>Hi, I have just begun experimenting with dewaxed amber Shellac and am using it as a thin coat (1 lb cut, mixed from flakes) over water based dye before I glaze. I have been experimenting on oak and when it dries, there are always lots and lots of tiny crystal bits in the grain, espcially in cathedral grain. Elsewhere, the shellac dries flat and without the crystals. You can see them and feel them. They sand out okay but not perfectly. Is this normal? Can it be avoided? I suppose they would disolve with a new coat of shellac, but my intention is for the next coat to be a glaze, not more shellac. Thanks! Sanford
I have done the same procedure you are describing a number of times, using Jeff Jewitt's Transtint dye, and using both Jewitt's and Liberon's shellac flakes. At a light cut, as you describe. And using ordinary Borg denatured alcohol.
I haven't experienced the crystal effect, but here's a thought. The water-based dye is raising the grain, and you're probably sanding it back before applying the shellac. Do you suppose some sanding grit is getting caught in the cathedrals, and staying behind?
>I did vacuum the wood but maybe did not get all the dust? I did not put the shellac through a coffee filter but I did put it through something I bought from a woodworking store some time ago specifically to filter shellac. It is a paper cone with a fine mesh bottom. I wonder if it is not filtering well enough. Does the coffee filter really make a difference? I tried using one and if filters literally one drop at a time. Sanford
>I wonder if what you are seeing is the shellac setting up the wood fibers like a sealer does. If so, it's perfectly normal and you just lightly scuff sand the fibers off.
On the other hand, even a fine mesh paint filter should let a one or two pound cut of shellac flow through very freely. Coffee filter is awfully slow - never worked for me, and you don't need that fine a filter.
Maybe this'll work. Take a piece of your oak scrap, and plane it smooth (no dye, no nothing), and apply shellac. Look for crystals. If none there, then it's the wood prep, not the shellac.
Now if there are still crystals on the test piece, I think I'd still repeat the test on some other piece of smooth wood (like maple or walnut) and check results before doing a lot of shellac research. Maybe there is something about the oak.
I've never filtered the shellac flakes I've made up, and that may not be the best practice, but I've not had problems.
>I've seen such "crystals" in oak pores also. I think what is happening is that the shallac does not penetrate the large pore completely but is left as a small droplet on the edge. As the alcohol evaporates, the shellac shrinks and is left as a small bit of finish. The bits disappear with subsequent coats. Perhaps a thinner first coat would do better.
>Hi Sam. I assume you mean wipe rather than brush? I think I will try a few experiments trying everything suggested till I isolate the cause. One other thing I discovered is that those crystals do not go away easily! I tried wiping down the coat of shellac with alcohol and the shellac itself disolved, but the crystals remained. I flooded the surface with alcohol and rubbed and some came out, but a most did not. I planed off the old finish with a hand plane, and most came out, but there are now a few little black specks here and there in the grain. Not enough to hurt anything, but rather odd. I am leaning toward thinking I did not get the dust out of the grain well enough. Thanks for all the suggestions. Sanford
>Sanford, if you are using white oak the crystals may be tyloses. Look at a scrap of your wood under some magnification and before any finish is applied to see if the crystals are present.
>Well, I am not sure I figured it out. I redid a number of pieces of scrap. I removed the old finish with a plane and started over. (On some pieces, the crystals were very deep in the grain and I had to take off a fair amount of wood.) And surprise, some pieces came out perfectly and some still had those crystals. So far, my best guess is dust contamination. I am very careful to clean wood before putting anything like varnish or stain etc. on, that is, anything with a binder. But I may not have cleaned the wood fully before using the dye on the troublesome pieces. I never used dye before. It is just waterbased transtint, or whatever it is called. Maybe it trapped some dust inside the grain? I wet the wood before dying and sanded and cleaned the wood, but maybe I did not do it well enough. Maybe I left some fuzz dust in the grain of some pieces. Hm . . . maybe there is a reason I always used Watcos in the past! Now that I think of it, it looks pretty good on oak. Sanford
