Can a 3 turbine HVLP gun spray clear without OP?

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Can a 3 turbine HVLP gun spray clear without OP?

Postby Jim Dewar » Thu May 24, 2018 12:34 pm

Hi All
This is my first post so I will make it about my number one guitar making nemesis - orange peel.
I have the Fuji Mini-Mite 3 with the T75G gravity feed gun with the stock 1.3 cap. So far I have tried Single Stage and for the last year Cromax 2K paints. My spray booth is usually in the 60’s to 70 degrees. I now use a slow reducer and my activator is for 80 to 90 degrees. I have experimented with thinning my clear and I also spray a lot closer now, about 3 to 4 inches away from the guitar. I have tried all settings of fluid control. No matter what I do I get OP. What I have come to learn is that the OP in the layers after the first layer don’t matter as the need to be sanded away to get to the first layer. All my layers have OP. If the first layer has OP, which mine do, then there’s no “sanding it out” since that just brings you to sand-through. So I guess my question for you all is...
Has anybody ever sprayed 2K clear, or any quality clear for a guitar, using a 3 stage tubine HVLP and NOT get any OP?
I’m considering trying pre-cat laquer next but I don’t know much about it.
Anyways, all replies are greatly appreciated.
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Re: Can a 3 turbine HVLP gun spray clear without OP?

Postby David King » Thu May 24, 2018 1:39 pm

Welcome to the MIMF! You might try a cheap Harbor Freight HVLP jam gun for comparison if you have a conventional air compressor available. Are you warming the wood before you spray? That might help flow out or hinder it. You might try a top of the line 2K or 3K like DuPont's Chroma Premier but it's stupid expensive.
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Re: Can a 3 turbine HVLP gun spray clear without OP?

Postby Jim Dewar » Thu May 24, 2018 1:49 pm

Hi David
I thought the Cromax was stupid expensive already.
I leave the bodies in the paint booth for an hour to acclimate to the ambient temp before I paint.
65 to 70 is the usual temp in there.
I don’t have any compressed air.
Have you sprayed clear OP free?
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Re: Can a 3 turbine HVLP gun spray clear without OP?

Postby David King » Sat May 26, 2018 11:54 pm

Jim I haven't sprayed in years and never with a 3 stage HVLP only with a Fuji 4 stage once and that was warmed up lacquer. All the other spraying was done with either conventional HP siphon guns or the HVLP jam gun which was a crude approximation of the SATA minijet. I've sprayed DuPont chromaclear and PPG DCU 2002 which are both low to medium solids 2k clears but the best result by far was that Chroma-premier at around $450/gal. If I could keep the dust down I'd get a nearly perfect flow out over 220grit sanded West systems grain fill. It's around 52% solids IIRC. The gloss is spectacular and buffing out was a breeze compared to polyesters but not as scratch resistant.
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Re: Can a 3 turbine HVLP gun spray clear without OP?

Postby Christ Kacoyannakis » Sun May 27, 2018 9:53 am

I have sprayed with a HVLP turbine gun and gotten a decent finish. My problem is that I just don't have room for a dedicated spray booth, and it takes a lot of time to tarp off an area in my garage, and then it is not heated or cooled or protected from dust. I sort of have decided to switch to French polish on acoustic instruments and brushing finish on electrics. I had to do a lot of sanding after the spray gun anyway, and if I am careful with the brush, it ends up being about the same amount of sanding, but much less setup, cleanup and tear-down. I am only using water based, so I can brush that in my shop.
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Re: Can a 3 turbine HVLP gun spray clear without OP?

Postby Barry Daniels » Sun May 27, 2018 12:02 pm

Orange peel is too much liquid and too much air. Try spraying further from the work piece. I usually stand off about 8" and move fairly quickly. Turn the liquid setting lower.
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Re: Can a 3 turbine HVLP gun spray clear without OP?

Postby Jim Dewar » Tue May 29, 2018 9:41 am

Hi Barry
Thanks for your reply.
With all due respect, everything I have read about OP is the opposite of what you just said regarding the liquid. What I have read is that it can be from either too thick a liquid or to far from the work piece. Supplemental to that would be spraying too fast. In other words, anything that causes the paint to dry too fast or not flow out enough will cause OP.
I just want to know for sure whether or not 2K clear can be sprayed OP free with a 3 stage HVLP turbine system.
So when you say too much liquid, are you referring in anyway to its viscosity or are you saying that the sprayed layer is too thick? If it’s the latter then I would think OP wouldn’t be so much an issue but solvent bubble pops would be.
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Re: Can a 3 turbine HVLP gun spray clear without OP?

Postby Barry Daniels » Wed May 30, 2018 1:20 am

Jim, I looked it up and you may be right about what causes OP. I was only speaking from my limited experience and it always seemed to occur when I got too close or too slow, combined with too high of pressure on the air. Usually adjusting only one of those was sufficient to relieve the OP.
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Re: Can a 3 turbine HVLP gun spray clear without OP?

Postby Jim Dewar » Wed May 30, 2018 9:00 am

Hi Barry
The thing is is that you bring up an interesting idea which I have never seen discussed. Can a layer of clear go on too thick and thus create OP rather than run?
My OP issue is my one single issue preventing me from selling my guitars. I have a pretty cool and innovative guitar but I cannot get that perfect clear. I feel that nobody is going to shell out premium boutique guitar cash for a paint job with OP in it. I went to GC this past weekend and guitars there for $199 had perfect paint jobs.
It’s so damn frustrating.
BTW, how can any guitar be sold for $199? Do the luthiers get paid ten cents an hour for them?
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Re: Can a 3 turbine HVLP gun spray clear without OP?

Postby Paul Rhoney » Wed May 30, 2018 11:48 am

In my experience just about any finish sprayed through just about any gun turbine or otherwise can lay down nicely with little to no orange peel. There are exceptions of course, but primarily what it comes down to is getting to know your spray setup and the product you're using. However even then, you still have the weather to contend with. For that reason I've embraced more of a "it ain't done 'til it's got a run" philosophy to my finishing. Which is to say, if you can't fight clear coat orange peel, then don't try. Just make sure that you get enough clear coat on there that you can knock it down with your cut and buff process. Even my best clear coats still needed a 1500 grit wet sand, so if I'm doing that to the whole guitar anyway, I'd rather focus on making sure my post-finish leveling is on point.
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Re: Can a 3 turbine HVLP gun spray clear without OP?

Postby Brian Evans » Wed May 30, 2018 12:41 pm

Are you spraying colour with base coat/clear coat? What product?
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Re: Can a 3 turbine HVLP gun spray clear without OP?

Postby Jim Dewar » Wed May 30, 2018 1:18 pm

Hi Paul and Brian
Thanks for your replies.
If you read my initial post here you’ll see that the sanding does me no good as my OP starts at the first layer, and you’ll see that I am using Cromax 2k BC/CC.
I’d love to hear from somebody, anybody, that has been able to get a professional clear finish sprayed, sanded and buffed using a 2K clear with a 3 stage turbine HVLP gun.
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Re: Can a 3 turbine HVLP gun spray clear without OP?

Postby David King » Wed May 30, 2018 11:42 pm

Jim,

I'd call the paint company and ask to speak to their techs who will know as much as anyone can about the product. I'd also contact the dealer or the country rep for Fuji to see if they can help you problem solve. It may be as simple as trying a different nozzle size/air cap or the internals of your gun may have gotten fouled up with cured finish and need a rebuild.
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Re: Can a 3 turbine HVLP gun spray clear without OP?

Postby Brian Evans » Thu May 31, 2018 3:19 pm

There must be around a dozen Cromax base coat clear coat systems, but they all probably react about the same. It's an automotive paint system, so if I go back to my car painting days I would look for a slower activator/reducer, reduce the temperature I was spraying in if it was towards the hot side, I would make the first coat a quite light mist coat (almost no coverage, certainly not a wet coat) and as soon as it flashed (2 - 3 minutes maybe) I would do one wet coat. That's all, no other coats, automotive paints are usually not designed for multiple coats like lacquers are. Goes without saying the base coat has to be completely flat. But I never used Cromax, I used mostly DuPont brand. Edit: I googled Dupont, and lookie that - Dupont's new name is Cromax, same company.
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Re: Can a 3 turbine HVLP gun spray clear without OP?

Postby Jim Dewar » Thu May 31, 2018 7:41 pm

Something interesting to note.
I never get OP on the sides. Only the back and front.
I wonder why?
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Re: Can a 3 turbine HVLP gun spray clear without OP?

Postby Barry Daniels » Thu May 31, 2018 10:57 pm

I think it's pretty normal to apply more finish to the top and back than the sides. I have to slow down or add extra coats on the sides to get the same amount of finish as the plates.
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Re: Can a 3 turbine HVLP gun spray clear without OP?

Postby David King » Sun Jun 03, 2018 5:54 pm

DuPont/Cromax will have excellent tech support over the phone, they can certainly afford it. They may try to steer you towards a product designed for custom aircraft interior wood paneling when you tell them you're doing guitars.
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