Paint Defect

TrevorR

New member
Hi Guys,

I am fairly new to spray painting and i have come across an issue that i am unfamiliar with. Me and a mate were painting his car to repair a big section of his bonnet that was scratched (the scratches went all they way back to the bare metal) so around the repair we took the surface back to bare metal then filled the scratches and sanded, then put a layer of spray putty over the area then sanded then etch primed before using a final primer surfacer then gave that a wet sand with 800g. We scuffed the remainder of the bonnet and then put down three coats of basecoat, this all went fine however when it come to the clear things seem to have gone horribly wrong.

We put down 4 coats of clear, waiting the time that was on the can (10 minutes) for flash off between each coat. However in the finished job there are defects i have not seen before. See picture attached.

paint defect.jpg

I have tried to wet sand and buff out this defect with no luck. So at this point i am thinking i could be something to do with the two clear coat systems reacting badly with each other but i really have no clue.

I should mention the defect is only noticeable on the area of the bonnet that was not taken back to bare metal.

Info about the job
  • We used Acrylic paints for this job.
  • Air Compressor is a Lincoln 2.5hp with 380L/min free air delivery
  • Spray Gun is a KC tools Gun, 2.0mm tip was used (GUn consumes 285L/min @35psi)
  • Air Line Setup: There is a water trap on the compressor before the outlet, then on the other end of the hose i have a water trap followed by a pressure regulator and then the gun.
  • Temp on the day was around 26 degrees Celsius

My thoughts are to now remove the bonnet from the car, strip all the paint off the bonnet and start from bare metal.

Any thoughts?
 

TAZ

Administrator
From what I see, it possibly could be moisture in your lines. This really wouldn't show up on your primer or basecoat, but it will on the clearcoat.
2.5hp is a small compressor to us
Were you working the compressor hard?
Do you have filter(s) on the compressor and gun?

OR, did you wipe the basecoat or primer with anything before going to the next step?

Is the whole hood / bonnet like this or just the area that you took down to metal?
 

TrevorR

New member
Hi Taz,

Nope, the compressor was not working hard at all. it cycle was approx. 30-40 seconds on then 2-3 minutes off.

Yes, on this particular set up there were 2 moisture filters. One just before the gun, and one just at the outlet on the compressor.

The primer was wet sanded with 800g before going to the basecoat stage, the surface was wiped off with a lint free microfiber cloth and some fresh (Distilled) water and dried with a second microfiber lint free cloth. there was no need to wipe the surface between basecoat and clear.

No the part of the hood that was taken back to bare metal is defect free. The only areas that are defective are those that still had the factory 2k paint on it.

Cheers:)
 

TAZ

Administrator
Looks like in the pic that you supplied that those are spray can areas. You can see two of the passes you or someone did. Or that is a extremely narrow gun pattern.
Possibly one of the primers you used was spray canned?
 

TrevorR

New member
Hey Taz,

So i took the car to the local Paint shop and asked them to have a look. They said this was caused by two things

  1. The fan setting used on the gun was too narrow and
  2. The clear coat was applied to thick too quickly. This caused it to react with the solvents in the 2k factory paint resulting in the defect we got.
Thank you for your help with this issue (y)🙂
 

TAZ

Administrator
I think the picture must have thrown me off. I thought I was seeing some cloudiness in the clearcoat
Glad you got it figured out. Good luck in the future
 
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