January 14, 2018 – Finished!
So after church today I wiped off the dried glaze of the Meguiars 21 sealer/glaze and the end result was passable, but not perfect. Buffed up the fretboard and then re-installed the tuner machines. So after 4 months and a week here it is:
I strung it up and played a bit. The obvious tune to play was “Helicopters”, my first composition and my only instrumental. Sounds good. The bindings are perfect and the finish overall is much better than when I started.
Then I disassembled and stored the spray booth for next time. Adding the two projects end to end I’ve been involved with luthier stuff for two weeks shy of the past year. Sure have learned a lot and I am better for it.
January 13, 2018
After a morning Boy Scout meeting and frittering away a couple of hour on a graphic design for my BBQ apron embroidery, I finally got to the polishing phase intermittently while watching the Pens hockey game. The entire guitar needed rubbing out and polishing. I started on the back then the neck, the front and finally the sides. Encouraged by the appearance of the neck I decided to do the back and front of the tuner head, which came as a dull finish originally.
Things progressed slowly but surely. It is heartening to see the mirror finish emerge from under the glaze. I a m getting my upper body exercise and hope my rotator cuffs can take the abuse. Man could I use a buffing wheel. By bedtime I had it as good as it was gong to get until I check with Eric. The back and neck are especially spiffy.
So then I cleaned up the fretboard with a little 1000 grit paper and scraping the top edges of the neck bindings to remove masking tape goo, overspray and traces of the stain I used to touch up the back of the neck. Then I pit on a coat of boiled linseed oil to seal it, wiping off the excess after a few minutes for it to soak in.
January 10, 2018
Began rubbing out the finish on the lower side and neck. Here is my lineup of sandpaper and polishing compounds: i had very good success using the 1/2″
foam that my banjo parts order came packed with for sanding blocks with two-sided tape to hold the paper. Just enough flex to keep from digging into the finish of=n the leading edge of the paper. I cut several sized blocks for use in different spaces. The Meguiars products do the trick of getting close to a mirror finish but I am still a step below Eric Sullivan’s results. I should be seeing him here in about two weeks to show him the banjo and that will be one of my questions.
By the end of today I had the sanding out to 2000 completed without going through any of the finish, particularly the binding joint and the colorized places on the neck. Perfect. I started with the 600 grit. As it turns out the final 1:1 coat on the neck is my best effort yet on an initially smooth sprayed surface. I needed to do much less sanding than I did on the side.
January 9, 2018
It’s been awhile off on other things, like car repairs, Thanksgiving in Pflugerville TX, deer hunting, Christmas in Avon IN, shoveling snow and the like but squeezed in here and there were a number of trials and tribulations related to the final spray finishing.
Just when I thought that I had the drop fills on the back and sides mastered the finish crinkled up around three of them when I sprayed on the 1:1 dilution, what I was expecting to be THE final coat before polishing. Did some research and found info on too high solvent content dissolving the thin edges of the underlying coat, which likely was the situation on the back. The drop filled areas were also perceptively lower, like saucers, in the rest of the surface. So I went back at it with 320/400/600 grit and two more full strength coats to the back and top. No more crinkling.
The next challenge was that while sanding down the bottom shoulder trying to level out a very small depression where the new edge binding met the original I sanded all the way through the lacquer to the wood. Crappo. By this point I know what that means – refinishing the entire bottom side. I resigned myself to doing that and at that moment decided to do a better job on the neck.
When the neck bindings came off early on they took some of the finish with them, which revealed that the Martin lacquer was colored and this revealed the lighter colored mahogany wood underneath. After fooling around with this to blend it into the rest of the neck color I developed a technique similar to Eric Sullivan’s water-based staining. I blended some very thick settled pigment from my old cans of oil-based cherry and dark walnut stains into a color that matched the rest of the neck and let the mix dry in a small old butter tub. I trimmed a model painting brush to a fine point and found that if I just wet it with mineral spirits I could get a thick dried stain pigment paste onto it that was opaque enough to cover the lighter spots on the neck. Then when you put a coat of lacquer on it the coloration binds right into the layer and the repair vanishes. This was a real victory moment for me.
Armed with this newfound confidence I prepared to respray these effected areas. I did a fairly contorted masking-off job to leave only the back of the neck and the bottom side from the rear strap peg around to the neck exposed. I settled on a 25% (3:1) dilution for the lacquer – enough to level it out well but not enough to crinkle anything – and then did some thinking about just how I could spray it in a booth that was really not big enough for a guitar (made it for the banjo and it needed to fit on a 4′ wide table). The solution was to add a view window and a set of arms/gloves on the opposite side so I could spray from both sides. This was especially important for the neck – to get it from both sides equally, since I wasn’t rotating the guitar to paint the top and bottom or both sides. I had managed to spray from just the one side earlier but it was less than ideal, which had bugged me.
The results were excellent, which is usually the case when you put in the sweat equity with preparation. Here are pictures of the modified spray booth and the end product before the final coat. By the way that low spot in the binding joint is gone also with the re-coating.
September 15, 2017
First round of scraping and sanding down drop fills, then repeating the fill to bring it up flush. It normally takes two fills to get enough thickness to get the low spots flush. I also decided to do two very small dings on the top.
September 14 – Drop Fills Again
If you have read the Banjo Project blog you already know about drop fills. You use some kind of eye dropper to place drop of lacquer in a small low spot, nick or imperfection, and then scrape/sand it down when dry. I use a syringe, which is very precise.
The top back shoulder of the body sustained a major nick somewhere along the line that chipped the finish off down to the spruce. The primer and 5 coats later there was still a small depression in this area, so I drop filled it this morning. When that dries I have a couple locations along the new bottom back
binding to do the same thing with, only these are low spots where the purfling didn’t quite match the height of the edge binding. When these locations are filled in, then it will be final finish time.
September 9, 2017
Finally got onto the sanding and prep for spraying. Standard practice is to apply one coat of primer then lay down 4 – 5 coats, and use 320 grit to scuff between coats. Thinning helps the flatness of he surface but is not super-critical until the final topcoat, which is applied in a 1:1 dilution. I found that with the Behlen lacquer I am using thinning 20% for the build-up coats is preferable.
So I had to come up with some way to hold the guitar in the booth for spraying while still allowing it to be rotated so that I can do the entire body and neck at the same time. Here is what I came up with:
What is cool about this is the painting order – front side, rotate to opposite side, rotate to top then rotate to the back. I can get the neck from this last position. In other words you can spray the entire body and neck in one operation. Also the effect of rotating to each position lessens the change of runs or sags considerably. I’ve had none so far (knock on wood!). I modified the rack from the above picture by cutting down the extensions on both vertical supports to get clearer access to the tail end and neck for spraying at their support points.
I learned from my earlier banjo project (that blog is also here at this site) that the best setup for my HVLP sprayer (Harbor Freight) is full open with a flat pattern at 25psi. I am careful to have 25psi while actually spraying, not when deadheaded in the line when not spraying. The gauge reads 30psi deadheaded. This setup and 20% thinning gives a reasonably smooth surface for these buildup coats. I also have learned that with this pressure the lacquer flow is slow and I need to do 6 passes to get the thickness that will level out smooth. I can do 6 passes without runs or sags, too.
So with 5 coats on its wait around time, a minimum of 48 hours to allow the finish to cure and harden before the final topcoat. Lacquer may set up to the touch very fast (5 minutes or so) but it takes a long time to fully cure and harden. In this case it needs to be cured well enough for the wet sanding using 400-grit and mineral spirits before the topcoat.
September &, 2017 – Paint Booth Blower Upgrade
To this point the spray booth has been exhausted by a radial blade window exhaust fan. It is basically a 9″ square fan box taped onto the outside of the booth and connected to the exhaust vent with a cardboard cone. It was time to upgrade the the fan to a centrifugal blade type for a better exhaust rate and better performance against higher back pressure. I found a 0.45 amp, 115V Dayton blower that delivered 68 CFM against 0.2″ water pressure that was perfect. After refitting the former square opening from the booth to a 3″ hole I found a PVC pipe adapter to transition the 2″ outlet to the 4″ flex duct the setup looks like this now:
The plastic sheeted sides of the booth are definitely bowed inward now with this increased exhaust volume.
September 6. 2017 – Near Catastrophe Avoided
Today was masking off and primer day. Things were going along simply enough. I decided to mask of the edge bindings of the neck along with the bridge and pickup jack in the tailpiece. After I put the first strip of masking tape on the bottom side of the neck I decided to move it slightly. Working to peel of the tape to move it, oh no, it pulled off the whole binding. It was apparently not well attached. Fortunately I noticed it right away before I cracked it at the bottom end. I was able to put it back down and then peel the tape from the other end and at a right angle to its length. That was close. So it was repeat the gluing, stretch tape clamping and squeeze out trimming. In the end only a bit of the finish was lost from the neck and with a little staining and the primer I had it repaired. So now refinishing the neck was a necessity not an option.
September 1, 2017
A trip to visit Nate in Colorado Springs and hike in Rocky Mountain NP, some other more pressing home projects and here we are another month down the road. Time for sanding, more scraping, more sanding and then spraying.
As I launched into scraping the repaired edging I made a decision to refinish the entire guitar. There were two serious chips in the finish down to the wood in the upper shoulder of the top and various scrapes, dings and scratches distributed on all surfaces. A corollary decision then was to scrape all of the edging to match the new repair.
One problem in instrument finish repair is that part of the beauty and value of an old instrument comes from the yellowing of the lacquer with age. Some master luthiers have ways to darken new lacquer prior to spraying it, but not this novice. This is not too much of a problem with the wood since I am not stripping it down completely and the rosewood is so dark anyway, but it is on the pearly white edging. My decision was to scrape ALL the old edging down to match the new white ones. Besides not having the skill to color the lacquer there were two other reasons: 1) the existing lacquer on the old bindings was seriously chipped, one reason being that the finish from an earlier factory repair was too thick and poorly done (as already discussed), and 2) in this previous repair the top edgings were already very white compared to the back and neck. So it was a 50/50 situation. Let me say that it takes a long time to scrape down the old yellowed lacquer on all the edgings all the while being careful not to break through to the wood on the adjacent edge, also while chamfering the old finish down into the line of the edging.
August 2, 2017
Scraping is in a word tedious but the end result is satisfying. Impatience is not good because you can’t put it back on after you’ve taken it off. The scraping also involves the adjacent lacquer finish because what you are after is a perfect match in the lines before sanding and refinishing.
July 29, 2017
Not a lot happened on this project in June or July with Boy Scout Camp, making ash canoe thwarts for my friend Mark and granddaughter Sarah’s birthday and all, but here I am back at it
So the first step is to decide where to cut the loose purfling/binding back to and where to put the joints. as it turns out the plastic material is not acetone soluble, so the joints will have a hairline in them. I decided to cut them back to the shoulders and stagger the joints to help hide them. The other extreme option would be to remove them all the way back to the neck in front and tailpiece i back to have no joints. However, since the reason the edges came loose in the first place is because they shrank and pulled away I decided that a joint at each end would allow them to shrink without pulling away in the future. Also when I got to checking closely I saw the previous factory repairs had done just that.
I decided to use Bind-All adhesive from StewMac.com, the stuff made specifically for this job. I also took their recommendation on using their orange stretch tape for clamping the bindings while they set. Cutting thre but joint carefully did the trick. I had a bit more squeeze out than I wanted, but no serious damage that couldn’t be cleaned off. Better stuck good than sorry. Getting all three pieces in place with the glue one at a time was a bit nerve racking because squeeze out in the grooves would be a problem. I glued and clamped each one down in sequence and then scraped out the remaining groove for each one when the glue had set. So here we are glued and clamped then dry and ready to scrape them down to match the existing bindings.
June 8, 2017 – A Starting Point
The picture shows the guitar at present. I’ve manged to cut out the damaged binding/purfling and clean the grooves of old adhesive.
Bindings and Purfling
The edge binding and purfling I am using are both made of styrene plastic I believe, soluble in acetone. The binding is a simple white, but much thicker and sturdier to hold everything together and protect the edges of the wood pieces on the outside. Purfling goes inside the binding to add style and color. I think historically purfling was made from wood. There are two types of standard Martin plastic purfling – a black/white/black/white and a thinner white/black/white. The standard D-35 design uses both. So the repair will actually be a three-piece affair.
A Poor Paint Job
You can see that I have been working on the old finish. This became a bit of positive encouragement from a discouraging discovery – the guitars final finish is not adhered to the undercoat. I remembered once into this that several years ago this same separated edging problem occurred and I returned the guitar to Martin for repair under warranty. You see, when I bought the guitar in 1972 it came with a lifetime original owner warranty for workmanship. So what I am diving into I could be having done for me for nothing, except that #1) I’ve already messed with it, #2) I love the challenge, and #3) whoever refinished the guitar the first time didn’t get the finish to adhere to the underlying coat and it is peeling off as I sand it. So maybe I’m not such a novice after all – I can do better than that. I have not found the full extent of the peeling yet but that will come. I don’t think it will add any extra finishing area to the project .
June 7, 2017 – A Luthier Urge Rising
The satisfaction I had from building the banjo, and the knowledge I gained, encouraged me to tackle the repair of the bottom back edge binding and purfling of my 1972 model Martin D-35 6-string. The plastic binding can shrink with time and pull away from the body of the guitar, which it has on the bottom edge and did once before. Unfortunately, I launched into trying to simply clamp and re-glue this section early on in the banjo project with poor results. I sanded through the finish in one spot and basically ruined the binding and purfling in the area. After that I did more online research and got the straight story on how to do it at www.frets.com.
I was able to run down the binding and purfling at C.F. Matrin’s 1833 Shop and received that a couple weeks ago. After some study I decided to use a binding tape for clamping and binding adhesive (Bind-All) from www.Stewmac.com for installing the new sections. Fortunately the spray booth I built for the banjo work is big enough for the guitar. I am going to upgrade the booth’s exhaust fan to a real centrifugal fan before I start this refinishing.