I have just completed a casework project with holly, ebony string and berry inlay. The case is of walnut. I want to keep the inlay, especially the holly, white and not have it turn yellow. I have thought about sealing with shellac sealer, super blonde dewaxed with either wipe on poly or water base. I am concerned that the depth and warmth of the walnut will suffer with water base finish. Does anyone have any recommendations?
TNX
Replies
This is tough because you want things that are challenging to achieve. Finishes that warm walnut will color the holly, and conversely if they keep the holly white will look cold on the walnut. Shellac doesn't change color over time and makes a good sealer. It will be OK over the walnut. Super blonde won't really bring out the best, but it won't do bad things. It would probably be my choice in the end, though personally I like the bit of mellowing of holly that a more amber finish has. But then I am more into antique reproductions than modern designs.
Waterborne acyrlic is clear and many versions will stay clear, though some may do a small color shift toward straw color. Some do impart a "blue" cast that would be awful on walnut.
"Poly" would be about your worst choice since both the resin and the linseed oil which are used in making most all poly's will yellow over time. Alkyd/soya varnishes would be the least darkening, over time and initially, but will still yellow to a greater extent than shellac or acyrlic.
One other possibillity exists, and that would be to use a chemical stain that would react with the tannin in the walnut to darken it while it would have minimal effect on holly without tannin. I have used potassium dicromate for this. Big caveat however, this stuff can be poisonous. You would need to take care in mixing and appying the solution. In addition, if your walnut isn't all from the same tree, it could react a bit differently on different boards. Lots of testing on scrap required.
Padding on shellac is a fine way to proceed. I will say that Zinsser Clear is my least favorite shellac. It has been chemically bleached to remove any of the dye coloring the resin while other grades of shellac contain more or less dye depending on how they have been refined by filtering through activated charcoal, etc. The bleaching process leaves the Clear shellac less moisture resistant than other shellacs. It also contains it's wax, which isn't really a problem unless you wish to apply a polyurethane varnish or any waterborne finish over shellac with wax. Then, it can cause adhesion problems, if not immediately, then down the road. It also is so clear that it may not warm walnut very satisfactorily. Zinsser SealCoat has no wax,and while still quite light, will look better on walnut.
This is the first time that I have tried the Knots part of the website. I am glad you are available. The shellac that is in the can is quite cloudy and was manufactured in 2008. I have heard that there is a shelf life to shellac. Is that true and is the shellac too old? I have also seen shellac amber and the sealcoat. Thanks again for the advice.
Your shellac is probably too old, but to test it, put a quarter sized amount on a piece of glass and see if it hardens completely. I am guessing it won't. As to your project, if you haven't already, now is a great time to make some scraps with the inlay and walnut so you can test out different stains and techniques. I did a much easier project and used striping tape that auto body painters used to tape off either side of the string inlay and sealed and finished it with waterborne lacquer, Once that was fully dry, I taped off the inlay, then dyed the walnut, then sprayed the same finish to the field, then removed the tape, gave the top a light sanding ,then sprayed the whole top with a couple of coats. Again, you need to try it all out on scraps - I did a similar procedure on another project a few years ago and found that the finish coat of waterborne redissolved the dye so I got a cloudy weakened dye on the inlay and had to start all over. If that is happening, either change the finish, or see if a dewaxed shellac will keep that from happening.
I wouldn't use shellac that old on a critical project even though that may be within (barely) the manufacturer's three year freshness warranty period. A process called "esterfication" reduces the ability of the shellac to dry hard. While this can be slowed by the method of processing the liquid shellac, and is affected by the storage conditions of the shellac, it hasn't been eliminated.
The cloudiness is likely to be entirely different issue. It is just the wax suspended in the shellac and is not significant in the final product. It may have an impact on the adhesion of finishing products applied over it, particularly polyuethane varnishes and waterborne finishes.. Shellac with the wax is a bit less water resistant than dewaxed shellac. The wax is not added by the manufacturer but is naturally present in shellac unless removed by processing. .
Actually we should say "refiner" or "processor" rather than "manufacturer" since shellac resin is a natural product secreted by insects and then collected and processed for use. For example, it can be filtered to remove the red dye that gives it color--early in the history of shellac the dye was a major usage. Dye may be removed by filtering, with the most fully filtered shellac being called blonde (or super blonde or ultra blonde.) Dye can also be bleached away with a chlorine bleach, which becomes Clear as marketed by Zinsser, though the trade name for this bleached product is "white". White is only sold as liquid shellac, since the dry bleached shellac resin deteriorates in a matter of days.
Finishing Walnut with Inlay
Chawls,
I have made a couple of walnut pieces with inlay and I will agree with Steve that finishing them can be difficult. You will need to finish a lot of samples and then decide what looks the best to you. I will share a few ideas to try:
- Both lye and lime will color (darken) walnut and may have little impact on your inlay. They are also both much less toxic than potassium dicromate. Test some samples and be sure to apply the clear coat as the color will change dramatically.
- In my experience it is very difficult to seal the inlay sufficiently such that it will not be impacted by a dye or stain. I have tried both shellac and a water based lacquer (Target USL). The latter was more effective but there was still some color change even with two coats applied with an artist's brush just to the inlay. Still, it worked well enough for me on a project with yellowheart and bloodwood inlays that I was able to give it a light stain and fill the pores with a nice, dark pore filler and not muddy the inlay.
- Steve's comment about the different boards ending up different colors is also very important. I have had some success using dye to get everything to the same color but it is tricky with inlays. Again, test on some samples. I would also second Steve's recommendation for Seal Coat over Zissner's super blond.
Good luck and post some pictures when you are done.
Chris
Good point on the general difficulty of getting good results with tape or with a masking finish on the inlay. If the inlay is tight, as it should be, there is almost no way of keeping dye from going under tape, or keeping the masking finish off of the walnut. Frankly, natural walnut still gives a nice contrast with holly without doing flips to darken the walnut even more.
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