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Old 06-29-2011, 03:41 PM
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I'm getting small bubbles/specs when I spray Clear Coat

Ok so I need help figuring out what I'm doing wrong. I'm a newbie to painting, this is my 3rd car, but I upgraded my gun, compressor, and so on and now I'm getting what appear to be small bubbles in my clear coat. I'll give you a run down of everything I'm using and hopefully someone has some advice.
Ok here goes, I'm using a Asturo AOM HVLP gun with a 1.3 tip and spraying my clear coat at around 27psi. I use a small water filter at the gun and psi gauge. The CFM recommendation is 6 for this gun and my compressor goes up to 9 so that shouldnt be a problem although it does kick on after 1 min of continuos spraying. I'm also spraying a universal clear with a medium hardener over dupont paint and lacquer primer. My clear to hardener ratio was 4:1, I'm overlapping 50% and I was spraying at 75 degrees. Also I'm in a garage, dont have a paint booth. Now here is where it gets weird, when I sprayed the front of the car the bubbles or whatever you want to call them appeared all over right away, but when i sprayed the back of the car, where there was less wind there seemed to be no bubbles.. So maybe the wind played a factor in it or perhaps I was laying it on too thick or maybe I need a better filter?? Can i just sand the car with 1500 grit and hope they go away? What do you think
John

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Old 06-29-2011, 03:55 PM
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[QUOTE=jfaur]Ok so I need help figuring out what I'm doing wrong. I'm a newbie to painting, this is my 3rd car, but I upgraded my gun, compressor, and so on and now I'm getting what appear to be small bubbles in my clear coat. I'll give you a run down of everything I'm using and hopefully someone has some advice.
Ok here goes, I'm using a Asturo AOM HVLP gun with a 1.3 tip and spraying my clear coat at around 27psi. I use a small water filter at the gun and psi gauge. The CFM recommendation is 6 for this gun and my compressor goes up to 9 so that shouldnt be a problem although it does kick on after 1 min of continuos spraying. I'm also spraying a universal clear with a medium hardener over dupont paint and lacquer primer. My clear to hardener ratio was 4:1, I'm overlapping 50% and I was spraying at 75 degrees. Also I'm in a garage, dont have a paint booth. Now here is where it gets weird, when I sprayed the front of the car the bubbles or whatever you want to call them appeared all over right away, but when i sprayed the back of the car, where there was less wind there seemed to be no bubbles.. So maybe the wind played a factor in it or perhaps I was laying it on too thick or maybe I need a better filter?? Can i just sand the car with 1500 grit and hope they go away? What do you think
John[/QUOT

let me guess Epoxy primer and a cheap Putty on topp to cover small pores or holes??
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Old 06-29-2011, 04:30 PM
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you are rushing it . give it more flash time between coats. and there is nothing wrong with epoxy .


but why did you use lacquer primer. it is worthless. especially if it is duplicolor.
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Old 06-29-2011, 08:08 PM
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give longer flash time and i have found water based primer sands like chalk it is great. Make sure it is water based and not part water. It is hard to find. You may be to heavy on you coats. If you have water coming in the lines it will also cause a problem.
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Old 06-29-2011, 11:15 PM
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Quote:
Originally Posted by shine
you are rushing it . give it more flash time between coats. and there is nothing wrong with epoxy .


but why did you use lacquer primer. it is worthless. especially if it is duplicolor.
there is allot of real bad epoxy colors! anda lott of putty types that wont cure when put down straight on epoxy colors and when you put a base or solid on it it will rise up in form of bubbles!
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Old 06-30-2011, 04:58 AM
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dont know what you have there but i use a quality epoxy primer . it is all i use. no other primers . small bubbles is solvent pop. unless you have introduced acid into the job then you have co2 bubbles .
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Old 06-30-2011, 06:17 AM
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If the bubbles are only in the clear it sounds like you applied it to thick,and the top layer dried trapping the solvents ,causing solvent pop ...since your outside The metal could be too hot or the sun can cause the same thing........
How fast did the clear dry? were using extra slow hardner here in Ga. ..What brand of clear was it,that may be playing a part also.
Your base could also cause this if you cleared before it was ready.
BTW,
If it was an (improperly prepared) acid problem the bubbles would be way down between the metal and the primer ,not suspended in the clear....
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Old 06-30-2011, 06:58 AM
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I would guess you're spraying too thick. So if it flows out with a thinner coat (i.e. less material flow), that would be the way to go assuming that you're getting solvent pop from spraying too thick a coat. If it won't flow out when you back the material flow down, you need to reduce some with the proper reducer.
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Old 06-30-2011, 10:59 AM
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ok so when i spray, should i just do one pass then wait 30 min or is it ok to spray 2-3 times over one area real quick then wait 30 min? The Clear I used was DynaTone Formula 77 PC-100 2.1 VOC and the hardener was DynaTone Formula 77 Medium. The reducer I used with my base was Zero VOC Reducer Medium 7780. So the Clear and Hardener were from the same company but my base and reducer were not, does that matter?? Also It wasn't sunny when i sprayed, I was in the garage but the door was open and it was kinda windy. It almost seemed like the plastic bumper did not have this problem as much as the metal..
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Old 06-30-2011, 11:07 AM
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oh also I almost forgot to mention that I sprayed a Acrylic Lacquer Primer Surfacer and mixed it 1:1 with Acetone. Ive heard Urethane Primer is better..?
I didnt cover the whole part of the car I painted with primer though, just the parts where i had body filler. The filler i used was Rage Extreme, and the spot putty was made by Bondo.
Hope to hear more good advice from you guys, your all very helpful and I really appreciate the time you take to help me out
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Old 06-30-2011, 05:04 PM
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Well ,Your choice of materials wasnt that great and will most likly give you other problems later on but.did you wipe it down with wax & grease remover and did you tack it? It almost sounds like your tip is too small and you have to pile it on to get it wet or mabey you used the same gun for the primer and base and now the gun is plugged up try taking the gun apart and give it a good cleaning.you should spray clear just like you want it to look but in one pass and overlaop about 50% (the edge of your fan should go half way into the previous pass) something else it could be is water or oil contamination in the air supply ,filters can cure that.It might even be something completely unrelated to you ,I've seen a guy have similar problems in an industrial park where someone was doing something and the wind carried it over to his shop causing almost the same trouble..furnace filters in the door opening cured it for him.Heres what I would do, check out the gun and the air supply put a 2x2 frame with filters framed in 2-4 should do it.The frame only has to be about 24" high so yo raise the door and set it on the frame,seal the top of the door with old blankets (when you lift the door there will be a gap at the top where it pulls away from the wall)then try painting an old fender to see how its working...if its working dry sand the car with 600 on your da scuff and prep and reshoot the clear,but reshoot it first thing in the morning when its cooler and theres not much dust flying around outside.....having a pro painter come over and look at it would be best ,he could tell you at a glance what the problem is.If your still having trouble maybe you should concider getting another brand of clear.
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Old 06-30-2011, 05:10 PM
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bubble problem

did you use a sealer and did you wax and grease it before you sprayed your base coat
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Old 06-30-2011, 05:20 PM
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Hey 48, wazup???
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Old 06-30-2011, 06:55 PM
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yeah i used a wax and grease remover before i sprayed the primer. I just used a tack cloth afterwards because i didnt want to get the primer wet since its a Lacquer, ive heard getting this type of primer wet can turn it to mud. is that true? should i have used wax and grease remover after each coat of paint? Im thinking about using SPI primer and clear next time, they sound pretty good.
Thanks again for your advice guys!
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Old 07-01-2011, 05:59 AM
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In your original post, you mentioned the front of the car had bubbles and the rear didn't. You also mentioned "no wind" when you sprayed the rear. IMHO there is your answer. The wind caused the front to skim over trapping solvents and causing bubbles or solvent pops. I don't claim to be a pro but I do have a nice home-made spray booth with exhaust fan and front to rear air movement. I never turn on the fan until I'm done spraying the clear (each coat) and then only long enough to evacuate the booth, then the fan is off.

I use SPI clears and I cannot speak to the other brands of clears, but if I were using PPG, Dupont, or? I would use the same approach. In addition I always give myself a little extra flash time between coats, more is better than not enough.

Other posters have commented on other issues you may have and I cannot speak to those, but solvent pops can be difficuly to fix especially if you have many of them. If you applied three coats, the pops likely occured from solvent in the first coat so you may have a crator all the way to the first coat. Depending on how much film build you have in the clear, I would sand with a hard block and 1000 grit wet, roll it outside in the sun for 6 or 8 hours, then apply two more coats of clear.

Solvent pops are a pain in the ***

Jim
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