Spray Gun purchase advice

[will delaney]

I am interested in buying a spray gun for paint and stains. I do have a Porter Cable compressor 8 hp 6 gal tank which I can use.   It will be using for furniture projects.  Any advice or suggestions? Thanks Will

[John Schaben]

Not sure which compressor you have, 8 HP with a 6 gal tank doesn't sound right. Hp and tank size are relatively immaterial compared to the CFM@PSI specification.

[will delaney]

It the Porter Cable nailer combo compressor with 150 psi 2.6scfm@ 90 psi. So what do you think John?

[John Schaben]

Hi Will - That sounds like the same compressor I have, specs are the same anyway. I'm afraid you will have a difficult time finding a gun that the compressor will be able to keep happy. From a budget standpoint, I would recommend you investigate some of the HVLP systems. They are a self contained air supply of 100+ CFM at 4 to 6 PSI and do an excellent job. About like painting with an aerosol can. Reasonably good quality systems can be had starting around $100, not a lot more than a quality compressor powered spray gun.

[Don Homer]

Get an Earles  HVLP unit .  Great finishes and reasonably priced. Sprays everything and you get professional results !!!

[will delaney]

Just took a look at the Earlex and it appears they have a great HVLP system. It appears like this system has a small learning curve for a person with little experience in spray finishing.

[John Schaben]

I've got the Earlex 3500. You're right, there is a very small learning curve with it. My only complaints about it are that the hose is pretty short (9 ft) so you end up carrying the blower assembly around if your project is of any size. Not a real biggie as it only weighs 5 or 6 lbs. The other complaint I have is the air intake is on the bottom of the unit so it will pick up dust particles from directly beneath it. The filter is a coarse, open cell foam so it only filters out brick and small animals.

will delaney said:

Just took a look at the Earlex and it appears they have a great HVLP system. It appears like this system has a small learning curve for a person with little experience in spray finishing.

[Alex Shiells]

Hi Will, 

 

I have been doing some research on this recently and this is what I found:

There are two main types of guns that you can get namely a LVLP (low volume, low pressure) and a HVLP (High Volume, Low pressure).

 

The typical figures are as follow:

LVLP: 29-43 PSI; 3-3.9 CFM

HVLP: 14-43 PSI; 4.2-7.1 CFM

 

CFM (cubic feet per minute) is the main aspect that you are dealing with. The pressure (PSI) is pretty much low enough for all compressors to handle. The CFM is how fast the tank is going to consumed. Now you will see that if your compressor can not maintain a flow of 7.1 cfm you are going to have your compressor cycle and try compress to pressure again. Now compressors also have a duty cycle. E.G. 60% duty means that out of a 10 minute cycle it will have to "rest" for 4 minutes. Now this can be a problem if you are busy with a job and you run out of air half way through a panel. You will be able to spray with a smaller tank but you are going to have to stop start a lot.

 

So in summary you want to have a look at the gun you are using and check out the CFM and at least double it if you want to spray constantly. The bigger the tank the longer the store which helps with the duty cycle. V-Belt driven compressors are quieter and last longer they say. 

 

Hope that helps.

[John Schaben]

Good, informative post Alex - Thanks

Alex Shiells said:

Hi Will, 

 

I have been doing some research on this recently and this is what I found:

There are two main types of guns that you can get namely a LVLP (low volume, low pressure) and a HVLP (High Volume, Low pressure).

 

The typical figures are as follow:

LVLP: 29-43 PSI; 3-3.9 CFM

HVLP: 14-43 PSI; 4.2-7.1 CFM

 

CFM (cubic feet per minute) is the main aspect that you are dealing with. The pressure (PSI) is pretty much low enough for all compressors to handle. The CFM is how fast the tank is going to consumed. Now you will see that if your compressor can not maintain a flow of 7.1 cfm you are going to have your compressor cycle and try compress to pressure again. Now compressors also have a duty cycle. E.G. 60% duty means that out of a 10 minute cycle it will have to "rest" for 4 minutes. Now this can be a problem if you are busy with a job and you run out of air half way through a panel. You will be able to spray with a smaller tank but you are going to have to stop start a lot.

 

So in summary you want to have a look at the gun you are using and check out the CFM and at least double it if you want to spray constantly. The bigger the tank the longer the store which helps with the duty cycle. V-Belt driven compressors are quieter and last longer they say. 

 

Hope that helps.

[will delaney]

Thanks for all the information. This advice is going to save me a lot of time frustration and money. My compressor is not  really suitable for a spray gun so I have decided to buy hvlp turbine system. The Earlex has a pretty reasonable price with lots of good reviews. I'm considering the 5500 model. It appears to have my profile to buying your last one first.   When placing an order I would like to get the extra spray needles. The unit comes with a #2. Which ones would help me have an all around system?  Thanks again for all the input.

[Alex Shiells]

Hey Will, 

 

Okay I have had a look at the Earlex 5500 and it looks fine. The needles are all dependent on what material you are spraying. Basically if you think about it, the thinker the material and the smaller the needle the more pressure you will need to get it to atomize out of the gun. Now if you are not atomizing (making the material into a fine mist) well you will start to get a orange peel effect on your finish. You really really don't want that. You can fix anything besides paint runs and orange peel effect when the material dries on too thick.

 

The smaller the needle to more viscose the material. I would suggest that you get a 1.5mm needle. It is a bit of a all rounder needle. I only use that. What I would really suggest is a viscosity cup. It takes all the guess work out of everything. You will see at the bottom of this link http://www.earlex.com/hv5500-accessories.php they have all the run times. So what you do is thin the material according to the manufactures specs. Be sure to use the thinning material that is recommended ONLY. Otherwise you get all sorts of issues like waxy build ups, runs, material that will not dry and and and. If you have thinned your material down to the manufactures specs and the viscosity drip test checks out you will be good to go.

 

You know how to spray? Pattern settings, air flow, movement across the surface and over spray etc?

 

[DAVID CZUPRYN]

If you do buy this, let us know how it performs. I've done lots of research on this topic, attended live demostrations, talked to factory reps and burned up the net. Alex offers good advice,especially concerning the viscosity cup drip test. If,after thinning to man. specs. you pass the drip test,you're good to go. What if you don't pass? What then? Reduce more? All reps told me, if you're going to spray "heavy latex", you need a five stage turbine!! Stains, inks and dyes are fine using smaller turbines. How long is the hose? Sound like a silly question? It's not. Manufactures determine hose length,according to the strength and power of the turbine. Turbines generate lots of heat. Where does it go? Into the hose? What happens to the reducer in the coating being sprayed,when it's exposed to temperatures of 80-90 degrees F. ?? Can this lead to problems? According to web site discussions, it IS a problem. A good turbine system, should exhaust the heat and NOT through the hose. I've downloaded manufactures manuals and most of them suggest using a slow thinner,and a paint additive {to slow the drying time} to attempt to compensate for this heated air. Where does the hose attatch to the gun? At the bottom of the handle, or the back of the gun? In this case, the back of the gun. Why? It's trying to get the all the power the turbine can generate to atomise and break up the coating. This set-up, may change the gun to a bleeder type. This configuration is usually used to spray very heavilly viscosity coatings,such as multispec. I'm open to any comments, that anyone else would care to share with the rest of the community. Hope this helps. Dave

[John Schaben]

Thanks for another VERY informative post.

I really hadn't thought about the exhaust heat of the turbines before. Just one point though. Multi stage systems tend to be pretty pricey, far out of my budget at the moment. I have found with latex paints though is, while not ignoring the mfg instructions on the can completely,  exceeding the recommended thinning until I could get an acceptable spray worked pretty well. It did take several more coats, but they could be applied almost immediately. I usually thin with Floetrol, not to exceed 10% and if more thinning is needed, bottled water. More than 10% Floetrol will affect the sheen.

Now, what excessive thinning will do with oil based products, I have no idea.

DAVID CZUPRYN said:

If you do buy this, let us know how it performs. I've done lots of research on this topic, attended live demostrations, talked to factory reps and burned up the net. Alex offers good advice,especially concerning the viscosity cup drip test. If,after thinning to man. specs. you pass the drip test,you're good to go. What if you don't pass? What then? Reduce more? All reps told me, if you're going to spray "heavy latex", you need a five stage turbine!! Stains, inks and dyes are fine using smaller turbines. How long is the hose? Sound like a silly question? It's not. Manufactures determine hose length,according to the strength and power of the turbine. Turbines generate lots of heat. Where does it go? Into the hose? What happens to the reducer in the coating being sprayed,when it's exposed to temperatures of 80-90 degrees F. ?? Can this lead to problems? According to web site discussions, it IS a problem. A good turbine system, should exhaust the heat and NOT through the hose. I've downloaded manufactures manuals and most of them suggest using a slow thinner,and a paint additive {to slow the drying time} to attempt to compensate for this heated air. Where does the hose attatch to the gun? At the bottom of the handle, or the back of the gun? In this case, the back of the gun. Why? It's trying to get the all the power the turbine can generate to atomise and break up the coating. This set-up, may change the gun to a bleeder type. This configuration is usually used to spray very heavilly viscosity coatings,such as multispec. I'm open to any comments, that anyone else would care to share with the rest of the community. Hope this helps. Dave