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So how do you spray with Nitro in order to avoid orange peel? I've got a gun and compressor and have tried lighter volume, higher volume, less air pressure, more air pressure, etc... but still get the orange peel. I hold the gun about 10 inches away when spraying and move side to side parallel with the guitar surface. My gun is rated to use no more than 40 psi. Currently I have the compressor out set to 40psi. Am I suppose to be able to attain a level surface during each spray, or should I just focus on getting a level surface during final sanding before buffing???

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Barron Wesley Guitars

If you mean the finish orange peels when dry,it does that. You have to sand it smooth with 600 wet or dry,and mildly soapy water. At least,that's what I use. Then rub or buff for the final polish.

What kind of gun?

A Husky Gun. I'll get the model soon..

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Barron Wesley Guitars

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Do you have a filter in the airline to drop out moisture??

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"Everyone wants to BE something, but nobody wants to BECOME something" - William Cumpiano

as has already been mentioned, there are a lot of variables to the equation...one thing that hasn't been specified is the compressor's capabilities and the size of its storage tank(s)...it is accepted that the larger the capacity, the more 'oomph' is behind the air which results in a better spray job (as a rule of thumb)...also a BIG factor is the size and length of the air hose...hoses cause friction and there is a big difference between a 1/4" hose and a 3/8" hose in that regards, length of course is an obvious consideration..the point being use as short of a hose as possible, and I for one use a 3/8" hose even though it is heavier as I know it offers far better air flow...

orange peel can also be caused by too high of a pressure...think of the concept of blowing on a pool of water...it creates ripples...

as Todd mentioned, setting the air at the gun is the best....I bet your 40psi at the compressor is translating to 30psi at the most at your gun...I've found that manufacturer's spec sheets are at best a starting point which each user has to refine for their specific situation..

and of course orange peel can also be the result of using an inferior spray gun...you do get what you pay for in general...if the product is not being fully atomized then orange peel is the result..

Thanks guys. All of your comments are helpful.
To answer a few questions:
-I have a relatively cheap Husky HVLP PRO HDS890 L1008 (picked it up at Home Depot)
-My compressor is a Rigid 4.5 gallon tank, 1.8 horse power, with 4.9scfm @ 90psi
-I've kept the air flow at the gun maxed out since I started spraying and is the only thing I haven't changed thus far.
-My hose is 3/8" and I believe 30' in length

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Barron Wesley Guitars

it would be helpfull to have an air control valve and pressure gauge at the gun so that you know what your air pressure is at the gun and to beable to keep an eye on spikes and drops in airpressure and adjust accordingly.

that compressor, IMO, is not up to what is required to properly supply air to an HVLP gun. also that is a lot of hose to be using with such a marginal compressor, as noted make it as short as is possible for your situation.

one thing to note is that its not the static pressure that matters, rather the pass through pressure (i.e. when the trigger is fully pulled) that is what you need to pay attention to. as MDP notes, the use of a regulator/pressure gauge at the gun will allow observation and tweaking of the pressure. With an HVLP gun you are going to be very hard pressed to cause the effect I referred to in my previous past (i.e. too much pressure creating orange peel effects) and I might go further and say with your setup it would be impossible for that to happen, which leads to the most likely conclusion that you don't have enough air supply to properly atomize the lacquer. you can try and thin the material out a bit more, but you will be playing the game of not getting runs if you are putting on a properly wet coat.

in the big picture you can also consider that you are spraying a product you plan on wet sanding and polishing, so even though it will require more effort, you should still be able to get a good finished product.

Mike is correct here it is the pressure while the gun is in operation that is critical. Suppy to the gun in the close position tells very little. I guess I missed the fact you were using a conversion HVLP gun I too feel you are likely under sized on your CFM.

I suppose we need to define orange peel. What I was saying is that you can't expect a sprayed surface to stay mirror smooth. There is always some unevenness after it dries. If there is severe unevenness that is different.

Well thanks for all the input guys. This has given me much to think about. Also after recently talking with someone who has been doing great spray work for many years, he too said I don't have enough cfm to properly spray the nitro with a full size gun. He also suggested if I can't afford to upgrade my air compressor that I should look for a detail or mini gun with a 3.5 or 4 cfm rating to go with my compressor. I guess it still won't be perfect, but may save me some sanding in the long run until I can get more professional level equipment. I hope to transition eventually into making guitars full time.

P.S. I'm now switching to KTM-9 since I don't have the proper enclosure for the hazzerdous part of it. Plus, my neighbors are on 3 sides of my property, and one of them is a daycare.

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Barron Wesley Guitars

Your compressor should be fine for spraying one guitar at a time. If you were painting cars, or multiple guitars you'd need more air, but it's not like you're going to be spraying for more than a couple minutes at a time. Take your time spraying and let the compressor catch up. The only problem with that, is when a compressor constantly runs it builds alot of heat, and the heat cause moisture to build up inside the tank. A good filter is a must. If you're getting minor orange peel that's normal, but if you're getting a pebbley surface it's probably the gun, or setting with the gun. Sometimes new guns have some flashings blocking some of the small holes in, or just behind the air cap. This will keep them from atomizing the finish correctly. I'd make sure all these holes are open. Properly adjusted the finish should come out of the gun as a fog, instead of big droplets. Think of how a rattle can sprays. If you're going to use waterbased finish, make sure your gun is disigned for waterbased finishes.

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I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/

Just looking at what you are using, its possible that the gun and air pressure arent set up at the optimal settings.

that said, I doubt the compressor can really deliver the stated numbers - I have a 20 gal 5hp (OK, I know that 5hp is impossible with 120V) that is supposed to deliver 5.7 @90psi, and use a Sata minijet 4 using about 20 PSI at the gun, and my compressor comes on every once and a while.

I also had tried a cheaper CH conversion HVLP, and no matter where I had it set I got lots of peel, more than my cheaper CH touch up high pressure gun - it plain and simple isnt cut out for a guitar finish.

Your compressor is likely OK to use going forward, but I would honestly spend the money at the other end first, get a really good gun. I looked at a bunch, and the tag line always seemed to be "as good as a Sata". So I just got the Sata. I figured no use getting something to find out its not up to the task.

Its like having a great stereo and crappy speakers, or playing an Olson with 2 year old strings, and wondering why your 87 Yammy ply top at home sounds better.

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

Okay - so I'm learning a lot here. So this is my next question considering the comments that my compressor should have enough oomf.
My compressor puts out 4.9scfm @90psi, but my gun air Requirements are 6.5 scfm @ 40psi. So I'm thinking and have been advised that my gun is starving for the proper amount of air..

On another note, I have been able to lay it on thicker to reduce the orange peel, but I would like to do many thin coats over time instead of globs from the beginning.

I know that in the end, sanding is needed and people have worked with less. I'm trying to minimize time spent where I can since I work a full time job as well like most of you I'm sure.

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Barron Wesley Guitars

What everyone is saying is that when your gun is starved, to properly atomize so that you don't get orange peel may require more media fluid per coat. Therefore a heaver coat. you can try to thin your fluid (finish) by about 10 % with a proper reducer and it may help it flow out level before it gels. but the real key to be consistent is having more than min required cfm at all times Also it would help to understand that most manufactures of compressors list peak CFM at a given psi. So you may not be getting 4.2 or what ever cfm at 90 psi except when the tank is fully pressurized. When the pump is cycling you may only be getting 3.5 cfm That is why it is best to have a compressor rated at 10% over the max consumption you need.

The gun isn't starved for air until the compressor (pump) can no longer keep up. CFM ratings are what the pump can pump, not how much air can actually flow out of the tank. As long as the PSI inside the tank remains above the regulator setting nothing is starved. If you're spraying at 40 psi, as long as the pressure in the tank remains above that it doesn't matter if the pump is 1000 CFM or 1 CFM. The smaller pump will eventually.......get behind, and pressure in the tank will drop. This is when the gun is starved for air, not before. A bigger tank has more reserve, and a bigger "pump" (usually more horsepower) has more capacity. Spraying something small like a single guitar doesn't put a very big demand on the reserve so CFM ratings can be lower.

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I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/