First DIY re-spray. Questions about clear-coating.

[Tony Ounsworth]

Morning all.

I had a Squier Strat knocking around which cost me £40. It was ok, I'd already upgraded it quite a bit, but the sunburst finish was very "boiled sweet" and the joins in the body wood were very unsubtle (especially under the jack plate). No interesting wood grain visible, just a pretty cheap finish, as you might expect.



So I decided to have a crack at sanding and re-spraying the body, using acrylic car paint and acrylic clear gloss lacquer. I haven't got a garage or anything like that, but I do have a small outside cupboard which I rigged up as follows:



The bungee cords are quite handy, as I can easily spin the body. Anyway, long story short the grey primer went on fine, and then I moved on to the metallic colour coat (Aquamarine Frost, a blue/green Ford colour). This I did with the body flat in a large plastic box, as I understand the flakes need to "flop" in different directions to reflect the light and give the metallic effect you're after.




This also went well, although I was learning from my mistakes along the way. Had to stop and sand various runs, remove dust etc, but in the end I was actually pretty stoked with the results.






This is the guitar mocked up with no clear coating yet applied:






What happened next was I went backwards! I applied a few coats of clear acrylic lacquer, then like an idiot tried to flick a hair off the body. Of course it made a mess. Tried to remove the mess. Made a bigger mess. Left fingerprints. Argh!

So I wasted a whole weekend waiting for it to dry, then wet sanding the mistakes out, then re-spraying the sand-throughs, until finally on Sunday I was ready to re-start the clear coating.

Which brings me to my questions:

1) I've done about 6 coats of clear acrylic lacquer now. How many in total should I apply? I haven't touched the body at all other than to wipe it down with a tack cloth each day before putting new coats on
2) The can says to let the clear coat harden for two weeks. How accurate is this?
3) Most importantly, any tips for sanding/polishing the coat to a high gloss finish? I was planning on starting at 1,200 grit, then up to a 3,000 grit polishing cloth, but I also have some rubbing compound. What's a good plan for doing this?

It's a fairly low-risk endeavour, so it doesn't matter if I mess it up, but it's going well so far and I'd like that to continue!

 

[Day-mun]

Acrylic lacquer seems to polish up pretty easily; I did a neck (using Deft brand) and just lightly buffed with a Mr. Clean magic eraser, then a scrap of an old bath towel. Formby's makes some good stuff for buffing (-used the swirl remover), -But do be sure to let it cure completely. I'd go longer than the back of the can tells ya if the piece still smells like solvent. -If it is still de-gassing and letting off the carrier, it ain't done doing what it is doing... I'd leave it alone.

 

[Tony Ounsworth]

Yeah, I was thinking I might leave it slightly longer. I'm on holiday for a week from Sunday, so at least I can't fiddle with it while I'm away!

 

[Day-mun]

-Looking really good so far! -Enjoy your trip!  ccasion14:

 

[Tony Ounsworth]

Thanks! It's not looking bad at all is it? I'd sort of assumed it wasn't possible to get a good finish, but so far so good!

 

[stubhead]

I consider the nose test to be definitive, more so that any directions of the can - they might have a reason for wanting you to think it'll be done in a week, hmm? And the difference in how all these things act in different humidity and temperature is amazing, it's like different products sometimes. But then again, I'm getting over the notion that you shouldn't "trust" a good finish that goes on easy and looks and acts... good. All the kids in the white coats messing around with sub-molecular nucleo-twaddingery stuff are working miracles in every other field, why not spray-on lacquer? Just the past ten years, simple things like "sandpaper" and "rubber" are qualitatively different.

 

[Tony Ounsworth]

I shall trust my nose then!

I don't know why I expected it not to work somehow, but after all you're just spraying a piece of wood.

 

[DarkPenguin]

Lovely work so far.  That color looks much better on a guitar than a ford.

 

[Tony Ounsworth]

Well, things have changed a bit. I managed to get a huge run in the clear coat as I got carried away spraying too close. I then panicked and handled it too soon, and well...long story short I had to let it dry and sand it back almost to the primer.

So I took the opportunity to have a rethink. I originally bought two colours, the Aquamarine Frost already shown, and another colour called Blue Lagoon which is very similar to Ice Blue Metallic. Anyway, I tested that colour on a block of wood, and I much preferred it, so I changed to that!

Glad I did:











Really pleased with the results this time, I don't think I've got a single visible blemish on the front of the guitar, and the metallic colour really shimmers in the light. The back has got a couple of tiny specks on it but nothing to worry about. I've done a couple of clear coats and will keep doing a couple every night for the rest of this week I think.

I really hope I don't mess it up again, as for now I'm back to thinking it's going well and worth doing.

 

[Cagey]

That came out really well! Nice job!

 

[Tony Ounsworth]

Thanks. Still plenty of opportunities to mess it up though! I'm nervous about the clear coats now after it went so wrong last time. I must remember not to panic if something gets stuck in it, and to let it dry before carefully sanding it out.

 

[Cagey]

I must remember not to panic if something gets stuck in it, and to let it dry before carefully sanding it out.

Exactly. And be gentle about it. You're looking at 8 to 12 coats of clear to do it right, so even if the first "repair" isn't perfect, as you go along coating and level sanding between coats, it will eventually disappear. Then you finish with a wet sand progressing about 200 grit at a time up to about 1500 or 2000 grit, rubbing compound finally, then polish. It'll be gorgeous.

 

[Tony Ounsworth]

So should I be sanding between clear coats? I've been following the Re-Ranch guide, and it says to shoot 4 clear coats to protect the finish initially (and dusted on at that, to stop the metallic flakes flattening). If so, what grit should I be sanding with between coats?

 

[Day-mun]

I'd go with the initial four coats to get a good base goin' before sanding; I use 600-grit between coats (on poly), but even then, I don't sand between every coat... but ya should wait for the experts to comment. -Don't just go with my two-cents.

 

[Tony Ounsworth]

600 seems quite coarse to me when I've used it. I'd be scared of going right through to the paint! It's only acrylic lacquer, i.e. water-based.

 

[Cagey]

Several coats to get a base going is a good idea, but I sand between every coat after that. Also, I use 320 grit.

The trick is to use a hard rubber block to back the sandpaper for the flat surfaces, get it wet, stay away from the edges, and go slow. There's a reason a good lacquer finish costs a lotta money and OEMs don't usually do them - it's very time-consuming. You need to be patient. Trying to get ahead of the game time-wise is a recipe for disaster.

The edges will almost sand themselves. Do them by hand, just a little bit at a time. The smaller contact area means there's a lot more pressure at those points than you might think, which makes it very easy to sand through. Keep a rag damp with naphtha and just give the edge a few rubs with the sandpaper, wipe it with the rag, and have a look. You'll be surprised how fast the edges will get smooth.

I don't try to get it perfect in the early coats. It's a gradual build-up. As you go, the valleys will fill and it'll get easier to level the thing.

Once you've got 8 to 12 coats on the thing, you're ready to finish sand. I start with 600 grit, then progress through 800, 1000, 1200, 1500, and maybe 2000. Rub it out with compound, then polish, and you're golden.

 

[Cagey]

You might also want to mask off the sidewalls in the neck pocket. Warmoth's neck-to-pocket fit is very nearly a press-fit, and lacquer chips very easily. If you have any finish overhang in the pocket, you're liable to chip it installing the neck. Alternatively, you can sand the pocket sides once the finish is cured, but I have an aversion to having any sandpaper near a finished product. Seems like an accident waiting to happen.

 

[Tony Ounsworth]

Thanks Cagey.

Yes, I was wondering about the neck pocket. It's full of paint at present, and I was indeed planning to sand it a bit at least.

320 grit between coats, really? That seems very coarse! I think I used 240 grit on the original body to key the surface. I can't help thinking that I'll simply tear through the clear coat with 320 grit...

 

[Day-mun]

I had a feeling my 600 was too fine for the betweeners... but I had about the same reaction to the thought of 320 as you did to my suggestion "-Geez! That seems pretty rough! I wanna put the paint on, not take it off!"

Trust the man! The products of his labors speak on his behalf from every picture posted in his threads.

 

[Cagey]

Thing is, if you sand it too fine, the subsequent finish won't adhere. Nothing to bite into. 320 sounds coarse, but it's not. You're only trying to get the high points off the finish, not remove the finish. That's why you go slow, so you can see the effect you're having and stop when you get there. Also, the hard rubber backing block is important, lest you sand waves into the thing. You're trying to level the surface, that's all. As you add coats, the valleys will fill in and eventually the whole thing ends up very flat. Going through the progressively finer papers at that point usually doesn't remove much, it's mainly to take progressively finer scratches out. Once they're all gone and you buff/polish it, it'll look like wet glass.

Incidentally, when I say "slow", I don't mean moving slowly as much as I mean sanding in small increments. Give it a few rubs, see what it looks like. Keep doing that until get is levelled out. You don't want to take too much finish off - just the high spots of the "orange peel" effect that the spraying has. If you were brushing it on, you'd be trying to level out the brush marks. You'll eventually get a feel for it.