I’m painting the guitar Olympic White, with a nitrocellulose finish. All the prepping materials and paint are from Steve Robinson at www.manchesterguitartech.co.uk/. His tinted clear coat worked out well, and if the rest of his stuff is of similar,excellent quality. Using good quality materials always helps confidence, and that should help towards a pretty good end result – just as long as I take my time with the process, and plan well in advance.
First off – I have to rub down the guitar body, and check it over for any problems. On examination, there are a couple of very small dings which I might just be able to fill in with primer – but nothing too worrying. I’ve previously rubbed the body down with 400 grit paper over a cork backing block, and once I was happy with everything, I masked off the neck recess and attached a piece of wood as a handle. This, specially shaped “painting stick” acts just like a section of neck, and attaches to the neck screw holes already drilled in the body. I can hang this in the spray booth, or use the handle to manipulate it while I spray.
The body is a 2.14kg piece of alder. Actually – it’s two pieces, but the join is all but invisible. Alder is a good tone wood for guitars, and standard for a lot of Fender guitars. Alder is easy to work and machine but, as with most woods, it’s always best to seal any of the pores and grain before painting, so that they don’t telegraph out through the layers of paint finish. Some woods, such as mahogany, have such well defined grain and pore structure that it’s necessary to fill the grain before proceeding – but with alder, it should be possible to prep the surface adequately using just sanding sealer and a good primer.
I applied three coats of sanding sealer. It’s in a spray can – just like the paint, primer and clear coat. Two coats of sealer might have done the job, but I had enough left in the can, so I went for three. The first coat takes almost half a can, since the wood literally drinks the finish in – especially on the exposed end grain. I paid special attention to the end grain on the edges – especially at the neck end and at the base. I also made sure the coat went on as evenly as possible – with a number of light passes making up a complete coat. It doesn’t take the sealer too long to penetrate the wood and tack dry, but I left it a couple of hours to work in, before rubbing eveything down with a medium grit paper over a cork block, on the flat faces and edges. You have to take care not to sand too heavily on the edge contours – the idea is to rub back any inconsistencies on the surface, and to key in ready for the next coat. Going too heavy risks rubbing right through into bare wood again. The image above shows the body just before it’s second coat of sealer.
After three coats have been applied and rubbed back, I cleaned the body off with naptha, and then wiped everything dry to make sure I hadn’t left any surface contamination. This might prevent proper paint adhesion. Then, a light coat of primer goes on to act as a key for a first proper coat. A light “mist” coating is often the key to getting good adhesion between different layers of a good paint finish – so I figure it’ll not do any harm here. After the primer has dried, a second coat is sprayed over – by which time the body is evenly covered over with white primer.
Now is a good time to go over the body closely, and to rub back the primer, again with 400 grade, or similar, over a cork block. Now I can see if the small dings have filled in. There are a couple of inconsistencies right on the edge – so I gently sand them smooth – taking care not to rub through the sealer too much, and down to bare wood. While I go over the body, I notice a couple of areas where the routing for the edge profile looks a little squarer than I’d like. Part of the look of the Jaguar is the flowing curve along the back and edge – so I spend a little while rubbing the curves so they look and feel to flow properly. I go through the primer coat – but again, I try to make sure I don’t go too far back through the sealer coat.
I also notice one of the imperfections I noted earlier hasn’t really filled in. I mix up a little white, two-part filler – fill the imperfection and sand it level with the surround.
Then it’s on with more coats of primer. The general rule of thumb is to always build any paint coat up in stages. In this case – roughly three coats a day, each with about two hours drying time, in-between. Each full coat consists of a few, (ideally three), lighter passes. The technique aims to apply a thick enough coat, but not too thick that it sags or runs. If you spray too far away, the paint turns to dust before it hits and you end up with a dusty, badly adhering surface. Too much paint, or too close, and you run the risk of flooding the surface and causing sags and drips in the paint skin. If you take your time, you can avoid most problems, and it will repay you in hours of saved time, in not having to fix faults. But if you should run into problems, it’s important to fix them as you go. Rub back to a stable surface, clean off any possible surface contamination or loose material, and then build up the paint skin again in stages – gradually feathering-in the new finish, to the surrounding.
Once the body is well coated in primer, a good sand down provides a smooth finish on which to build up the paint. It’s the job of primer to act as a key for the actual finish paint to adhere to – so you can use 400 grit here to provide a nice looking, uniform matte coat. It’s always worthwhile taking your time in rubbing the body down. You’re going to be doing a lot of this after all, when it comes to polishing. It’s a good time to go over the work in detail and get to know it. You can spot any potential problems at an early stage, and sort them out before they become real headaches. You can also work out how best to apply the paint – whether it’s better to hang the work or lay it flat.
For this job, I ended up going for the option of spraying the piece at arms length – held and manipulated by the painting stick. For each coat, I sprayed the edges first, making sure the inside of both neck “horns” get enough of a coating. (It can be quite fiddly getting the paint spray in there). Once the edges are well coated, it’s easy to do each of the sides in a series of passes, with the spray slightly angled onto the surface. I’ve installed a hook in the ceiling of the spray area, so I can safely hang the body to dry, in-between coats.
Usually, the finest results are achieved by rubbing down and re-keying after each paint coat – but it seems that nitro paint doesn’t really always need this. Each coat sort of melts into the previous coat, turning it to a sort of gel, before going off and re-solidifying quite quickly. This is partly what goes to make such a hard-wearing coating – but it’s also what makes working with the stuff a little more complicated.
Firstly – the paint is solvent based. Always make sure your work space is properly ventilated, and make sure you put that fag out. Secondly – wear a proper respirator. The vapour that comes off this stuff is noxious, and you don’t want to breathe it in. Get a respirator with activated carbon organic filters, and change them regularly.
And so it goes. Coat after coat, gradually building up the paint surface. Of course – it being an all white guitar – all the tiny black fibres in the area will try and get in your finish. If you spot them, (and they usually appear stuck in the last coat you sprayed), lightly rub them out between coats with wet and dry paper, and a little naptha. Use a pad behind the grit paper if necessary, to avoid creating dips and divots in the flat surface. Wear cotton gloves if you can be bothered, (another tip from the framing trade). You don’t want to contaminate the surface with grease or moisture from your hands. After rubbing back – always make sure the surface is clean, dry and dust free. Then, move on to the next coat.
My finishing schedule follows what is roughly referred to as a “Rule of Threes”. It means I can break the process down over a period of time to plan my days, and allow for each coat to go off properly. This leaves lots of slack time to be getting on with other things – but basically, the process is as follows:
Sanding sealer – three coats. Each coat consists of three lighter passes. Leave two hours between each full coat
Primer – three coats. Each coat consists of three lighter passes. Leave two hours between each coat. Rub back each coat as required to level and remove inconsistencies and dust.
Paint – as many coats as it takes. You should be able to get a good opaque coat from a single can – but I’ve budgeted for two cans – just in case. Obviously, the better you get at painting, the fewer coats you tend to need. Many people speak of the advantage a super-thin coat of nitro gives to the sound characteristics of any instrument, as opposed to a thick coating. Each coat of paint consists of approximately three, lighter passes. You want to leave the surface looking wet and consistent – but not put too much on to cause runs, sags or obvious spray marks. Start each spray pass off to the side and keep the spray moving over the body until you stop spraying – having passed over and off, the piece. Then repeat, with the spray slightly overlapping the previous pass. Again – watch the distance between the spray and the work. Keep it consistent, and keep the spray moving consistently. Eventually you kind of “get” the feel and the rythmn, and it becomes second-nature.
After each set of three coats, leave the work to dry a couple of days before doing the next three coats. The nitro shrinks back as the solvents evaporate out and the paint layer “degasses”. By leaving it to hang a bit, you’ll help eliminate the possibility of “pin holes”, which can be caused by trapped outgassing, or moisture contamination. With the weather set fine the way it is at the moment – this whole painting and finishing run might well take a few weeks – but now’s the time to get it done, while it’s warm and dry.
Once the painting is done, and the result is a consistent, smooth paint coat with no bits of dust or fluff – give the piece a final, good, close examination. You’ll probably notice a kind of uneven appearance in the paint finish which looks a bit like orange peel. This is OK – it’ll almost always appear to come and go as the piece dries and the nitro shrinks back. If it doesn’t disappear – there will be time enough to level it back with some grit paper. Set the body aside to dry properly for a week or so, and it should be ready for clear coating.