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How To Prepare Already Finished Body For Repainting?


stratoskier
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Hi,

I'm having a body shop repaint an old sunburst Ibanez body in surf green. The body is actually in very good shape, but there are a few small dents I should probably fill before dropping it off. After reading old posts, I've decided to leave the old finish and just have them paint right over the old clear coat. But I'm assuming I should still sand the old clear and was wondering what grit to use. Also, I'm wondering what type of product I should use to fill the small imperfections with. I have some wood filler, but I'm wondering if I need to sand down to raw wood before applying the filler. It seems like if there's old paint+clear in the gash, the filler might not bind well.

So to recap my questions:

1) What grit wet/dry for sanding the old clear?

2) How to fill/repair imperfections in the old finish before repainting?

Advice?

Thanks much,

Bert

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Hi,

I'm having a body shop repaint an old sunburst Ibanez body in surf green. The body is actually in very good shape, but there are a few small dents I should probably fill before dropping it off. After reading old posts, I've decided to leave the old finish and just have them paint right over the old clear coat. But I'm assuming I should still sand the old clear and was wondering what grit to use. Also, I'm wondering what type of product I should use to fill the small imperfections with. I have some wood filler, but I'm wondering if I need to sand down to raw wood before applying the filler. It seems like if there's old paint+clear in the gash, the filler might not bind well.

So to recap my questions:

1) What grit wet/dry for sanding the old clear?

2) How to fill/repair imperfections in the old finish before repainting?

Advice?

Thanks much,

Bert

Good body prep is going to determine the final results of your paintjob.

If you found a body shop willing to paint your guitar, consider yourself lucky but don't assume they will do any of the prep work. You have to do this yourself.

Having said that ... a body shop isn't likely to seal the body so leaving the original finish may not be a bad idea.

Hard to say waht grit you should start with without at least seeing pics, but I would work your way up to around 400 just to leave some "tooth" for the paint to stick.

Using a finer grit is likely to cause the paint to chip and flake.

Dents on unfinished wood can sometimes be steamed out, but considering the fact that you're leaving the existing finish, I would maybe use epoxy or even Bondo. Wood filler should be applied to wood, not a finish.

Good luck. :D

Edited by DGW
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Hi,

I'm having a body shop repaint an old sunburst Ibanez body in surf green. The body is actually in very good shape, but there are a few small dents I should probably fill before dropping it off. After reading old posts, I've decided to leave the old finish and just have them paint right over the old clear coat. But I'm assuming I should still sand the old clear and was wondering what grit to use. Also, I'm wondering what type of product I should use to fill the small imperfections with. I have some wood filler, but I'm wondering if I need to sand down to raw wood before applying the filler. It seems like if there's old paint+clear in the gash, the filler might not bind well.

So to recap my questions:

1) What grit wet/dry for sanding the old clear?

2) How to fill/repair imperfections in the old finish before repainting?

Advice?

Thanks much,

Bert

If you rub the guitars finish back with 800 or 1000 grade wet and dry to start with you'll be able to clearly see any minor imperfections in the surface of the guitar. Obviously you're already aware of some of the worse ones, but you'll likely notice more once you've taken the shine off of the surface.

When you've identified the deeper marks, these I would normally fill with Davids Isopon P38 (autobody repair putty) if the guitar was to have a solid colour finish. Once the filler has hardened, rub it down again so that it is again as near smooth as you can possibly get it. Once you think it's all pretty smooth, I'd then apply a primer coat to the guitar. This will serve two purposes, filling many very minor scratches in the guitar that are too small to be filled with filler, but also showing out any imperfections remaining after you're filling/rubbing down. It might be adviseable to get some tins of aerosol primer for this very purpose (but make sure that they are compatible with the paint system your painter is going to use on your guitar).

It can't be stressed enough how essential it is to a really good finish to get the preparation stages as perfect as possible - probably 'THE' most important stage of any repaint/refinish. So time spent at this stage will pay dividends later on, even if it means repeating the rubbing down, filling, rubbing down, priming, rubbing down stages four or five times until the resulting primed body is absolutely perfectly smooth and uniform.

Incidentally, the guy who is going to be painting your guitar for you will think you're the best thing since sliced bread if you hand him a perfectly prepared guitar body..................I know I certainly would!

Jim

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Great - thanks for the tips, guys!

Normally, I wouldn't have thought of having a body shop paint a guitar, but I know this guy a bit and I've seen some other wood paint jobs he's done and they looked very good. Plus, I haven't found any luthiers that paint guitars locally. I'll follow your advice on prepping the body and will check with him to see what primer would be compatible with his paint.

Take care,

Bert

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Great - thanks for the tips, guys!

Normally, I wouldn't have thought of having a body shop paint a guitar, but I know this guy a bit and I've seen some other wood paint jobs he's done and they looked very good. Plus, I haven't found any luthiers that paint guitars locally. I'll follow your advice on prepping the body and will check with him to see what primer would be compatible with his paint.

Take care,

Bert

Have him prime it for you, this guarantees you a compatible primer, and since it's likely a 2k primer a much better than rattle can primer. Then shoot a guide coat.

A guide coat is simply a misted on layer of paint that you use to see low spots when block sanding. Googling block sanding and guide coat will get you more info than you need. But this is how top dollar custom cars and motorcycles are painted.

You can then sand back with his prefered grit to get a level surface. From there then use body filler (bondo for lack of a better term) to fill your low spots and reblock sand. He can probably help you do the filling since he will have a filler of his choice around.

Then its paint and clear. If he's using a system like House of Kolor, there will be a sealer coat as well. You can tint the sealer coat and clear over it.

This is the way that House of Kolor's head tech guy painted a guitar in a class I took from him. People will put down the use of filler, but in very small amounts used correctly it can't be beat for getting a level surface to paint on.

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Great - thanks for the tips, guys!

Normally, I wouldn't have thought of having a body shop paint a guitar, but I know this guy a bit and I've seen some other wood paint jobs he's done and they looked very good. Plus, I haven't found any luthiers that paint guitars locally. I'll follow your advice on prepping the body and will check with him to see what primer would be compatible with his paint.

Take care,

Bert

Bert

In many respects (with the exception of the initial preparation stages when painting from raw wood), the process is very similar between spraying a solid colour finish on a guitar and applying many two pack finishes (basecoat & clearcoat) on, say a car or a motorcycle. The main differences with a guitar body come in the initial preparation stages and the final finishing stages. I know of several very good airbrush artists who work quite regularly on guitars but who don't have their own spraybooths setup for applying their own clearcoat finishes. They regularly take their painted guitar bodies to 'good' car bodyshops to get their finish coats applied. They then simply take their clearcoated bodies and complete the all important final rubbing down and polishing work in house - their finished results are pretty good too.

The main difference between poly guitar finishes and most finishes on your average car is the attention to detail and time taken to ensure that the finish is as thin and as flawless as possible - you wouldn't tend to go over your average car with a jewelers eyepiece checking the finish for flaws, but on a professional, quality guitar finish it needs to stand up to just that kind of scrutiny.

As long as the finish is applied properly and evenly in the sprayshop doing the work for you, it's really then all down to the time taken and the attention to detail during the final rubbing down and polishing stages that will determine the end result - and I don't doubt that in this particular case, that work will be done with the greatest of care. :D

Jim :D

Edited by Foggy
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I would normally fill with Davids Isopon P38 (autobody repair putty) if the guitar was to have a solid colour finish.

Once again, thanks to everyone for all the good advice...

I see that the body filler recommended by Foggy (Davids Isopon P38) appears to be mostly a European product. Can anyone recommend a particular brand of body filler available in the States? I've used good ol' Bondo before and could go with that again. Also, there's a two-part Minwax product that is marketed as a heavy duty wood filler, but it sure feels, smells and behaves like Bondo. I have some of that already, but as DGW noted, I should probably avoid using a wood filler over anything but raw wood.

Cheers,

Bert

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I've heard rumours that Bondo brand will shrink back slightly over time, but have never seen this myself. But I have heard very high praises of the 3M brand of boddy puty and glazes.

For gouges and minor dings, Bondo works just fine.

I wouldn't suggest using it to fill cavities or anything. :D

If you have major fills and/or repairs, I would recommend Marine Epoxy.

It's an adhesive as well as a filler.

It can be sanded, filed, drilled, etc ... and it won't shrink.

Edited by DGW
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Evercoat Gold is the stuff a lot of the pro painters I know like and use. But its as arguable as string brands or Gibson/Fender or Ford/Chevy.

I would go with what the painter your working with likes and uses, if your working with someone stick with his system. You will use so little filler anyways it shouldn't be a big deal to get a little from him.

The key with filler is to use it in very small amounts. Where Bondo gets a bad name is people using it to fill golf ball size dings with out doing the proper work to straighten the metal as much as posible first.

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