Sealing Over Water-Soluble Aniline Dyes

      Bleeding between products makes getting that "piano" finish tricky, but it can be done. March 18, 2005

Question
Though having been a woodworker for 30+ years, I do not consider myself a finisher. I have a handful of simple finishes that I’m comfortable with and that seem to please my customers. Within the past couple of years, I discovered the wonderful world of aniline dyes. I had some work in Baltic birch plywood that required really vibrant, but transparent, colors. The water soluble aniline dyes from Woodworker’s Supply seemed to fill the bill. Used ‘em, loved ‘em. I sealed the pieces with Benjamin Moore’s Stays Clear acrylic polyurethane. Both the dye and the polyurethane were sprayed. Four coats of poly with sanding between coats yielded an attractive finish. In all honesty, using the Benjamin Moore Stays Clear was not my first choice as a sealer. I am a fan of Deft clear wood finish brushing lacquer. I had enough of the Benjamin Moore product leftover from a previous job. And the customers for this job are environmentally/health conscious folks, as should we all be, and were happy to hear of my choice of finish.

Now fast forward to this past summer. I was contracted to build a mahogany china cabinet. I made some border inlay of ebony and magnolia to use around the perimeter of the doors/drawers.

I used an oil-based paste wood filler on the mahogany, applied in the traditional manner, rubbed in by hand, then removed it across the grain with burlap. I allowed a 24 hour dry, according to the manufacturer’s instructions. I then sprayed the water based aniline dye, a dark red mahogany J. E. Moser brand. Again per manufacturer's instructions, allowed 24 hour dry.

I had sealed the inlay with a bond shellac, 2 coats before applying the paste wood filler and before spraying the aniline dye. The shellac still absorbed some of the dye, making it necessary to scrape the shellac off the inlay – what a pain!

Here’s where the story turns ugly. I then sprayed the first coat of Deft clear wood finish. I used the material just as it comes out of the can – no thinning, no additives. The finish never dried hard, rather gummy, even after a 72 hour wait. After lightly sanding everything as well as I could, I ultimately covered my sin by sealing the entire mess with, you guessed it, Benjamin Moore’s Stays Clear. Needless to say, I lost my keister on that job.

This past October, the same customer wanted a companion piece (can you believe it?). This time I eliminated the paste wood filler, though I wanted to use it in the worst way. I was just too gun shy after the previous fiasco to run the risk of more trouble caused by filler. I understand there are water based paste wood fillers now, but I really couldn’t afford to experiment with this job. This time around with the inlay, I used blue masking tape burnished at the edges with a spoon-end modeler. I then sprayed the pieces with the water soluble aniline dye and allowed the 24 hour dry as per manufacturer instructions. I then sprayed the piece(s) with 3 coats of Benjamin Moore Stays Clear upon removing the masking tape. I had a little bleed in a few places. I used Clorox applied with a Q-tip to remove it the best I could, but spraying with subsequent coats of Benjamin Moore actually seemed to cause it to renew itself. Subsequent retreatments with Clorox rendered it presentable, but I’m not proud of it. Also, subsequent coats of Stays Clear appeared slightly duller in the areas I Cloroxed than in surrounding areas.

Is there a system by which I can achieve that piano finish on mahogany with paste wood fillers and my beloved water based aniline dye, and finally apply a high-gloss protective clear sealer, all of which are compatible? Does anyone have any foolproof method(s) for masking inlays? Anyone who’s ever used water soluble aniline dyes knows they are in fact water-thin and therefore can find their way into anything!

Forum Responses
(Finishing Forum)
From contributor J:
No need to be gun shy. Now you know why finishers twitch:>) First off, I feel your finish schedule can be modified: samples, samples, samples done beforehand. For them - A. Apply spray water dye to wood first, let dry and light sand to remove raised grain. B. Not too light, not too heavy. Apply a wash coat of your finish to protect dye, but keeping in mind not closing pores or grain for filler. C. 220/320 light sand wash coat. D. Apply filler (safe bet is to allow longer dry time in colder or humid areas. (a) Use finish to fill pores if inlay is a concern. The use of fuming or chemical dyes help in light color woods not darkening as much as tannin (darker woods). If possible, can you fill prior to inlaying without getting material in inlay areas for glue and wood?



From the original questioner:
Thanks for your suggestion. I really like the schedule you suggest - makes sense to me. I have a project coming up that will allow me to try your way. Have you any opinion about the Benjamin Moore Stays Clear, or is there some other water based clear finish you suggest? I really like the lack of fumes/odor offered by the water based stuff.


From contributor J:
There's a water clear water based wood filler by Chrystallac which you can see at Homestead Finishing.com. I'd use the Target water based shellac for a sealer coat and then a Target topcoat (they have a selection that looks great as far as their capabilities are concerned). I have not used this product yet, but I've heard good things about them. I especially want to try the Oxford brand from Target. I almost forgot that Famowood makes a w-b filler that supposedly works really well. Let me know.


From the original questioner:
Thanks for the info on the Chrystallac, Target products, and Famowood w-b filler. I recently had a similar project as the one that gave me such fits as the one last summer, but had much better results. Just wanted to share to anyone who might benefit from it. I had a zebrawood inlay sandwiched between two 1/32" ebony strips, with the balance on the piece on either side of the inlay being African mahogany. Due to the relatively small amount of mahogany, I opted to not mess with any wood filler, planning to instead simply fill the pores with several coats of acrylic polyurethane, sanding between coats, which, by the way, worked beautifully - got a really nice piano finish. Anyway, I first coated the zebrawood inlay with two brushed-on coats of Deft brushing lacquer. I used it because I had it on hand (best reason of all, no!?), and because it dries quickly. After drying thoroughly, I masked the z-wood to the midline of both ebony strips. I used the low-tack blue masking tape slit to an appropriate width for the inlay. I then sprayed the rest of the piece, the mahogany, with the water soluble aniline dye. Had no bleed onto the z-wood whatsoever! After 24 hour dry, sprayed two coats of the BM Stays Clear - again, I had it on hand - onto the project and let it dry thoroughly before removing the masking tape and gently sanding the edge of the acrylic p.u. to blend into the overlay. Then proceeded to apply several coats of acrylic p.u. to the entire piece. Really got super-nice results. Couldn't be happier. I'm certainly not suggesting it's the best way to go, but it really worked well for me.


From contributor B:
Contributor J has the right idea: stain, then seal or washcoat before trying the grain filler. I never had any luck with oil-based grain fillers; they all seemed to shrink or wipe out of the pores no matter what I tried. I have had good results with a washcoat of thinned Oxford water reduced shellac sealer (yup, it's water based shellac) before applying water soluble aniline dye. Washcoats are meant to eliminate the blotching from glue starting to bleed up through sapele pommele veneer (that's a whole other topic), but it also works for curly cherry. The dye then goes in very evenly by brushing on and wiping off (although it's much lighter than dye on raw wood). I sealed with full strength Oxford WB shellac before using Target's water based grain filler (much less of a mess than Pore-O-Pac). Water soluble aniline dye powder can be mixed directly into Oxford USL for a toner for more color (1/8 teaspoon in a quart) followed by Oxford USL topcoats. Final sanding 600, 800, 1000, 1200, buff with automotive buffing compounds, and you get a mirror finish.

Masking off inlays and string-banding is a whole other problem, and I'd appreciate if you'd share your solution when you happen upon it. Shellac masking full strength seems to work for the Constantine's sunburst veneer inlays, but it did not help for the maple string banding. Next time I'm going to try the plastic tape that auto body finishers use (I believe it's called Fine Line), which looks like electrical tape with a more friendly adhesive. Also, the next time I use string banding it will be white or ivory plastic so it won't absorb stain (Constantine's has the strips, they're also available at hobby shops and are sold in different colors for guitar binding through luthier's catalogs (like Stewart MacDonalds). The stain will bleed less if there's a washcoat, and a toner doesn't bleed much if there's a sealer underneath the tape, but it's not perfect.



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