Bubbles in Paint

[ThreeChordWonder]

I'm trying to paint a guitar body, but I keep getting bubbles in the dried paint. Solvent based rattle cans, not nitro.

Is this simply because I'm putting it on too thickly or could there be another reason?

Thanks in advance.

 

[Chris Pile]

Most spray can finishes are mixed with a pretty hot solvent which boils off too quickly, making bubbles.

 

[PFDarkside]

I’m just getting started on my paint journey so others will know far more than me….

The things I think of immediately are a contaminant between coats (did you clean with wax and grease remover before shooting) a paint incompatibility or maybe a layer of paint not adhering. (If it’s not lacquer, did you scuff between coats if it was fully dry?)

What are each of the paints you are using? (Primer, bases, any transparent and clears?)

 

[GuitarStv]

Make sure you're spraying very lightly and allowing everything to dry properly between. Multiple light coats will lead to a much better finish than fewer thick coats.

 

[PFDarkside]

Make sure you're spraying very lightly and allowing everything to dry properly between. Multiple light coats will lead to a much better finish than fewer thick coats.

Yes, good point. The can will tell you time to recoat, it’ll be something like less than an hour or over 24 hours.

 

[GuitarDoc]

I'm trying to paint a guitar body, but I keep getting bubbles in the dried paint. Solvent based rattle cans, not nitro.

Is this simply because I'm putting it on too thickly or could there be another reason?

Thanks in advance.

Are they actual "bubbles" (air/gas filled that pop as they dry)? Or are they blobs of paint?

 

[ThreeChordWonder]

I’m just getting started on my paint journey so others will know far more than me….

The things I think of immediately are a contaminant between coats (did you clean with wax and grease remover before shooting) a paint incompatibility or maybe a layer of paint not adhering. (If it’s not lacquer, did you scuff between coats if it was fully dry?)

What are each of the paints you are using? (Primer, bases, any transparent and clears?)

I've been using Rustoleum glass lacquer.

I usually left it at least an hour between coats,. Overnight for the final coats. It didnt matter whether I sanded between coats or not.. The wood was sealed with sanding sealer first.

 

[Securb]

I am curious what the sealer was. Many paint products/brands do not play well with each other. I use auto primer, sprayed very dry in several coats. I then wet sand and clean the guitar with Prepsol before applying the paint. If you are spraying light that is a good start. If there is wax and grease in the finish you will get what is called "fish eyes" which are typically larger bubbles. Using a cleaner between products like Prepsol is a good practice to avoid fish eyes. It doesn't sound like this is the problem.

Tiny bubbles could be caused by many factors. Dust, temperature, and conflicting products can be factors. Spraying too thick can also cause bubbles but it seems like you are not going too thick.

Also, when spraying, make sure you are spraying past the guitar. Do not stop at the edge of the instrument this can cause build-up on the edges and more bubbles. Continue a steady path a few inches beyond the guitar.

 

[ThreeChordWonder]

^ Doing all of the above.

I'm baffled. It's also cost me a fortune in paint and sandpaper.

I'm about to strip the thing - again - and this time just go with a woodstain and clear poly.

 

[Chris Pile]

Strip the finish chemically - don't sand it off.

 

[ThreeChordWonder]

Why not?

 

[Securb]

Why not?

You chance removing more wood sanding the guitar again. Or making the surface uneven.

 

[Chris Pile]

You chance removing more wood sanding the guitar again. Or making the surface uneven.

Exactly. The wood is already sanded (or should be). Chemically stripping the finish will remove any funkiness that may have caused bubbling of the finish, or any other troubles. Sanding will ALWAYS leave some finish behind, unless you sand it all back to clean wood. If you make sawdust - you went too far.

When I strip any finish, I remove the dissolved gunk with a plastic scraper (old plastic credit or gift cards work great). I then clean the whole surface with lacquer thinner or acetone using a light gray or white Scotchbrite pad, and finally a lintless wiper or cotton rag. Let it dry, rub it smooth with freshly washed hands. You'll feel any sticky places that still need cleaning, or raised fibers. Blow it all off with compressed air. Hang and let air dry for at least a couple hours - overnight is best. That gives any solvent time to outgas before you then stain or shoot sealer.

 

[ThreeChordWonder]

I find dealing with the goop left by paint stripper whose than sanding. And by using a relatively large orbital sander on the flat bits to sand just until I just see the wood I don't create divots.

I'm also concerned about old paint and stripper that's soaked into the grain.

Each to his own I suppose.

 

[dave74]

 

[ThreeChordWonder]

Michael Jackson' fave, allegedly:


https://youtu.be/hfvegiuYHB4

 

[GuitarDoc]

Definitely DON"T use chemical paint stripper! That makes a horrible mess and leaves a residue that needs to be thoroughly rinsed off with water. With water...water on wood! Just asking for more problems. And since you've been using lacquer, there's absolutely no need for a stripper.

I've been doing this (finishing and refinishing with lacquer) for many years and can definitely help you to get a perfect finish, but I need to know a couple things first...
1. are you using solid color finish?
2. solid color covered with clear?
3. stain covered with clear?
4. Are they really bubbles or are they spots/spatters of paint/clear?

It's not hard to fix your problem, but the solution will be different for each of the conditions I'm asking about.

I'll get you up and running (playing) as quickly and efficiently as possible. It IS possible to get excellent results with rattle cans...sometimes as good as with the best spray equipment, so take heart.

In the meantime, there is a series of 3 videos on StewMac that actually are very good that take you thru the entire project. They are lengthy but there's good info in them for beginner AND pro. I've been doing this from before these guys were even born, but even I picked up some good tips.

https://www.stewmac.com/video-and-i...inish-repair/aerosol-guitar-finishing-course/

 

[Securb]

Definitely DON"T use chemical paint stripper!

That is exactly what I used on this guitar and the finish seems to have come out fine. I think we have to agree that different people have different processes for getting things done that yield great results. I do not think there is a wrong or right process here just many different approaches.

 

[Chris Pile]

Definitely DON"T use chemical paint stripper! That makes a horrible mess and leaves a residue that needs to be thoroughly rinsed off with water. With water...water on wood!

Chemical strippers are NOT rinsed off with water. Where the hell do you keep coming up with this crap?

 

[GuitarDoc]

Chemical strippers are NOT rinsed off with water. Where the hell do you keep coming up with this crap?

You mean that "the ones you've used" are not rinsed off with water.

Well, I suppose it depends which stripper you use. I've used several different strippers before and have always used paint thinner to rise off the mess, but there are some that specifically instruct to use water. My statement was based on making sure he avoided those.