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Lacquer Bubbles In Progress


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I'm close to finishing #1. Many more to come.

Can anyone help me troubleshoot the best way to get rid of...

1. Two large drops of lacquer?

DSC00603.jpg

2. Multiple tiny bubbles that have very little weight to them. For some reason, these are only on the sides of the body.

DSC00609.jpg

So far, I've sprayed 6 total coats of Stewmac's aerosol nitro. The first was a light dusting, the last 5 were progressively wetter. I have done no sanding, only clean wipe downs to move dust etc...

I think I have about 4-6 coats left to put on, which brings me to another question: When do you know you've done enough lacquering to cure and buff?

Thanks very much,

CT

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I'm close to finishing #1. Many more to come.

Can anyone help me troubleshoot the best way to get rid of...

1. Two large drops of lacquer?

DSC00603.jpg

2. Multiple tiny bubbles that have very little weight to them. For some reason, these are only on the sides of the body.

DSC00609.jpg

So far, I've sprayed 6 total coats of Stewmac's aerosol nitro. The first was a light dusting, the last 5 were progressively wetter. I have done no sanding, only clean wipe downs to move dust etc...

I think I have about 4-6 coats left to put on, which brings me to another question: When do you know you've done enough lacquering to cure and buff?

Thanks very much,

CT

To remove the laquer drips, take a 2"x2" piece of 320 grit and roll it into a tube. Hold the sandpaper roll in the center of the tube and use the end to sand the drip lightly until you remove it. Then you can go ahead and level the rest.

As for the air bubbles, two things will cause this. Either you shot the coats too heavy, or you didn`t leave enough time between coats to flash off. Keep in mind that the higher the humidity, thinner coats and more flash time between coats are required. Being that you have laquer drips suggests that you shot the coats too heavy.

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Thanks for the info.

Do you think the finish is beyond repair?

Hard to tell from the picture, but it looks like the air was in the the second to last coat. First, try to sand them out with 320.

If you can`t get them out, take naptha on a soft rag and wipe the sanding dust completely out of the holes. Then use Stew-mac

clear grain filler to fill the holes, then shoot your next round of clearcoats.

Good luck

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On the sides of the body, I don't see any bubbles on the maple (is this correct? or just a photo effect?). This would lead me to suspect that you didn't seal the grain on the mahogany and that you have some air coming out from the endgrain pores.

...if that is mahogany.

Edited by erikbojerik
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On the sides of the body, I don't see any bubbles on the maple (is this correct? or just a photo effect?). This would lead me to suspect that you didn't seal the grain on the mahogany and that you have some air coming out from the endgrain pores.

...if that is mahogany.

It is mahog. I did seal it, but it didn't really seem to take on the edges b/c of the grain. That's probably what it is.

As an update, I just scuff sanded with 400 grit and wiped clean with Naptha. Then I sprayed coat #7 and they almost immediately came back.

Can I continue to sand them off and expect them to come back every time? What effect would the buffing have?

I don't want a bubbly guitar :D Hopefully it's a correctable problem

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Am I right that you're not getting the bubbles on the maple?

I would think that eventually the pores will get filled with lacquer, but it could take you many many coats. Rattle can lacquer has more thinner in it than regular lacquer, so it generally goes on thinner...and if you shoot a real thick wet coat, the evaporation of the solvent can also cause bubbling (but then I'd expect bubbles on the maple as well).

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Am I right that you're not getting the bubbles on the maple?

I would think that eventually the pores will get filled with lacquer, but it could take you many many coats. Rattle can lacquer has more thinner in it than regular lacquer, so it generally goes on thinner...and if you shoot a real thick wet coat, the evaporation of the solvent can also cause bubbling (but then I'd expect bubbles on the maple as well).

There are some bubbles on the maple, but it is definitely a different cause.. a run built up witha few bubbles. The bubbles on the mahogany are almost uniform in that they pretty much cover the entire side wall of the guitar.

That being said, the back is coating beautifully, and the maple top looks unreal.

Should I sand the sides (or entire body) before each new coat? If so, does that mean I'm down to one coat per day?

Thanks for your help Erik.

Edited by ctelep
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sand/ wet sand with 400 gril and spray more coats and your grain will fill in

Yep. :D

Well, I just did #9 and the bubbles are back.

What happens if the build is ready for buffing and the bubbles still show? Will they buff out at all?

As a side note, I built this guitar to be played well, not looked at. It just happens that the guitar looks great too. I'm not going to be depressed if there are burps in the finish, because it's really going to sound great and will still look great too...i.e.no one is ever buying this guitar. Maybe I'll give it to my kid someday, maybe.

DSC00600.jpg

DSC00601.jpg

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Fan? You very likely have too much heat / airflow over the surface and / or laying it on too thick. The lacquer skins over fast and can't gas off properly, hence the gaseous solvent bubbles trapped inside. I've had it happen to me bigtime when leaving a black guitar outside in the sun for 1/2 hour before shooting clearcoats. They weren't just bubbles , they were blisters. Solution : stop using the fan.

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Unbelievable. The bubbles only pop out on the side of the guitar closest to the fan.

The fan was not a factor in my calculations.... :D

...but yeah, I'd leave it away from the fan for the last few coats and see if they disappear.

BTW, with nitro I wouldn't think about buffing out for 3-4 weeks. Seriously. Nitro needs time to cure properly.

Hang it in a ventilated area and sniff it once a week. When you can't smell it anymore, find an inconspicuous place (pickup cavity, whatever) and see if you can dent the finish with your fingernail. If you can't, then buff away.

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No garage?

If letting it cure in the house is your only option, I'd crank the fan and live (an extra 10 years) with the bubbles.

Yeah, move it away from the fan a bit and see what happens. Alot of finishing is like that (try it and see what happens).

The room actually has two windows, so I moved the fan into the other window and kept the booth in tact.

NO BUBBLES!

Solved.

When do you know enough lacquer is enough? 12 coats?

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No garage?

If letting it cure in the house is your only option, I'd crank the fan and live (an extra 10 years) with the bubbles.

Yeah, move it away from the fan a bit and see what happens. Alot of finishing is like that (try it and see what happens).

The room actually has two windows, so I moved the fan into the other window and kept the booth in tact.

NO BUBBLES!

Solved.

When do you know enough lacquer is enough? 12 coats?

When it's enough. I tend to shoot about 7 to 9 of waterbased clear or nitro. You can get away with 6 if you can avoid levelling/it goes on smoothly enough, or if you shoot high-solids stuff like polyester, 2 or 3 will be more than enough.

12 coats can be a little heavy, but it's a safe option if you're not quite familiar with your materials, and want to have some leeway when levelling and buffing.

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