Writing Desk Finishing – Color and Craqueleur

With the desk surfaces well-sealed with lemon shellac and the finish foundation built up with garnet shellac it was time to wrap up the color work while simultaneously imparting the craqueleur that would reside under the final, polished surface imparting the “look” of an ancient but well-cared-for surface.  The process was simple, one that I have employed before and takes advantage of the properties of the materials found on the shelves of finishing shops.  Well, at least on the shelves of my finishing shop.

As I have written previously I am loathe to contaminate the raw wood with colorant that cannot be easily removed.  Hence my distaste for pigmented “stains,” dyes, or chemical treatments.  I find these techniques to be insufficiently control-able for precision finishing, preferring instead to introduce any coloration into the finish system itself.  Not only is this much more easily controlled but comparatively effortless to undo if the target is missed.

My common terms for this kind of in-finish coloration is “toning” if the coloration is included in the film forming material itself (i.e. the varnish), or “glazing” if the coloration is imparted via a discrete material in-between coats of finish.  In this project I was able to blur the lines in these concepts and add an additional feature to arrive precisely where I wanted to go.

In short, my goal was to provide visual unity of both the color/tone and impart richness to the texture to replicate a finish that gave the appearance of being well-cared-for but 200 years old.  It was not to be a grain filled, brilliantly glistening “French” polished surface, that was simply not appropriate for this project.  I wanted the surface texture to be presented subtly for both the wood grain and the cobwebbed craqueleur within the finish film itself.

Here is a brief recitation of the technique I used to accomplish this.  It depended on understanding the nature of materials and their means of forming films (or not).  There was no magic elixir, but rather an exploitation of those materials.

I began with my glaze formulation, which first consisted of solid acrylic resin beads dissolved in hot mineral spirits to a 25% solids content.  This served as the backbone for the glazing solution and the governor for my desired solvation limits that in turn controlled the craqueleur.

To this I added some oil/resin varnish in the proportion of 1 part acrylic resin solution to 3 parts of varnish, followed by stirring in asphalt as the primary chocolate-y brown colorant and a dab of sienna artists’ oil paint to get the right amount of reddishness, thinned as needed with naphtha.

I slathered this on to the surfaces that had been well-built-up with the shellac base.  The glaze was evenly distributed with a well-worn vintage (and thus soft-ish) bristle brush, pulling off glaze in places where it was imparting too much unnecessary coloration, smoothing it out where the color was correct.

The final step was to soften any striations by whisking the surface with a badger blender or goat hair hak-e brush just before the glaze dried too much to be manipulated further.  The entire process for a particular work area from slather to done was probably about 90 seconds.  This was then allowed to dry overnight.

The next morning to lock it all in place I spritzed it with a light coating of sprayed shellac.  This resulting surface might have sent an inexperienced finisher screaming for the hills but I had a huge smile on my face because the result was exactly what I wanted to achieve.

Let me explain.

The oil-resin varnish and artists’ paint in the glaze had stiffened but were not yet fully hardened, so the introduction of of a more polar solvent (in this case alcohol in the sprayed shellac) to the glaze would cause the glaze film to become imbibed with the solvent, swelling the polymer matrix into a crinkled texture.  On the other hand, since the acrylic resin and asphalt are not susceptible to the same solvation effect they remained calm, otherwise the surface would not have been a variegated craqueleur, it would have been velour.  And, with the glaze film being ultra thin yet bonded to the underlying shellac via the adhesive properties of the acrylic resin component I did not have to worry about the whole laminar construct coming apart.

(NB – I discuss all these properties and effects much more thoroughly in my upcoming book, A Period Finisher’s Manual).

I waited another day to make sure the solvent from the shellac mist coat had diminished sufficiently and abraded the surface very lightly before building more finish.  At this point my main concern was adding too much additional alcohol to the system and causing even more oil/resin film swelling, so rather than brushing on shellac to build the finish I padded it on.  Remember, my goal was not a glistening pad-polished presentation surface.  I padded the finish simply because it was the best way for me to deposit film-forming material while controlling the solvent encroachment.

After enough new finish was added on top of the craqueleur, three applications as I recall, I abraded the entire surface smooth, in essence leaving the craqueleur embedded down in the finish but still presenting a smooth surface that I could polish out.  I built up another half dozen padded applications to the writing surface after the piece was assembled then set it aside for a fortnight before final polishing, assembly and detailing.  As you might surmise the craqueleur was so subtle it was impossible for me to photograph.  It has to be observed in real time and in real space.

It is worth remembering the beginning point for all this color work.

Now it was time for the polishing, assembly and detailing.

Stay tuned.