Kurt Cobain “Jag-Stang”. Polishing a nitro paint job the easy way

My paint job and clearcoating on the Warmoth JagStang body has now had about 9 weeks to properly cure. Meanwhile I’ve had my vision all-but restored to what it was, with another implant. After a couple of years of cloudy, blurred vision – it’s quite stange being able to see clearly again. No excuses now – I’ve got so many things to catch up on…

Because the body was quite well prepared already, by the time the paint went on – the finished lacquer is already quite smooth, with little evidence of any “orange peel” puckering, or other irregularities. The only anomaly of real note, appears to be a couple of areas, one on each side, where the final coat of clear lacquer has dried with something of a matte “bloom”. This might be due to some residual moisture in the air getting trapped under the final coat – but it might also be down to holding the rattle can just that little bit too close. Either way – the bloom should polish out relatively easily. Importantly – it’s in the clearcoat, and not in the coloured paint layer below.

JagStang body – Cured paint and clearcoat (2 months)

Because I’ve tried to apply a relatively thin paint and lacquer finish on this job – I’m a little concerned that my usual polishing approach, (flat sand from 800 grit, and then work all the way up to 12000 micro mesh), might prove a bit too agressive. Because the finish already shows good signs of a flat, high polish in places – all I really want to do is level out any minor inconsistencies, and then get to a finished shine as quickly as possible. I’ve been looking at some of Steve Robinson’s finish tips, at manchesterguitartech.co.uk , and I’m intrigued how he seems to have managed to shorten the polishing process – yet still, apparently, achieve a really good finish. I’ve already tried out a few of his tips, and want to see if I can formularise a shortened polishing approach, starting with my current bunch of builds.

JagStang body – Lacquer coat before flat sanding

The slight matt “bloom” in the final clearcoat is quite tricky to photograph – but is just about visible in the image above. You can see how glossy the finish is otherwise, and how few inconsistencies there are generally. The colour coat underneath was flat and consistent, so all of the inconsistencies are in the top coat. Hopefully – a light flat-sanding all over, will help bring the surface together.

Since I’ve been preparing the body thus far with a 350 grade “Mirlon” pad, and 400 grit wet and dry paper – there’s no real point starting to flat sand with anything less than 800 grit. 800 is about the point where papers stop “cutting” and removing much material and, instead, start to refine and polish. However, it’s important to remember that careless wet sanding always risks the papers “sucking” down onto the finish, and cutting all the way through thin lacquer and paint coats. This surface, after lacquering, displays only a slight spray texture in places. All of the major level inconsistencies have already been worked out during the priming and prep stages, so I should only be dealing with minor textural differences in the lacquer coat. A gentle once-over with 800 grit – using a pre-soaked paper, and a little additional water as a lubricant – is enough to impart a consistent, dull sheen all over the body. There are no real low spots, and so there aren’t expected to be too many areas which will need significant work.

The edges are carefully worked, as well as the main faces of the body. The radiused edges are barely touched. The flat faces are flat-sanded with the abrasive paper backed by a cork block, which itself has gently rounded edges. The radiused edges are only worked gently, with the paper simply wrapped around a finger. I’ve pre-drilled the body, so that the paint finish has covered the screw hole openings and countersinks. However – it’s still important to try and prevent any of the lubricating water from penetrating the wood of the body, where it can get under the lacquer coat. This risks lifting and cracking the lacquer, as the wood swells, and then shrinks as the dampness dries out. Consequently, I try to keep all of the screw holes and routs as dry as possible at all times.

JagStang body – Flat sanding in process

The image above shows the effect of flat sanding, and also shows a few localised low spots – just below the tremolo spring recesses. Any odd areas like this which display low spots, are gently worked with care. In areas such as this – it’s best to work carefully, and to use a smaller backing block, if it helps. The danger is always that, in working a few low spots too much, the edges of the sanding block also begins to rub over the surrounding area. It’s best to use a much smaller block, and to try and randomise the action as much as possible over the immediate area.

JagStang body – Fine sanding

Once the entire surface has been flatted-back consistently – the finish has a uniform, dull sheen, and the colour looks true and consistent. The next step is to lightly repeat the process, but this time with 1000 or 1200 grit paper. For this pass – there’s no need to focus on levelling the surface. This time, the emphasis is on beginning the polishing process. The intention is to reduce any noticeable fine scratches or polishing marks, and to smooth the surface, ready for ultra-fine polishing.

JagStang body – Polishing

No matter how carefully the grit papers are used – there always seem to be a few witness marks left behind. It’s important to clean the body down before moving on to each, finer stage of polishing, since this makes sure any stray specks of abrasive can’t contaminate the next, finer grade. But even then – somehow there always seem to be a few scratches and fine lines which persevere. If they’re not rubbed back – they might end up getting “locked” into the finish. There are a few such lines evident here, and I think the edges of the grit papers can, sometimes, drag across the surface – behind the flat backing area. Working into a light helps spot potential issues like this, at an early stage.

Once the body has been completely sanded to 1200 grit – I find that a gentle rub over with a grey, 1500 grade “Mirlon” pad helps to further “regularise” the finish. The sheen seems to become much more consistent, and it’s possible to work on individual, stubborn marks, and to begin to “feather” and blend the whole finish together. Because this is essentially a polishing step – I find it’s better to use the pad lightly, without a backing block – and to gradually work the faces into the edges, over the radiused edges. The sheen seems to come together quite quickly, and by working into the light at all times – it’s possible to see the shine of the polish job, beginning to emerge.

JagStang body – Fine polishing

Normally – from here – I’d continue passes with progressively finer polishing cloths. However, since each subsequent step would remove a little bit more of the surface, and since there are still a significant number of potential passes to get from 1500 to 12000 grit – each step further risks rubbing through that finish. Since the polishing process can also develop some heat – there’s a further danger that the lacquer might soften slightly, and as it gets thinner…

So, I’m going to try something I used to do when spraying my own motorcycle finishes – and that’s a pass with automotive rubbing, or cutting compound. I’m using a fine, proprietary cutting compound from Halfords, and applying the stuff with a clean cloth. It’s a chalky sort of paste which, once applied, can be worked lightly with a wet buffing pad. You can hear it cut as you do so – and gradually the whole surface is rubbed back, until the surface begins to show something of a shine. I find that the paste tends to leave a cloudy residue, which only really lifts when the body is carefully cleaned over. By carefully wiping the surface clean with a wet cloth – the effect almost seems to be one of a fine water polish. The effect on the lacquer finish, is to rub out some of the more noticeable sanding marks and scratches, and to begin to bring out a distinct gloss reflection. Once again – once the desired effect seems consistent over the entire body – the guitar body is thoroughly cleaned down.

JagStang body – Swirl removal

The next step also derives from an automotive finishing type schedule. Swirl remover, or T-Cut scratch remover, is perfect for rubbing out any fine polish hazes. As the shine becomes more “liquid” – there’s often a fine haze of polish marks left in the lacquer coat, and these can spoil the effect of a “mirror” finish. A swirl remover reduces this haze to an absolute minimum, and it’s sometimes possible to remove it almost completely. Again – it always helps to work into a light source, and to work over the body carefully and meticulously. Steve Robinson recommends T-Cut, applied with a mutton cloth. I’ve tried the method and it works – but it does take a fair bit of rubbing. I’ve also tried using Meguiar’s Swirl-X 2.0 – and personally – I find it much easier. (The swirl remover also seems to work quite well on polyester finishes).

The Swirl-X is, essentially, an ultra-fine rubbing compound. Applied with a soft cloth, it soon dries to a chalky finish. I find that rubbing it off with clean kitchen towel, seems to soak up any moisture in the paste, and also helps the compound cut. You can often hear an audible “squeak” as the abrasive does its’ thing. With the swirl remover – it seems possible to develop a rich, glossy, liquid-looking shine quite easily. Spread it on – let it dry – rub it off. Of course, it all relies on the effectiveness of previous steps – but there’s quite a sense of achievement when the swirl remover is rubbed off, and the professional-looking finish underneath, is finally revealed.

JagStang body – Wax polishing

The final step is to apply a non-silicone polish. Again – I tend to go the automotive route, and use Meguiar’s Carnauba Wax polish. A couple of coats of polish are applied, left to dry, and then hand-polished with a soft buffing cloth. A final coat can then be applied, and worked with a hand-held rotary car polisher. Once again – remember that polishing creates heat, and that heat can damage a lacquer coat just as much as too much grit can.

The effect after the polish is excellent. When finely examined into a light source – there are just a couple of areas remaining, which each display very slight textural or clouding issues. These are completely lost when viewing the guitar body under normal conditions, but if they’re deemed “unsatisfactory” – it’s an easy thing to address each small area separately. The finish can be carefully taken back to an earler step in the polishing, and then carefully re-worked so that the repair blends in seamlessly with the surrounding. There are only a couple of areas which slightly disappoint me – but I’ll leave them for now, and see if I begin to “forget” about them, as I move on with the build. Sometimes – in focusing on any particular fault – it’s possible to “lose all reason”, to become over-obsessed with a single, tiny detail, and to keep “picking” at it. So much so, that any single, slightly perceived imperfection can gradually become much, much more of a problem again. You have to look at the whole thing in balance, and ask yourself… “is that really a problem…?”

JagStang body – After polishing, ready for fit-out

For that reason – it’s useful to take a break sometimes, and look at things with fresh eyes. By the time focus is on the next task – some “problematic” issues seem to almost magically disappear, all on their own…

This shortened polishing process seems to have worked quite nicely. Time spent carefully prepping the body seems to have paid off. Nitro finishing seems to be a skill which takes a fair bit of practice – but a careful approach seems to be the key to excellent results. With each job I seem to be able to apply thinner and thinner lacquer loads, with fewer and fewer obvious faults.

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