Beginning the Varnishing Sequence

Final Varnish Preparation

Wet down the wood,to raise the grain and accentuate “problem” areas

I wetted the whole bass down with coffee, mainly to raise the grain a bit, but partly to add a little color to the white wood of the Sitka spruce belly. The Oregon Big Leaf Maple is already pretty colorful.

Back plate of five-string double bass, wetted with coffee.
Back plate, wetted with coffee.

 

Then I turned the lights off in the workshop and went over the whole bass, inch by inch, with a small flashlight, held at a low angle, to make shadows wherever there was a discontinuity in the surface. As I located them, I scraped or sanded away the problems, before moving on. It took quite a while, but I was pretty happy with the outcome.

Mineral Ground

The next step is to coat the wood with a mineral ground: a suspension of extremely fine particles of gypsum in water is what I use. I brush it on, one section at a time, rub it in vigorously, to get the tiny particles into the pores of the wood; then rub off any excess, with a rag. It always looks as though I took all of it back off, until it dries.

Mineral ground in progress; sides nearly dry; back only begun.
Mineral ground in progress; sides nearly dry; back only begun.

 

Mineral ground continuing: Back is 2/3 complete: beginning to dry.,
Mineral ground continuing: Back is 2/3 complete, and beginning to dry.,

 

Mineral ground complete on back and sides of bass. Drying rapidly.
Mineral ground complete on back and sides of bass. Drying rapidly.

 

After the ground is fully dry, I sand all over with fine abrasive, to remove any dry patches of excess mineral. There will be very small discontinuities that have been filled by the mineral ground: this is desirable, and I am not trying to remove those places.

When the ground dries, the bass will be stark white, but when I apply the sealer, to lock the mineral particles in place, the mineral ground becomes completely transparent, permanently. It will never be visible again.

So, here is the bass, with the gypsum fully dry, mounted in my varnishing fixture, and ready for the sealer:

Five-string double bass ready for sealer.
Ready for sealer.

Sealer

I am currently using rosin dissolved in turpentine and alcohol as a sealer. The liquid (alcohol first, then turpentine) evaporates, leaving the rosin in the pores of the wood. When dry, this helps prevent the varnish from soaking into the wood, so as to minimize the sound-dampening effect of excessive varnish penetration.

This is the part of finishing I like best: it seems almost magical to see the stark white of the mineral ground disappear instantly and permanently as the sealer permeates the gypsum and renders it transparent, so that the beauty of the wood is revealed.

Sealing the front plate of a five-string double bass.
I begin by sealing the front plate.

 

Sealing the ribs of a 5-string double bass.
Then I rotate the bass in the fixture and seal the ribs.

 

Sealing the back plate of a five-string double bass.
Then I work on the back plate, and continue…

 

Front view of fully sealed 5-string double bass.
Until the whole thing is done! Here is the front view.

 

Back view of fully sealed 5-string double bass.
And here is the back!

 

After the sealer is dry, or just before it is completely dry, I rub down the surface of the wood with alcohol, to pick up any rosin that may have remained on the surface. When the sealer is fully dry, I go over the whole surface, lightly, with fine sandpaper, to pick off any bits of wood fiber that may have raised during the ground and sealer process.

Varnish plan

I always begin with a yellow varnish: I like the way it shines through the darker pigmented varnish when all the finishing is complete. In this particular case the maple was dark enough that even the yellow varnish will end up looking pretty dark. So, though I will still begin with the yellow, I will have to add a good deal of darker varnish on the front, to balance the color with that of the back. This is just a type of “Judgment call” that the maker must always consider when finishing an instrument. As I add coats of varnish, I will pay attention to which areas need darker varnish, and which could use yellow or clear varnish.

 

But Varnishing will be in the next post!

 

Thanks for looking.

Closing the Corpus

Time to close things up!

First things first:

The last time I posted, I had temporarily installed the neck, and (I thought) I had glued the neck heel root in place, as it was to be a permanent part of the corpus, glued to both the neck mortise and the back button.

So the bass looked like this:

Bass with temporary neck set.
Bass with temporary neck set.

 

Side view, showing neck heel break-away joint.
Side view, showing neck heel break-away joint.

 

The heel root looked like this:

Heel root positioned and glued to mortise, using hide glue.
Heel root positioned and glued to mortise, using hide glue, with paper break-away joint.

 

I was so confident that everything was right, that I even sawed off the excess heel root, visible in the above photo, and planed it flush with the back of the neck block, in preparation for installing the back plate.  But!  When I broke the paper “break-away joint” (see the above photo) the heel root gently let go of the mortise and was completely loose. (Rats!)

It turns out that hide glue doesn’t stick to carbon fiber plate! Ok… so I had to start over, and this time glue it home with epoxy. I put a plastic bag around the neck heel to protect it, coated the heel root with epoxy on the bottom and two sides, and slid it all back into place, this time bolting the neck in solidly, and clamping the heel root tightly against it. It all worked this time.

Beginning the purfling of the back plate

While the epoxy was curing, I decided it would be a good idea to at least install the “purfling weave” portion of the back plate purfling, before installing the plate. I figured it would be easier while the plate was still loose. The reason I wait until the back plate is installed to do the rest of the purfling, is that the corpus often changes shape a little when the mold is removed, so I can’t guarantee that the overhang will still be the same. If I have already installed the purfling, then I am stuck: but if I have not, then I can maneuver the overhang to being as close as possible to what I wanted, and install the plate, then plane away excess all around until the overhang looks right again, and finally put in the purfling so that it looks as though everything just worked out right, to begin with.

Cutting the slot for the purfling weave on the back plate for five-string double bass .
Cutting the slots for the lower purfling weave on the back plate.

 

This is a weave that I came up with for my very first five-string fiddle and which I have tried to incorporate on all my subsequent five-string instruments. It is just a modified “fleur-de-lis”…nothing really special, but I like it. I use the same design, upside down, in the upper end.

Picking the waste wood from the upper purfling weave.
Picking the waste wood from the upper purfling weave.

 

Upper weave slot nearly complete.
Upper weave slot nearly complete.

 

After cleaning the slots out, I used heat and water to bend the purfling strips to fit the curves of the weaves, and glued them in using hot hide glue.

Both purfling weaves completed on the five-string double bass back plate.
Both purfling weaves completed on the Oregon Big Leaf Maple back plate.

 

I planed the weaves flush with the plate after they were dry, using a gouge, a small finger-plane, and a scraper.  You can see the beginning of the rest of the purfling slots, how they will connect to the weaves.

Purfling weave planed flush.
Purfling weave planed flush.

 

Closing the corpus

I finished scraping the interior and then laid the corpus onto the back plate, positioning it carefully, adding spool clamps, and constantly checking the overhang all the way around. When everything was as close as I could get it, I removed a few clamps at the bottom block, used a thin palette knife to ladle in the hot hide-glue, and replaced the clamps, tightening them securely. I added more clamps over the glued area, then repeated the process for the next section on either side of the bottom block, and worked up around the sides that way: removing clamps, inserting glue, replacing the clamps and adding more…until it looked like this:

Closed Corpus for five-string double bass.
Closed Corpus.

 

I still had not put the magnets into the cover plate, because, when I added the reinforcements to the cover plate, it changed the curvature, and it no longer fits cleanly into the access port flange. (Rats, again!) So I kept wetting and clamping the cover plate in different configurations until I got it to a close fit, then I added the magnets.

magnets in cover plate
Here are the magnets in the cover plate.

 

Annnd… it turns out they are too weak. (Sigh…) I will have to order some bigger magnets after all.

At any rate, I was now ready to correct the overhang all around, and begin the final purfling.

Overhang corrected, beginning final purfling.
Overhang corrected, beginning final purfling.

 

Tracing in the slots for the final purfling.
Tracing in the slots for the final purfling.

 

The bottom end of the back plate has the same design.
The bottom end of the back plate has the same design.

 

Carving the Channel

After the purfling was completed, I still needed to trim back the purfling and carve the plate channel. This involved marking the edge crest all the way around, about 2 millimeters inside the outer perimeter, and carving the channel to barely touch that line. I used a sharp gouge, in the manner of a drawknife, to carve the channel, then used a riffler file to smooth the outer curve, where it meets the crest line.

Using a gouge as a drawknife, to carve the channel.
Using a gouge as a drawknife, to carve the channel.

 

(I actually made a very short video of how this works, but I was unable to successfully link it to this post. Sorry.)

After the channel was complete, it was time to begin final edgework:

Beginning final edgework on back plate of five-string double bass.
Beginning final edgework on back plate.

 

Beginning final edgework for the front plate of a 5-string double bass.
And the same for the front plate.

 

The goal is to make sure that the edge contour is correct all the way around, and that the plate channel fairs smoothly into the surface of the plate, without ridges or lumps. Getting the light at a low angle across the plate makes shadows which will show me where the lumps and ridges are so I can scrape them away.

Using shadows to complete edgework.
Using shadows to complete edgework.

 

It suddenly occurred to me that my bass-varnishing fixture requires that the end-pin hole be drilled, so I drilled the endpin hole but did not ream it to the taper it will eventually have. On smaller instruments I usually varnish before drilling the endpin hole, so that there is no likelihood of causing sags or runs where the varnish brush touches the hole. But on the bass, I have to have that hole as a place to attach the support for varnishing. (I can’t hold the bass in one hand, and the brush in the other, as I can with a violin!)

End pin hole drilled for a 5-string double bass.
End pin hole drilled.

 

And, that is pretty much where it sits, for the moment! The bass is ready for final varnish-prep, which will involve wetting down the whole surface to raise the grain, so I can sand it smooth again, then repeating until the grain no longer responds to moisture. Then I will rub in a compound to add color to the wood itself (not a stain, which might “reverse” the grain colors) and a mineral ground to close the pores in the wood. Finally a sealer locks in the mineral ground, and I will be ready for varnish.

So there is the bass corpus, ready for final varnish prep!

Five string double bass corpus ready for varnish prep.
Five string double bass corpus ready for varnish prep.

 

Thanks for looking.

Both Plates Complete: Front installed!

Back plate completed

Completing the Arching

When I last posted, the back plate was in progress, but even the arching was not completed, let alone the interior carving. Now it is all complete, the front plate has been installed, and the fingerboard, the neck and the tailpiece are underway! Things are moving along!

I did make a set of arching templates before moving on with the arching:

Set of cross-arching templates for the five-string double bass.
Set of cross-arching templates for the five-string double bass.

Those templates helped me to see the shape more clearly, and to know what changes to make, to improve.

So, here is the completed back arching, after scraping, so that you can see the flame in the Oregon Big Leaf Maple back:

Arching complete on back plate for five-string double bass .
Arching complete on back plate. Pretty wood, isn’t it?

Inside Carving

Carving the interior is always a daunting task…that is a lot of wood to move! But, one scoop at a time, it does get done!

Beginning the inside carving of the back plate for the five-string double bass.
Beginning the inside carving of the back plate.

 

Once I had the whole plate beginning to take shape, I carved “dots” all over the plate, checking thickness as I carved, until I had a pattern of correctly graduated “dots all over the plate. Each dot had a measurement written in the center, matching the graduation “map” I had chosen to emulate.

Then it was time to “connect the dots.”

Graduation
Graduation “dots” for back plate.

 

Connecting the dots for graduation of a five string double bass.
Connecting the dots.

 

Graduation of five string double bass back plate is nearly complete.
Graduation of the back plate is nearly complete.

 

It is always amazing to me how light the plates become after all that waste wood is removed. In this picture, you can see how thin the plate is, with the graduation complete.

Graduation of the back plate of the 5-string double bass is complete.
Graduation of the back plate is complete.

 

I took the plate inside, and stacked all the parts together so that I could see the progress:

All the main parts complete, and stacked on the garland of the five-string double bass.
All the main parts complete, and stacked on the garland.

What is next?

I needed to complete the neck, which means I needed to design, cut out, and shape the fingerboard and glue it to the neck block so that I could finish shaping them as a unit. Meanwhile, I could install the front plate, and get ready for the neck-set, once the neck was ready.

Front Plate installation

I completed a preliminary shaping of the blocks and shaped the linings, front and back. Then I carefully positioned the garland on the front plate, and temporarily clamped them together, using several spool clamps.

Garland and Front plate for the five-string double bass assembled and clamped.
Garland and Front plate assembled and clamped.

 

Then I removed the clamps from one area at a time, used a thin palette knife to slip hot hide glue into the joint, and re-clamped immediately, adding more clamps as needed. Then I moved to the next area and repeated that pattern. Soon I had the entire front plate glued, and secured to the garland with clamps.

Front plate and garland assembled, glued and clamped for the five-string double bass.
Front plate and garland assembled, glued and clamped.

 

And, when I removed the clamps in the morning, the project was beginning to look like a bass!

Front plate and garland for five string double bass.
Front plate and garland, with the clamps off.

 

I liked the looks so much, I stacked the parts together again, to see how it would look, all together. The back plate is just sitting there, again, not bent to fit the garland or anything. I will add purfling after installing the plate, I think, so I can be sure the overhang is correct, and that the purfling follows the finished edge.

Back plate sitting on garland assembly with front plate of five-string double bass.
Back plate sitting on garland assembly with front plate, and neck assembly.

 

There is still a  long way to go, but I will put more in the next post.

 

Thanks for looking.

Beginning the Back Plate

Back Plate Arching

Traced and cut out the Plate

When I last posted, I had flattened the back plate, using a plane, but the shape was still oversized.

Flattened back plate for five-string double bass.
Flattened back plate for 5-string double bass.

So I traced out the plate shape using a small section of plastic pipe as a guide, and a ball-point pen inside the pipe to make the mark. Then I cut out the plate using my very old Craftsman “Auto-Scroller” saber saw.

My beloved wife, Ann, bought me this saw when we had been married for less than two years, and it has served me well for the last 38 years, but this may be the final plate it will cut out. It overheated rather badly during the cut. 🙁

Back Plate for five-string double bass traced and cut to shape.
Back Plate traced and cut to shape.

 

Once the plate was cut out, I used my curved-sole scrub-plane to remove waste wood, and rapidly bring the plate to near the proper thickness around the edge. As the thickness gets close to the target dimension, I switch over to the Ibex Finger-plane with the toothed blade and the wooden handle, to complete the thicknessing of the plate edge. The Oregon Big Leaf Maple is much more difficult to carve than the Spruce was, both because it is harder, and because the grain is highly flamed, meaning that it changes directions every centimeter or so, resisting all efforts to smoothly plane off the wood. The toothed plane helps, but when I start getting close to the right thickness, I will have to switch over to a scraper before the tear-outs from planing are too deep to be removed.

Arching of the five-string double bass back plate underway.
Arching of the back plate is underway.

 

You can see the longitudinal arching template in the above photo: it is just a thin piece of plywood with an 11′-3″ radius circle section cut out of it so as to leave the correct arching height in the center. I used that to help me establish the longitudinal arching. The Ibex plane is on the plate, and the scrub-plane is almost out of sight behind a small block-plane in the background. The small block-plane is helpful for smoothing the ridges left by the scrub-plane.

I am working to the rough sketch I made before beginning, with the plan for the back arching: (I did change the plan a little. I realized that I could extend the arching a little further “north,” as I have tapered the entire garland a little, so that the bend in the upper bouts will not be so severe, and the arching may be able to follow it a little way before flattening out to avoid the compound curve. It’s worth a try, anyway, and will not hurt anything.)

Rough sketch of arching plan for the five-string double bass back plate.
Rough sketch of arching-plan for the back plate.

 

Arching of the back-plate for a five-string double bass still in progress.
Arching of the back-plate still in progress. Scrub-plane is more visible in this picture.

 

My hands and shoulders were getting too tired, so I went inside and used small finger-planes, files, and scrapers to refine the scroll. I am waiting on an order of carbon-fiber reinforcement materials to complete the neck, but other than that, I am pleased with how it is turning out.

Scroll for a five-string double bass nearing completion.
Scroll is nearing completion.

 

I also completed the scraping of the Sitka Spruce belly, and it is pretty much ready to be glued to the garland.

Front plate and Garland for a five-string double bass, ready to be joined.
Front plate and Garland, ready to be joined.

 

I pretty much wore myself out on this stretch: I’m looking like a tired old man, here. And I thought I was smiling…

The luthier with five-string double bass in progress.
The luthier with five-string double bass in progress.

 

Anyway…that is the current status.

 

Thanks for looking.

Commissioned 5-string fiddle

5-String Fiddle nearing completion

Custom Made Five-string fiddle Choices

Back in December, I received a commission for a new 5-string “Bluegrass” fiddle. It was to be made on the same form as one of my earlier instruments but have a two-piece, straight-grained Sitka spruce top and a very wild-grained Oregon Big Leaf maple back, sides and neck. The customer specifically requested Ipe for the Fingerboard, saddle and nut. Ipe is extremely hard, dense wood, but not threatened or scarce, as ebony is becoming. It has an odd color when under the knife, and leaves a bright yellow dust when it is scraped or sawn, but it finishes to a nice dark brown and darkens further with age.

Wild Grain Makes for Tough Carving

The last time I posted, I was just beginning the back plate arching. It was tough carving, as it is extremely “wild” flame, and the Big Leaf Maple grain is anything but straight. The result, of course, is some very beautiful wood. But it is hard work, regardless. The blades must be kept razor-sharp, and cuts must be kept shallow in depth.

The purfling requested was not only double purfling (favored by a few of the early masters, especially those of Brescia) but was to include a purfling weave, as well, in the form of a modified “fleur-de-lis.”  This is a design I came up with on my first five-string fiddle, and have continued to use, in a variety of forms, ever since.

Five-string fiddle Back Purfling begun
Working on the back purfling slots.

I like the look of the double-purfling and the weave, but it is pretty hard on my hands, as I still do all my purfling inlays by hand. I know a lot of makers use a Dremel-tool, or something similar. Perhaps I eventually will succumb to that “new-fangled” tool as well.

At any rate, here is the back plate, with the purfling complete:

Completed Five-string fiddle back plate
Back plate complete, ready for final scraping and graduation.

Closing up the “Corpus”

I closed up the corpus a few nights ago: all that is left to do before varnishing is to complete the final carving of the neck heel, and all the final edgework, so that the wood is “varnish-ready.”

Closed Five-string fiddle corpus, side view.
Closed corpus, side view. (Note the heel yet to be carved; edgework incomplete.)

 

Closed Five-string fiddle Corpus Back
Closed Corpus, back view…button still too long; heel uncarved.

 

Closed Five-string fiddle Corpus, Front view
Closed Corpus, Front view. Corners and edgework still not done.

I will show one more progress report during the varnishing process, and the last for set-up and playing.

Thanks for looking.