellac.)

    I like oil based pore filler in general. Por-O-Pak is common but shrinks, though not as much as most waterborne porefillers. Old Masters makes a good one, and perhaps the best is the Sherwin Williams grain filler, but only available in gallons.

  4. #4
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    Sam, first thing to address is surface preparation. You want a sharply defined appearance so you need a sharply prepared surface. How good are you with a hand plane because you need to use one to cut a smooth surface. Sanding feathers and fluffs the edges of the pores which you don't want. Address this first otherwise you will continue to have problems.

    Your filler needs to be as inert and dense as possible. This means a one-pot polyurethane type filler as first choice. The ones Steve mentions are a good start.

    If you are going to finish with a waterborne product, why are you using so much shellac? Just stain it, give it 2 light coats of the waterborne you are using with a light sand in between, fill the grain and finish coating. Cheers
    Every construction obeys the laws of physics. Whether we like or understand the result is of no interest to the universe.

  5. #5
    Thanks for the tip, Bob, but mixing with the shellac is exactly what I'm trying to avoid. Thanks, though, might make a good alternative to the Mixol tints if I run out!

  6. #6
    Hi Wayne,
    I did some light planing and a little scraping with newly sharpened tooling before the sanding, so I'm pretty certain I have nice sharp edges along the top of the surface, plus the fact that the BriWax gave such a sharply defines edge tells me that the "geometry" of the grain edges are hard. The chemistry is what seems to be my biggest problem.

    To answer your question as to why I am using so much shellac when I'm planning to finish with a waterborne product: the reason is that the waterborne topcoat does the same exact thing as the shellac--that is, it re-activates the dye, which then bleeds/leeches into the white grain filler. I tried that as an experiment and got the same nasty result. The Shellac was purely to act as a barrier coat, but had the same undesirable effect. Lack of a proper barrier shield between the dye and topcoats that doesn't pull the dye seems to be the primary issue with my existing recipe.

  7. #7
    Steve,
    If I understand what you are suggesting, basically I should try a varnish as my seal coat after dying, and again I assume, after grainfilling and before topcoating. I've never used varnish before so I'll have to give it a try, thanks.

  8. #8
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    FWIW, I've never had a problem with alcohol based dye bleeding when spraying shellac on top. As long as the first coat is light it works just fine. I do this all the time when I plan to use a WB topcoat, and the advantage over using the WB topcoat as the sealer instead is that the shellac prevents grain raising which can be a huge issue with WB topcoats, especially on oak.

    John

  9. #9
    Thanks for replying, John.
    I suppose the bleeding may not be noticable if all you are doing is spraying shellac onto the dyed wood, as it may not "draw" the dye up to the top of the newly added Shellac. My issue seems to involve the Shellac softening the dye, and "smearing" it around with the grainfiller *under* the surface of the shellac itself. But it is good to know that it isn't making the surface of the Shellac "dirty" where you could get dye on anything sitting on top of it.

  10. #10
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    Sam, you are still filling the grain too soon. As I said above, stain, seal, grain fill, finish in that order. You need to isolate the dye and the filler and this will do it. Cheers

  11. #11
    Sam, did you resolve your issues? If so, could you tell us what you did?

    If not, I can give some additional information that might be useful. I am trying to do exactly what you describe: create a white pore filling on very black oak. My process does not show the bleeding that you describe, though it has another issue - some of the white fill gets left in the white pores between the cathedral shapes, leaving a ghosting effect that I don't like.

    My recipe:
    - sand red oak to 220
    - raise the grain and sand again
    - wirebrush
    - apply General Finishes Water-based Black Dye Stain and wipe off excess
    - after at least 2 hours apply Black Dye Stain again
    - apply Zinsser SealCoat thinned 50% with denatured alcohol by brush
    - after 2 hours apply another coat of thinned SealCoat
    - brush on Benjamin Moore Acrylic Glaze into which the store mixed in white paint. wipe off excess
    - repeat glaze after a couple of hours
    - brush on 2 more coats of thinned SealCoat
    - spray 3 coats of General Finishes High Performance Water based top coat

    As I say, the white filling does not get bleeding from the dye; the dye seems not to be dissolved by the Sealcoat and the oak remains deep black, just what I want. My issue is that I can't remove the white glaze from the small shallow pores without also pulling out a substantial amount of white from the deep pores that I want filled. I have tried using a T-shirt, a putty knife, and a white Scotch Brite pad for removing the excess glaze and none of these do what I want. I want high contrast between the deep black of the oak and the white in the pores without ghosting.

    Another note: the glaze dries very fast, which will make it difficult to work with for a large piece. The guy at the paint store said I can add an extender to it but I haven't tried that yet.

  12. #12
    Hello Tom, thanks for replying.

    No, I have not found a solution with which I am happy. I have tried just about everything suggested. I have been extremely picky as to keeping the "sharpness of line" between the white grain and the black non-grain, and everything I have tried "dulls" that edge or bleeds slightly over the white grain, ruining the look I can only get without putting anything over the grainfiller.

    I have even tried using an oil-based stain instead of dyes, and per the manufacturer's suggestions have let it cure for 3 weeks before grainfilling and sealing. It still bleeds onto the white GF once a sealcoat is applied.

    This has turned into quite the chemistry experiment. Ghosting is a good word for it as you said. As you mentioned, wiping is a whole trade-off of getting off the excess GF (squeegees, towels, cotton sock, paper towel, scoth brite, etc) without taking off the Black or getting black dust into the white grain itself.

    Using sandpaper on a fine, HARD block might help you with the shallower grain. I found that the softer the removal medium was, the easier it was for me to 'push' it into the shallow grain and cause the removal you've experienced. The harder the block and the smaller the grit, the less likely it was to "sink below the surface of the wood".

    I may have to give your Acrylic Glaze a try. My end piece is a large L-shaped desktop, 72"x48", so I'm determined to nail this mix down before I commit the recipe. I will definitely repost here once I find something that checks all my boxes.

  13. #13
    Thanks for the info. It may be that, to remove the "ghosting", there need to be multiple applications and removal of the filler, with sufficient dry time between applications. That will be one of my next experiments. Also, I've ordered some "Romabio Limewash", which is essentially old-fashioned whitewash, which I'm hoping will be easier to manipulate. However, I don't know if any of this addresses the dulling effect that you're seeing.

  14. #14
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    Quote Originally Posted by John TenEyck View Post
    FWIW, I've never had a problem with alcohol based dye bleeding when spraying shellac on top. As long as the first coat is light it works just fine. I do this all the time when I plan to use a WB topcoat, and the advantage over using the WB topcoat as the sealer instead is that the shellac prevents grain raising which can be a huge issue with WB topcoats, especially on oak.

    John

    This sounds right to me. What cut of shellac are you using? I normally use 1 pound cut of super blonde but that may not be right here, it puts a lot of alcohol (solvent) onto your die. A 3 pound cut or more will apply a seal coat with less alcohol.

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