What spray gun settings do you use?

Matty84

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As the title. I’m wondering everybodies preferred settings for nitrocellulose- such as air flow, fan size, paint feed, distance you spray from.
 

Timbresmith1

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It’s all kind of inter-related in my world. Depends on the viscosity of the material at the air temp I’m spraying at.
I start with med fan, no material flow and slowly dial up material flow. Add material or spray closer if material goes on grainy
 

Freeman Keller

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First comment, I am a totally amateur finisher. I would have to look at my gun to tell you exactly what the settings are but basically is 35 psi at the compressor, 20 at the gun. Medium pattern, I open the flow until I get the wetness that I want (which seems to depend on how much I've reduced the lacquer). Inexpensive small gravity feed gun from a local auto paint store, I don't know what the nozzle size is. I shoot lacquer. I finish guitars laying flat on their back or top on a low table that I can walk around - sometimes I shoot across the top, sometimes at the sides, usually about 45 degrees.

I am totally anal about cleaning the gun after every use, I know I don't have to but it takes five minutes and always works the next time.

edit to add, I forgot that I always spray a vertical pattern, but I'm not sure why
 
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Timbresmith1

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It’s all kind of inter-related in my world. Depends on the viscosity of the material at the air temp I’m spraying at.
I start with med fan, no material flow and slowly dial up material flow. Add material or spray closer if material goes on grainy
Hvlp turbine, so not really able to give you a meaningful cfm number.
 

Silverface

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preferred settings for nitrocellulose
There is no such thing as a "preferred setting." You're essentially asking "how do I coat a guitar?" because there about a hundred variables involved!

Settings depend on what equipment you are using (if an HVLP the vary in the CFM and fluid output, and again depending on where in the 4-10PSI fluid range you're running); the viscosity of the material; the size of the needle/air cap (and their age/amount of wear) - plus ambient temperature and several other variables.

And if you are using conventional high-pressure spray...which is ill-advised due to far less control and losing most of your material to overspray - EVERYTHING is different.

You can get guide settings from your equipment supplier by taking a training course - That'll at least tell you how to use the equipment.

But "Guide settings" are only useful if someone is using the exact same equipment, spraying the same brand (and type - sealer, toner, color, clear) of lacquer, using the same Zahn cup thinning ratios for each, at the same ambient temperature and hopefully using some type of jig to have the piece oriented to you spray only vertical surfaces - never across them.

So in the real world - it's a waste of time. Study other threads and watch videos - then practice on scrap until YOU get the entire coating system right; when you're done you should be able to buff it out 2 hours after you spray the last coat (if using conventional lacquers).

If you need to wet sand something is wrong. Wet sanding is only for repairing things like orange peel or uneven mil thickness.

It sounds like you have never done this before...but it's hard to tell because you'd need to explain your equipment, the conditions, and whart material;s you are applying.

And then replies...complete ones... would be several paragraphs ;long each, and STILL tell you to practice on scrap - because you have to figure out YOUR settings for YOUR equipment, conditions and materials
 

Matty84

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There is no such thing as a "preferred setting." You're essentially asking "how do I coat a guitar?" because there about a hundred variables involved!

Settings depend on what equipment you are using (if an HVLP the vary in the CFM and fluid output, and again depending on where in the 4-10PSI fluid range you're running); the viscosity of the material; the size of the needle/air cap (and their age/amount of wear) - plus ambient temperature and several other variables.

And if you are using conventional high-pressure spray...which is ill-advised due to far less control and losing most of your material to overspray - EVERYTHING is different.

You can get guide settings from your equipment supplier by taking a training course - That'll at least tell you how to use the equipment.

But "Guide settings" are only useful if someone is using the exact same equipment, spraying the same brand (and type - sealer, toner, color, clear) of lacquer, using the same Zahn cup thinning ratios for each, at the same ambient temperature and hopefully using some type of jig to have the piece oriented to you spray only vertical surfaces - never across them.

So in the real world - it's a waste of time. Study other threads and watch videos - then practice on scrap until YOU get the entire coating system right; when you're done you should be able to buff it out 2 hours after you spray the last coat (if using conventional lacquers).

If you need to wet sand something is wrong. Wet sanding is only for repairing things like orange peel or uneven mil thickness.

It sounds like you have never done this before...but it's hard to tell because you'd need to explain your equipment, the conditions, and whart material;s you are applying.

And then replies...complete ones... would be several paragraphs ;long each, and STILL tell you to practice on scrap - because you have to figure out YOUR settings for YOUR equipment, conditions and materials
Thanks for the detailed response.

This is my first time using a spray gun for paint. Used many times for glue, but obviously the technique and settings will vastly differ. I’m using a Morrells signature 1 spray gun and I couldn’t tell you the psi as it’s a huge compressor at work that’s used for all the airlines and cnc machinery.

My intention is to test on scrap until I’m completely happy with my setting, however I was interested in hearing people’s own techniques and personal settings.

I was under the impression that all spray jobs needed wet sanding as it seems to be mentioned on every thread I’ve seen!
Also I thought the paint has to cure for 1-4 weeks before any buffing takes place?
 

Freeman Keller

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I was under the impression that all spray jobs needed wet sanding as it seems to be mentioned on every thread I’ve seen!
Also I thought the paint has to cure for 1-4 weeks before any buffing takes place?

If you can lay down perfect coats including the last one you don't need to wet sand. I can't so I do. I also follow the manufacturer's instructions for drying, recoat and buffing time. So far they haven't failed me. I'm not a pro, I don't need to push product out the door so I take my time.
 

Matty84

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If you can lay down perfect coats including the last one you don't need to wet sand. I can't so I do. I also follow the manufacturer's instructions for drying, recoat and buffing time. So far they haven't failed me. I'm not a pro, I don't need to push product out the door so I take my time.
Man, I’m gonna be wet sanding the hell out of this guitar lol
 

Jim_in_PA

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I'll echo the others...there are so many variables that there can never be a "preferred" setting for a gun. That includes different guns, different air delivery systems, different finishes (brand and dilution), etc. What really IS important is to document what works with your gun and air delivery system for a specific product so that when you use it the next time, your setup will be quicker...load it up, dial in what worked before, test shoot and adjust, and then move on to spraying your project.
 

old wrench

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Thanks for the detailed response.

This is my first time using a spray gun for paint. Used many times for glue, but obviously the technique and settings will vastly differ. I’m using a Morrells signature 1 spray gun and I couldn’t tell you the psi as it’s a huge compressor at work that’s used for all the airlines and cnc machinery.

My intention is to test on scrap until I’m completely happy with my setting, however I was interested in hearing people’s own techniques and personal settings.

I was under the impression that all spray jobs needed wet sanding as it seems to be mentioned on every thread I’ve seen!
Also I thought the paint has to cure for 1-4 weeks before any buffing takes place?


It's very helpful to know what your air pressure is at the spray gun - not at the compressor itself.

That's pretty easily done by using a small inline regulator and gauge either right at gun or maybe at the start of a short run of extra-flexible hose (like a whip-line) that runs directly to your gun.

I did a lot of reading and research about spraying, but other than some technical information - stuff like cap and needle sizes for different coatings, most of what I know about spraying finishes comes directly from practical experience and lots of practice - there is no substitute for it.

I have a few different guns, and I use different settings on each of them - so the settings I use on anyone of them would most probably be of very little use to you with your spray gun :)

As goofy as it sounds, spraying water on cardboard will show you a lot about how your gun reacts to different settings like fan size, fluid volume, and pressure, and it costs nothing but a little time.

Once you get familiar with the controls (which are pretty basic), spraying your choice of finish on cardboard will show you how get to get a nice even pass while keeping the gun perpendicular to and at the same distance from your work piece and how much to overlap successive passes - having good lighting so I can clearly see how my passes are laying down is what helps me the most to get an even finish - you really have to be able see what you are doing ;)


Get yourself the right PPE and jump right in there and start practicing - you'll learn :)

.
 

Freeman Keller

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Matty, I'm going to give a big plus one to everything Old Wrench just said. Again, my disclaimer, I'm an amateur, have learned by experimenting and making mistakes. I have found this to be extremely helpful

1642356483004.png


In fact on page 62 Dan goes thru the procedure for adjusting and coordinating the two or three knobs on most spray guns. The other good reference for learning how to spray guitar finishes is on ReRanche's web site.

As OW said, knowing (and adjusting) the pressure at the gun is very helpful. I have a regulator and gauge at the quick disconnect on the gun

IMG_6197.JPG


I make it a point every time I spray to first make a pass on a piece of cardboard and look at the pattern. Sure I'm wasting finish, you'd be surprised how often I make a little adjustment and then another pass.

I also can't over stress cleanliness - I know lots of people leave finish in the gun if they are going to shoot another coat in a half hour, I dump it out, clean the gun, shoot a tiny bit of thinner and never have trouble. I used to get in a hurry and I did have problems.

The other thing I will stress is the conditions in which you are spraying. I don't have a booth, I made something out of cardboard but for the little bit of finishing I do its just as easy to take it outside where I have good light and ventilation. However I have to be careful about temperature and humidity. The one bad lacquer finish that I got I almost knew before I started - the humidity was way to high and I was pushing it. I have a guitar on my bench right now that is ready for finish but its going to wait until March and the conditions are right.

Reread Old Wrench's post a couple of times. If you follow his advise you will get good consistent results and you will learn about your gun, your products and your guitars. Good luck
 

Matty84

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Thanks for all the input. I’ve sprayed the colour on now. Had some trial and error with scrap before hand but the final job went on surprisingly easily. Waiting to see how it looks once dried.
 




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