Interior panels Part 5 – Selecting and applying a finish

The choice of wood finish is as much a personal decision as choosing the type of wood for the panels.  Many different products are used with great results, and a lot depends on degree of uniqueness desired and the underlying wood.  For me, this stage was the most important (after all, any mistakes made while cutting are usually concealed after the panels are installed).  I spent quite a bit of time researching the best methods to replicate the original appearance and ambiance of Moby’s panels and found myself quickly absorbed in VW panel building threads, wood working forums, face-to-face discussions with woodcrafters, and, well, anybody else that would listen.  Although they promised, many of the VW threads covering this aspect of panel fabrication failed to produce photos of the final results, and I was left to an inordinate amount of experimentation with processes gleaned from research.  I am convinced that I spent way too much time and effort in the end, but I did have quite a bit of fun.

It seems that the original panels did not have a finish at all but rather some sort of photo laminate (which begs the question: Did they really used baltic birch or some other, lesser plywood).  I have yet to verify this hypothesis, which is supported by many respected VW enthusiasts, by sanding down the old panels, but the grain pattern on them does disappear in water damaged and worn sections.  One would think if the pattern came from the wood itself, it would be present regardless of wear and tear.  A photo laminate makes perfect sense when it comes to mass production as it is cheaper, easier, faster, hides blemishes, and prevents both grain pattern and color variation between different pieces of plywood (these differences are easily seen in this series – no two panels I cut had the same overall color or color relationships between light and dark grain).

None of the alternate processes I discovered lend themselves to mass production nor did they replicate the original finish.  I tried brushing, wiping, thinning down paint (both oil and water based), whitewash, various hues and concoctions of wood stains, and multiple coats of everything in trying to match my panels with the originals.  In the end, I simply selected a clear coat finish and let the wood speak for itself, so I will spare everyone the experimental details.  I still like the look of the originals best, but am extremely happy with my results.

Entire panel thread.

I found the original photo laminate (left) impossible to replicate as the lighter grain color in the baltic birch (right) needs to be brightened while the darker grain is simultaneously deepened.  The bare baltic birch is a fairly close match without any modifications and once all was said and done, I decided to simply apply a clear coat finish which would both protect the wood and let the natural patterns and colors show with as little alteration as possible.

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Unless using a covering or perhaps paint, the panels must be well sanded first. This step is critical for a good looking finish and takes a fair amount of time and patience. First, I sanded the panels parallel to grain direction with an electric sander and 80-grit sandpaper in order to remove all the tool marks left from the manufacturing process. A bright light angled over the wood will help highlight any marks remaining after a few passes with the sander. After the 80-grit paper, came 120-grit and then 220-grit sandpaper. Be patient, the time spent on a good sanding will have a huge impact on how the panels look in the end.

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After completing the sanding phase, I used a soft brush and tack cloth to get rid of the dust and clean the wood surface.

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I have seen many types of clear coat products successfully used on bus panels, but not all have the same results. Many, such as varnish, will yellow the wood a few degrees either immediately or over time. Others will darken the wood, and still others will alter wood texture or create a thick layer on top of the wood. While the panels I’ve seen have all been beautiful in there own way, I wanted something that would interfere as little as possible with the natural look of the baltic birch. After having positive results with it on a few doors in the house, I selected the polycrylic clear coat pictured above. This product can be applied in very thin coats, dries relatively quickly, is easy to clean (I used this substance on the kitchen pantry cabinet – let’s just say kids spill stuff), and has a minimal effect on wood color. While available in satin and gloss, I chose the semi-gloss as the best match to the original panels.  Some people swear by oil based products, mostly because they won’t raise wood grain as much, but this water-based stuff seems to do a heck of a job.

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I do not think any product out there won’t have some effect on wood color, but the polycrylic seemed to have the least impact. At first I used a high quality paint brush (cheap brushes are more prone to leave brush marks) to apply a very thin initial coat of finish.  When dry, I sanded the panel (this water-based product will raise the wood grain a bit) with 220-grit sandpaper and an electric sander.  Sanding at this points only takes a few minutes per panel because the goal is not to sand through the clear coat, just smooth the raised grain.  Sanding also has the benefit of helping to check for any tool marks not removed in the first sanding run; just look for the shiny spots not touched by the 220-grit sanding.  If you see tool marks, hit the panel once more with an 80-grit paper. After sanding the first coat, I cleaned the wood with the brush and tack cloth before applying a second, thin coat of finish. This coat was followed by sanding once more with 220-grit paper. If the first coat is not over sanded, the amount of raised grain on the second coat should be significantly reduced. On most panels, a third coat was required before the final application; it mostly depended on when the amount of raised wood grain became insignificant, i.e. the wood surface remaining fairly smooth after applying the latter coats.

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Once I was satisfied, I prepared the panel for the final coat by lightly hand sanding with 400-grit sandpaper. After cleaning the surface, I applied the final coat of polycrylic with a foam applicator (seen in the picture with the polycrylic can). Because I used such thin coats, they dried quickly and marred easily with the paint brush. For some reason the foam applicator did not disturb the drying polycrylic as much. In the above picture, you can compare the finished panel (right) with the unfinished (left). Just a shade of darkening but no yellowing of the wood.

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Close up between finished (right) and unfinished (left).

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A comparison of two finished panels demonstrates the variation of color between different birch sheets. Though not having the consistency of a photo laminate, one would be hard pressed to spot this disparity once the panels are in the bus.

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After the final clear coat dried, I applied a generic water sealer/mildew preventative to the back of each panel in hopes of protecting the wood from any water leaks, spills, or just plain humidity. No sanding required for this!!

The darkened panel is actually a pretty good match for the aged originals.

The completed panel (right) is actually a pretty good match for the aged original (left).  Moby’s interior is a much friendlier, warmer environment in which to awake, but that also may be due to the absence of those pesky speaker holes.

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