Explanation of why this happened...

J

JayL

Hey all,

I have a quick question (I hope)

As some of you may know I have been working on a Guitar. First time using Automotive paint.

My screw ups are becoming fewer and when they happen they seem to be getting smaller. (Both good things)

I had a few areas where the paint did not lay perfectly smooth or there were runs so I sanded them back to either the black base coat or to the primer. I had 2 spots that went all FUBAR on me and I don't understand why and was hoping someone with much more knowledge than I could explain to me what happened.

Example 1 - Small.jpg

Example 2 - Small.jpg

Example 3 - Small.jpg

Entire Process:
Sanded off old paint.
Sealed with wood sealer.
Sanded smooth.
Primed with rattle can auto primer. (I know this crappy but it was all I had.)
Sanded smooth.
Black Base coat. (SPI Intercoat mixed with Carbon Jet Black pigment.)
Sanded smooth.
Front - Painted with a metallic blue. (SPI Intercoat mixed with mica and blue pigment.)
Sanded smooth.
Sides and back - Painted with a Darker blue. (SPI Intercoat mixed with mica and blue pigment.)
Sanded smooth.
Front Burst - First Black and then over with the same Dark blue on the back.
Sanded smooth.

So the areas that had issues were ever I sanded down to in the above steps, I would redo from that step down. (If that makes sense)

I am just not sure why the above shyte happened and any assistance will be greatly appreciated.

Thanks again
JayL
Tampa, FL
 
If I were to guess, I'd say the rattle can auto primer is the culprit. Also, I believe you are always supposed to spray another coat of base if you sand it down, aside from de-nibbing and the like.

I'm sure someone else will jump in and help out as well. I would never use the rattle can primer, if it's all you have then don't use it. Order some real primer and wait, or go to a local body shop and get some. But that's me.
 
The spots that are bad are areas that it looks were heavy with the wood sealer or the primer.

I know its quickest to blame the rattle can primer, but the only place it happened was in areas that were probably just too heavy. the whole rest of the job didnt have an issue with the primer. A little pocket area, bottom edge are spots that would allow it to pool up.

We had this kind of issue happen to us when we used the bondo red spot putty. Watched it wrinkle up any paint we tried to put on top of it. This was a last step, working between the embossed letters of the Jeep. Pretty sure that spot putty is a lacquer based system. Odds are a rattle can is gonna be a lacquer.
 
Thanks for all the reply's folks.

I have sanded back the problem areas and will be trying again.

The part that still confuses me is if its the primer or sealer that is causing it, why is it not happening until I am on my like 3rd or 4th layer of paint? (Black base, metallic blue, black and then the dark blue is showing the lifting but only on its last covering)

I don't remember which of the forum members signature says it but the comment "It's not custom painting it's custom sanding" has been so true with this project.

I think I am getting better at removing paint than I am at laying it down. In fact maybe I'll make that my signature. ;)

Thanks again.
 
Possibly the solvent build up between all the layers? Maybe when you are sanding it is releasing some solvents that were trapped and then messing with the next layer?

Almost impossible to say without having seen every step, even then it's hard to say.
 
Thanks Mitch,

I was wondering about that. I am very careful to let each layer dry over night before going on to the next unless I am doing the airbrush burst work. I did do the black and then the dark blue so I suppose it is a good possibility that the solvents built up.

No worries. Well at least not now. I was cursing like a sailor when it happened.
 
looks like lifting to me. I didn't catch what you all did, what was used and how you proceded to repair. But if you are saying you sanded through the clearcoat in areas down to base. then resprayed base, lifting would make sense. Solvent from your new coat will get under that thin edge of clear where it was cut through all the time and lift the area. In cases like that carefully spraying some epoxy primer (not going too heavy) over the area then spot in some base and then reclear is usually the best way to go.
 
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