This week I applied the colour to my guitar build, I also started the finishing process on a kit that I purchsed from guitarkitsdirect.com as well as continued to work on my Squire strat, the first guitar I ever owned, the finish was in a sorry state so it was a good practice model.
The colour has been the single most stressful part of this whole experience, Mirotone make pigmented lacqeurs, but at $40 for a 4L tin it seemed foolish to buy 4L in several different colours when I only need about 300ml for each guitar. You can also buy acrylic lacqeur in a range of colours from a spray can, but again I already had the nitrocellulose and the spray can finish isn’t quite as good as that of the spray gun. Also for one of the kits I have comming I wanted to make a custom colour, so I set about trying to find pigments to that were compatible with my nitrocellulose finish to mix in to make the colours I wanted. Australia is not a great place to do this at all! In the USA places like Stewart Macdonald have all the colours you could want however the only guitar laqceur specific dyes I could find were analine dyes, these are transparent and wouldn’t have worked.
So eventually I had to threw caution to the wind, I found a hobby site, Dalchem, they had both transparent and opaque pigments for addition to polyurethane resin, given that my guitar finish is basically a thin version of resin, (nitrocellulose in my case not polyureathane) I purchased some opaque white and black as a base and some transparent colours to add to these. Luckily for me they were perfectly compatible! The white especially required quite a lot of pigment to be completely opaque but I wasn’t worried, the pigments were only $15 each so I saved myself a lot of money and also gained the ability to make custom colours, I’ll talk more about applying those later on though.
At the end of last week I had done all the sanding, washcoating, grain filling and barrier coating which meant it was time to apply colour to the guitars. As you may recall I decided to keep the top of my guitar a natural finish so you can see the wood underneath, the back grainfiller did a great job of accentuating the pores but I still wanted to spruce the appearance up a bit. For this I used a transparent stain from feast and watson which was available from bunning, I used elm as the colour as it wasn’t too intense but had a nice golden colour to it. Rather than staining the bare wood (which looked terrible on my test on scrap) I added some of the stain to lacqeur in a fairly thick mix and applied two coats. If you compare last weeks wash coat only with the new colour you can see the diference it has made.
With the most important part of the guitar (visually speaking) taken care of it was time to colour the back, although originally I was going to make the back transparent black I decided it would be easier to make it opaque. When laying down a colour coat I decided it would be best to first lay down a primer. This is a pigmented coat that is sanded to a smooth finish using the 360 grit sanding paper. For lighter colour coats a white primer is common, and for dark backgrouns a grey primer is prefered. Because I was using black, I decided to make the grey quite dark so I added one mL of white and 2mL of black pigment to my lacqeur which was a 2:1 lacqeur:thinner mix. I laid it on wet, this means it’s a bit thicker and shines when still wet, the wash coats being thinner were laid on in a drier more sparse spray pattern to avoid runs. Before spraying the primer I masked off the top of the instrument as well as a little of the sides in order to make a binding like effect using painters tape and plastic liner.
I sprayed the first coat a little too thick in some places which caused runs, build ups of lacqeur, which needed to be sanded out after an appropriated period of drying to let the finish harden, I sanded the whole primer to a really smooth finish using the 360 grit sand paper which meant that a more even smooth colour coat could be applied. You don’t want to have to modify a colour coat because the sanding and imperfections will show through once the top coats are added. Having learnt from the previous experience with coating I made the black lacqeur and sprayed it on being careful not to spray it too thick and managed to avoid runs.
After the colour is applied I left it overnight to dry and harden. I then began the process of applying the top coats, these are thick (2:1) coats of clear lacqeur. You apply 4 -8 coats spread over a few days in order to build up a protective layer of finish that is thick enough to accept the buffing compounds without burning through, I’m currently on the 7th coat, tomorrow I will add one final coat and then let the finish harden for 7 days before beginning the final sanding and buffing process.
In between coats there was a 1 – 2 hour gap, this meant that I also had time to work on the headstock of the guitar, I will talk about that in a different post though. I am really close to the end of the process now with only the buffing, components and the electronics left, as well as the creation of the top and back control plates. It feels good after weeks of work to finally be getting closer to that finish line, I can’t wait to post a video of the guitar in action!
Guitar builds are typically split into two stages, the first stage is called the manufacturing phase, this is essentially the woodworking phase, timber is planed, glued, shaped and routed. The second phase is known as finishing, this involves meticulously prepping the wood with progressive sanding, and spraying lacquers or applying stains and oils to protect the wood. After finshing the manufacturing stage earlier this week I moved onto the home straight and began the finishing process.
The first step is to sand the wood, I had a few dings and scratches so I started off with a coarse grit, 60. This is pretty agressive on the wood, it takes out a big layer and creates fairly deep scratch marks, though less deep than the dings I had introduced. I used the 60 grit to create a back contour also, this is for comfort while playing, the contour lines up with the players abdomen and makes the guitar nicer to play, especially whilst playing standing up. The next step is to use the 120 grit paper. The 60 grit took care of all but the deepest marks that I had accidentally created during drilling the bridge holes, the 120 smothed off the wood and removed the rest of the holes that were amenable to sanding. At 120 the wood is still too rough to achieve a nice base coat so 240 grit is needed. Before sanding with the 240 grit I made the wood slightly wet with a damp cloth in order to raise the grain fibers of the wood, this produces a smoother finish and makes sanding easier. I also rounded off all the edges front and back to create a less sterile feel to the guitar, the straight edges weren’t looking too great. To save myself time and effort I used the orbital sander for this task, I also think the orbital sander produces a more consistent and smoother finish, for the wood stage it removes a fair amount of wood which is good. I intentionally started out with a thick guitar so any dirt that ended up on the surface during manufacturing could be removed with a bit of generous sanding.
There are many ways to finish a guitar, some people like to use brushes and rags to apply finish materials, others use products in an aerosol spray can. Most people agree that for professional looking results you need an air compressor and a spray gun. This method allows you the most flexibility in finishing materials because you can mix your own and add it to the spray gun at what ever consistency you like. I decided to invest in the spray equipment, I’m glad I did, not only has it poduced good results so far, but the air is handy to have to blow away dust that is hard to remove with a cloth.
There is no one true way to finish a guitar, the neccesary steps can be applied in different orders depending on what kind of look you are after. I have used the book “Guitar Finishing Step-By-Step” along with the accompanying video and I must say it has been esential. I knew nothing about the finishing process and by reading the book and watching the video tutorial I became much more confident and have learned enough to develop my own method for how I want to finish the guitar.
Although in an earlier post I said I was going to use polyuretane lacqeur, after more research I decided that a nitrocellulose type laqceur would be best, it’s easier to sand, buffs to a shinier gloss and can be applied thinner which affects the tone slightly. It wasn’t easy to find, in Australia you cannot simply purchase it from your local hardware store, however thanks to an internet forum search and a discussion with a local luthier I found Mirotone and purchased a 4L tin of laqceur and the reccomended thinner.
Ash is a very porous wood, this means that if you were to simply spray your finish straight over it you would end up with a pitted uneven finish somewhat like a golf ball. In order to counteract this a grainfiller is needed. Based on the internet research that I have done I decided that it would be best to start off by spraying the whole finish in a wash coat. This is a very thin coat, 3 parts thinner to 1 part lacqeur (3:1), sprayed over the whole body to seal off the wood and protect it from whatever you do afterwards. I sprayed 2 washcoats over the entire guitar, even after these two thin coats the guitar already began to look better.
The wash coats covered the pine nicely and did fill some of the pores, grainfiller was still needed though to fill the rest of the pore holes. Originally I was going to use Feast and Watson sanding sealer but after testing it on an old guitar I have decided to refinish I found I didn’t like the way it looks or the way it sands. Timbermate waterbased grain filler seemed like a popular choice in Australia and was available at Bunnings in a variety of tints, I decided to be adventurous and went with black. I thought that this would really make the pores pop being such a darker colour than the surrounding wood, not to mention I am planning on tinting a layer or two of the top coats with a stain so the dark will be even more helpful to make the pores stand out.
The grain filling is achived by basically dolloping the grain filler onto the guitar and then spreading it across the grain with a plastic applicator and wiping off the excess. It dries very quickly but does wipe off for the most part with water, I found however I was also wiping the filler out of the pores so I filled the grain a second time with a thick mixture, filling the holes with the applicator and wiping the excess down the sides to fill the pores that are on the side of the body that the applicator cannot reach, I let it dry thick and then sanded it off leaving only the wash coats below and the filled pores.
In order to seal in the grain filler and to fill the remaining depth from the pores that the grain filler was unable to fill I applied another two wash coats to the guitar. With the wash coats the guitar is looking more like the final product. The next step will be to apply more wash coats and then a layer or two of the tinted laqceur on the front and transparent black pidmented laqceur on the back. After that it’s just the clear top coats and the buffing, more on that next time…