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Solvent Pop Issues


DGW
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I've been using urethane for awhile now and I've tried everything from buying traps, different nozzels, different techniques, different temperature rated reducers, and different brand clearcoat altogether ..... NOTHING helps. :D

I'm now thinking of switching to Nitro ...

Is this type of paint more forgiving for solvent pop?

Or will I be faced with the same problems?

Before you suggest "lighter coats" and all the obvious stuff, please know that I've tried EVERYTHING.

Thanks

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Solvent pop is almost always a contaminant.

Have you drained your compressor?

What brand/model number clear?

Are you using it as a complete system?

Are you following the tech sheets to a t?

Where are you located?

Yeah, I've drained my compressor and do so frequently.

I've used Dupont Chroma Clear and a few other cheaper brands.

I'm not sure what you mean by "complete system" ...

I have a compressor, water/oil separator, pressure gauge, and gun.

I do follow the spec sheets every time due to my poor memory. :D

I'm located on the east coast ... yeah, high humidity but I shoot indoors in a climate controlled environment.

Is there something else I need to consider adding to my "system"?

This only happens when shooting clearcoat and only when I wetsand is the solvent pop really apparent (residue gets trapped in the crators).

Pretty frustrating. :D

I was thinking that me and urethane just may not be compatible.

That's why I ask about Nitro.

Would really prefer to stick with urethane, but I need to get this figured out.

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Really really tiny craters, like pin-hole size? Probably your coat is too thick, and skins over before the solvent can get out. Try a thinner coat (although adding a slow reducer often will solve this as well).

If its big craters, it may be that you haven't sealed the grain very well and trapped air is trying to get out. Though that should not happen after the first coat or two.

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syxxstring - I always make sure all the products I use are compatable.

erikbojerik - Really tiny crators ... so tiny that they only show up after I wetsand.

I have discussed this with my local paint distributor and they have pretty much told me the same thing.

So like I said ... I've tried everything.

That's why I'm now looking into shooting nitro.

I've tried different airflow adjustments, different techniques, different products, ... EVERYTHNG I could possibly think of.

I was sorta hoping you guys would tell me it was a contamenent and that I needed a particular trap or filter, but ... I dunno.

Sealer, primer, basecoats always go on smooth with absolutely no problems, but clearcoat is a bitch! :D

It's to the point now that I've stopped painting altogether.

I was just hoping you guys may be able to give me some insight.

As you can probably tell from everything I've already tried, this has been going on for some time now and it really sucks.

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I'm not an expert, but if everything is OK up to clear, one would have to assume that the issue is right there. Have you considered just letting your project sit for an extended time before clear, to make sure there are no curing issues of the color?

And when you say your location is "climate controlled", does that include humidity, or just temperature?

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By "climate controlled" I mean temperature, but I also run a dehumidifier and pay special attention to outside conditions as well.

What's the best way to thin out the clearcoat?

I've always followed the manufactures instructions ... 4:1 ratio I believe?

If I add more reducer, wouldn't I just be adding more solvent? :D

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By "climate controlled" I mean temperature, but I also run a dehumidifier and pay special attention to outside conditions as well.

What's the best way to thin out the clearcoat?

I've always followed the manufactures instructions ... 4:1 ratio I believe?

If I add more reducer, wouldn't I just be adding more solvent? :D

Yes but it's slower to flach so the solvent has more time to escape.

Also there are different temperature reducers in some systems that slow or accelerate flashing.

Edited by syxxstring
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RAI6 you can only let it sit if your product doesn't have sepecific time windows you HAVE to stick too.

True, but if you cannot deliver the project due to these issues, then what's the difference?

That you now have solvent pop and adhesion issues. The guys that write the tech sheets do a lot of testing and know what they're doing in my experience.

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By "climate controlled" I mean temperature, but I also run a dehumidifier and pay special attention to outside conditions as well.

What's the best way to thin out the clearcoat?

I've always followed the manufactures instructions ... 4:1 ratio I believe?

If I add more reducer, wouldn't I just be adding more solvent? :D

Yes but it's slower to flach so the solvent has more time to escape.

Also there are different temperature reducers in some systems that slow or accelerate flashing.

Yeah, I'm well aware of the temperature rating on reducers ... I use the slowest possible reducer.

So you're saying to increase the amount of reducer and this will slow the curing process and allow it to flow nicer?

How much more do you suggest? 4:2 ratio maybe?

Thanks for the help. :D

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Well instead of spraying it with the mix thinned out more, I think everyone is trying to say spray a thinner layer on the guitar. Instead of going to a full wet coat that is not far from running, try spraying a coat that is medium wet. Just enough to get a layer that will flow out and no more than that.

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Thats right, too much of a good thing is what happened. I've had the same thing happen with laquer, only in my case it was due to heat buildup in the BLACK paint. But basically, you aren't giving the coating enough time to gas off. That means either too much heat and its skinning over and solvent cannot evaporate ie. being trapped in the finish, OR too much being laid down and the surface is drying before all that solvent can escape. Like someone said, thin out your urethane and / or shoot thinner coats.

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I would say this is solvent pop and has nothing to do with contaminants. Basically as said before the surface is drying before the clear below can gas out and it causes small bubbles. This can be a issue of the coat thickness or not letting the previous coat flash long enough before recoating. I live in New Orleans and it is hot and humind and I lay it on thick and very rarely see any pop. I like to use the Dupont Chroma clear 7900 which is a 3/1 mix. You do not use any reducer with this clear so the chance for pop is greatly reduced. It can also be reduced some with blender but then you have to spray much thinner and increase the flash times between coats. On the bicycle frames that I paint I use 2 wet coats and flow it like glass and pop has never been a issue. The great thing with the 7900 is the high build with a few coats.

this is a example of my clear with the 7900, 2 coats and no polishing. this is a professional photo shoot from kgsbikes.com . All of the lettering and color is painted also!

DownTubeLogo.JPG

ForkLogo.JPG

Edited by PaintIt
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I would say this is solvent pop and has nothing to do with contaminants. Basically as said before the surface is drying before the clear below can gas out and it causes small bubbles. This can be a issue of the coat thickness or not letting the previous coat flash long enough before recoating. I live in New Orleans and it is hot and humind and I lay it on thick and very rarely see any pop. I like to use the Dupont Chroma clear 7900 which is a 3/1 mix. You do not use any reducer with this clear so the chance for pop is greatly reduced. It can also be reduced some with blender but then you have to spray much thinner and increase the flash times between coats. On the bicycle frames that I paint I use 2 wet coats and flow it like glass and pop has never been a issue. The great thing with the 7900 is the high build with a few coats.

this is a example of my clear with the 7900, 2 coats and no polishing. this is a professional photo shoot from kgsbikes.com . All of the lettering and color is painted also!

DownTubeLogo.JPG

ForkLogo.JPG

I've used Chroma Clear and yes ... I get solvent pop.

I follow instruction sheets to a T, so there's no chance of not allowing coats to flash long enough.

I don't mean to sound unappreciative, but I've heard all of this before and have already tried everything mentioned here in this thread ... THAT"S what makes this so frustrating.

Just curious ... what psi's are you guys running at the compressor vs. the gun?

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I just switched from an Iwata LPH-80 for my clear gun to a Sata 3000rp.

I run about 80 at the compressor, and reduce it with a regulator in the booth. The Sata I start around 29 psi and adjust from there the Iwata around 20.

Make sure you are using a regulator to control your air presure not an air adjusting valve or a cheater valve on the gun. Regulators keep presure constant, cheater valves or air adjusting valves work by percentage so as available air goes down your air to the gun goes down and you loose atomization.

I doubt this is causing your problems DGW, but want to make sure anyone reading this gets the info. I didn't know any of this until I took some tech training and it blew my mind.

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I just switched from an Iwata LPH-80 for my clear gun to a Sata 3000rp.

I run about 80 at the compressor, and reduce it with a regulator in the booth. The Sata I start around 29 psi and adjust from there the Iwata around 20.

Make sure you are using a regulator to control your air presure not an air adjusting valve or a cheater valve on the gun. Regulators keep presure constant, cheater valves or air adjusting valves work by percentage so as available air goes down your air to the gun goes down and you loose atomization.

I doubt this is causing your problems DGW, but want to make sure anyone reading this gets the info. I didn't know any of this until I took some tech training and it blew my mind.

I'm running 80psi at the compressor and adjust down to 20psi at the gun, so that's good to hear.

I'm glad you mentioned the regulator because one thing I've noticed is that the clear tends to "spit" when I try to shoot light coats.

I've tried all sorts of adjustments at the gun (Devilbiss w/ 1.4 nozzel)) and nothing works ... I either get dry dust (too much air) or it "spits". This is why I asked the question about psi and is also the reason I asked about thinning out the clear by adding more reducer. But now that you mention the regulator, I'm thinking maybe I should try this. I'm pretty sure what I'm using now is just a cheater valve.

Any suggestions as to what type/brand regulator I should be looking at?

Do you think this will help?

Edited by DGW
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Regulators are regulators or so I'm told. The thing to watch also is if your gun has a built in air control that's a cheater valve too. The best way to know is to buy something labeled as a regulator on the package. Before I took the HOK class I bought air adjusting valves thinking they were regulators.

Also check out the How To Spray article in I think this months Rod & Custom. It's by Brian Lynch, HOK's tech guy and the guy who taught my class. It's very good stuff.

Regulator:

8005A.gif

Air Adjusting Valve/Cheater Valve:

WS11.gif

Edited by syxxstring
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I run about the same on my compressor and gun. I also use a Iwata LPH400 for clear but it is overkill on something like a guitar ora bike frame.

DGW - I think that a 1.4 tip may be your issue. You would need to move pretty quick to not build a really thick coat. I use a 1.0 in my Sata Mini Jet and this allow me to slow down which really helps in the tight areas that get overlap. I am guessing that you see the most pop in areas that get overlapped while clearing and the flatter areas that get sprayed thinner are better.

Ther are a few ways to spra thinner coats - Thinner clear or move faster or both . Adjusting the gun to each method is important but I would not usually go down on air pressure to spray a thick clear thinner. once you get the gun spraying correctly leave it and learnhow to spray with it. I have used the same settings on my gun for about 4 years and it always works. I would suggest that you start doing some practive spraying and get as much gun time as possible.

Edited by PaintIt
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