Now that I had the woodworking done I could start on the
finishing. Since I was going to use
gloss instrument grade nitrocellulose lacquer for a finish I had two choices
for application. My small air brush and
the larger HVLP setup. With the HVLP gun
I could probably put down a layer of lacquer on the whole drum inside and out
in about 15 seconds or less. What I was
concerned about was the lack of access in spraying the inside. I was afraid that because the finish goes on
so quick I would have a high likelihood of uneven coverage and runs. Also, cleaning the HVLP gun takes way more
thinner and time than the airbrush. In
the end I thought a little extra time in application was a good trade-off for control and ease
of cleanup. However, before I could
start spraying I needed to clean up the sawdust in the shop and build a rig to
hold the drum for spraying. This is what
I ended up with, plenty of space to move around and a couple task lights so I
could see what I was doing.
 |
| Rig for Spraying |
I started with two
coats of vinyl sanding sealer formulated for the lacquer I was using. Process is to spray the inside first off the finishing rig with the shell on edge rotating as I spray. With the
lights set just right I can easily see the wet edge of where I have applied
finish. When the inside is done I hang
the drum in the finishing rig, reset the lights and apply a coat of finish to
the outside.
 |
| Shell with 1 Coat of Sanding Sealer |
With both sealer coats applied and wet sanded to remove any
dust nibs or other debris that may have gotten into the finish I was ready to
start applying the gloss lacquer.
 |
| Shell Ready for Gloss Lacquer |
After 4 coats of gloss lacquer the finish has good build
some depth and a good gloss. I have one
more build coat then a flash coat that is 20% lacquer and 80% thinner. You can see the airbrush below the shell in the lower left background.
 |
| Shell with 4 Build Coats |
While I was spraying the last build coat on the interior
about 2” from being done I noticed some drops on the surface I had yet to
spray. Thinking they were some stray
water drops I had missed from when I wet sanded I wiped them off. Much to my surprise and chagrin they were
lacquer and wiping them off had created a major problem with the finish. The solvent in the drops had softened nearly
all the previous coats I had so carefully applied and when I wiped them up off
came 3 of the 6 coats of finish. Later I
found that what had happened was a gasket on the airbrush had broken which allowed
a small leak that dripped those half a dozen drops across the surface. I was so honked off I tried to fix the
problem right away and of course only made it worse. Now I had pits in the finish like craters in
the moon, well it seemed that way to me.
In reality they were all confined to about an inch square and were only
a few thousands of an inch deep. That
said, I was highly teed off. At this
point the best thing to do is quit for a while, so I did. The next day when the finish had cured some I
cleaned up the area with a hand scraper then used a pipette to add about 6
layers of finish to the divots bringing them a little proud of the surrounding
surface.
 |
| Finish Repair in Progress |
 |
| Completed Finish Repair |
With the repair done I continued on and gave the outside and
inside the final flash coat. The flash
coat is a lacquer/thinner mix using much more thinner than normal. The mix is about 80% thinner and 20%
lacquer. Checking the next day there
were a few of the inevitable dust nibs in the surface. Rather than try and get them out now I
decided to wait and let the lacquer harden for 5 days before I did anything.
After waiting for the lacquer to cure I started the finishing
the finish process by using 12,000 grit wet sand paper to very gently rub out
the few dust nibs. The next step is to
mount a buffing wheel on the lathe and using a very fine polish work the
surface until it is just glass smooth.
Last step is to change the wheel and use it to apply Carnauba wax.
 |
| Buffing Wheel on Lathe |
One thing that I learned some time ago when I first started
doing the buffing process is that a piece of dry lacquered wood held against a
rapidly rotating cloth wheel in a dry climate produces a whole LOT of static
electricity. Can you say Van de Graaff
generator? Nothing like getting blasted
by a good sized static electrical charge every 10 seconds. To keep this from happening I found the
easiest way to keep the charge from building up was to ground myself. Pretty simple in the summer, use the buffing
wheels barefooted. However, in December
it’s a little too cool for that so just keeping some bare skin against an
unpainted surface on the lathe does the trick. Not high-tech but effective.
With the shell done I signed the piece and got all the
hardware out ready for final assembly.
 |
| All the Drum Parts Ready For Assembly |
Putting all the pieces on took maybe 45 minutes and when
done here was the result. I did not
go through the tuning and head setup process but just tightened down the heads
finger tight plus half a turn. Even then it sounded pretty good to me. Final conditioning of the heads, setup and
tuning will be done by the client to suit his style and needs.
 |
| Completed Drum |
My total time on this project was about 10 hours for design,
63 hours for woodworking and another 12 hours for finishing. Not included are any of the teleconferencing
discussions with the client. This has been a great project; a bit
different, challenging, learning something I did not know a lot about and
ending up with a piece I was really happy with.
 |
| Leopardwood Scrap |
As to what’s next, there are two things. First, I have a leftover scrap cutoff from one of the
Leopardwood blanks that is just the right length to use in making the body for
a fountain pen so I think I will do that.
Second, I saw an article in Fine Woodworking on Oval Shaker Boxes that
looks interesting….
Next Up – Segment Cutoff & Pen
No comments:
Post a Comment