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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 Iíve done so far is on test boards since I only have one shot at the finished desk, which will be 1-1/2Ē Red Oak with some very nice grain patterns. My end goal is pitch-black wood, with extremely high-contrast white grain with very sharp edgesóthat is, not ďsoft edged grainĒ from the white grain filler and black dye blending slightly.
    Iíve looked at many techniques & recipes (some on this site) for this ďceruseĒ look but none involved dyeing the wood as black as what Iím 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. Iíve 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 Iíve seen and didnít 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. Didnít 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. Iíve 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 Iím not keen on the 1/8Ē 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.

    Iíd 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
    Join Date
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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

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