Airless vs Conversion or HVLP
#11
I don't have much experience with either. Been doing some reading about them and it is stated that one of the disadvantages of airless sprayers is a lot of over spray. Isn't over spray defined as the amount of product that gets past the work piece? So, if you are spraying a small item, you are likely to have a lot of product go past it. If you are spraying a wall - very little. If that is a correct definition, why would one type of sprayer have more over spray (as a general statement) than another?

I would assume (no experience) that an airless sprayer would create less "fog" and, therefore, be better suited to working is a small space? ?
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#12
If you already own a large air compressor get an HVLP conversion gun.  Cheapest option, and best option for spraying furniture and cabinets depending upon how much you spend.  Even the $10 purple HF gun sprays shellac and low viscosity finishes remarkably well.  If you don't own a compressor, but want one, that's still the best option.  If you don't own a compressor and don't want one then a turbine HVLP unit is the best option for furniture and cabinets. 

I don't know enough about airless units to have any useful input. 

John
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#13
(08-20-2017, 08:40 PM)jteneyck Wrote: If you already own a large air compressor get an HVLP conversion gun.  Cheapest option, and best option for spraying furniture and cabinets depending upon how much you spend.  Even the $10 purple HF gun sprays shellac and low viscosity finishes remarkably well.  If you don't own a compressor, but want one, that's still the best option.  If you don't own a compressor and don't want one then a turbine HVLP unit is the best option for furniture and cabinets. 

I don't know enough about airless units to have any useful input. 

John

I agree with everything he said.

Airless equipment is typically used for shooting large quantities of thick paint like interior/exterior latex. The really aren't much use for anything else.

Small tight spaces are a pain with any spray gun because the air (and paint) blows right back at the gun when spraying. Sometimes a brush is the right equipment.

1. HVLP/Turbine guns powered by small turbine fans use high air volume to move and atomize the paint. Lots of low pressure air. About 6-8psi. 8psi won't carry overspray very far and it won't pull a lot of paint out of the gun... less over-spray

2. Conversion guns are traditional spray guns with a regulator (powered by a compressor) at the air inlet which chokes off air volume and adjusts inlet pressure to the gun. It still used high pressure to atomize the finish and it does a better job of atomizing than a turbine gun and it carries more finish further and makes more of a "cloud" because of the more efficient atomization... so... more over-spray.

3. Airless units pressurize the paint with a pump and basically squirt it out the spray nozzle but because of the high pressure, it atomizes to some extent. They are really better for heavy/thick (high viscosity) finishes like latex and other single stage industrial finishes like urethane paint. They aren't suited well for laying out a nice glass-like finish for furniture, automotive etc type topcoats.

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1 will probably suit your needs, has a longer learning curve than 2 or 3 but won't do as well with more viscous finishes as 2 or 3. This equipment can be pricey because you need a turbine and a decent one with a gun will start at about $700. I use these quite often and my guns run about $300 a piece. There are some inexpensive plastic ones available but they don't come anywhere near 8psi and don't put out as much air of finish. They are even more limited in their abilities.

2 will give you the best finish with a wide variety of finishes and has more flexibility and is probably the cheapest option, assuming you have a sufficient compressor.

3 If I were a contractor, I'd own one. Very limited for the woodworker and hobbyist. Expensive. Not well suited for small work. Very well suited for wals, ceilings etc.

Note: To help prevent "blow back" in small confined areas, try to hold the gun at an angle to the surface so the air glances off the work and doesn't hit "head on" and bounce straight back at the gun. You can also tighten up the spray pattern and dial down the air and finish volumes. I d this when I'm doind work in confined spaces like door jambs.

Practice.
Neil Summers Home Inspections




" What would Fred do?"

... CLETUS











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#14
Thanks for all the terrific comments and suggestions. Very helpful information. However, it doesn't actually answer the basic question; what is over spray and which system type produces the most and why?
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#15
(08-21-2017, 09:54 AM)Willyou Wrote: Thanks for all the terrific comments and suggestions. Very helpful information. However, it doesn't actually answer the basic question; what is over spray and which system type produces the most and why?

S.H.'s answer does cover the topic of how much and why.

Overspray is simply material that doesn't get onto the project.  Trying to give it a single number that is correct for all situations just isn't possible.  It is going to be a function of gun type, gun & air source settings, material being sprayed, target being sprayed, technique, etc.

Reading a number like 12% vs 13% for one system versus another has no meaning.  Lower pressure and better atomization (smaller particles) means let overspray/bounceback.
Don't sweat the petty things and don't pet the sweaty things. -- G. Carlin
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#16
What you are saying makes sense. However, I'm just trying to understand several on-line reviews I've read that state that airless sprayers have a down side of creating more over spray than the others (HVLP & conversion) under similar test conditions. There are no reasons provided. I would not have guessed that would be so. Discounting any discussion of finish quality, it seems to me that spraying pure product without inclusion of air should result in less blow-back and/or fogging. Is this not true?
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#17
(08-21-2017, 04:08 PM)Willyou Wrote: What you are saying makes sense. However, I'm just trying to understand several on-line reviews I've read that state that airless sprayers have a down side of creating more over spray than the others (HVLP & conversion) under similar test conditions. There are no reasons provided. I would not have guessed that would be so. Discounting any discussion of finish quality, it seems to me that spraying pure product without inclusion of air should result in less blow-back and/or fogging. Is this not true?

Not to pick nits but I don't see why these three products would be tested under similar situations. It's like testing an F-150 against a Corolla and a Civic. An airless sprayer would rarely if ever be used for the same things as a Turbine gun or a Conversion gun. It would be rare if someone was shooting the same finishes with a turbine or conversion gun as what is normally shot through an airless sprayer (latex).

The least amount of over-spray would be from the Turbine Gun (some are better than others), followed by the conversion gun, followed by a traditional gun (or a conversion gun with the regulator removed) , followed by the Airless sprayer. An airless sprayer is probably pushing out 10X the finish in the same amount of time as a turbine or conversion gun.

Typically finishes are measured by the ounce or gram, maybe a pint and in some cases a quart for Turbine and Conversion guns. Finishes are measured in gallons with airless equipment. Airless is not intended to be used for the same projects or finishes as turbine or conversion guns.
Neil Summers Home Inspections




" What would Fred do?"

... CLETUS











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#18
Thanks for the good summary. You know how it is when "they" review stuff. They try to create a level playing field for even comparison. It doesn't always work as planned.
I think the airless comparison they were talking about was the smaller hand held units that use quart or pint containers, not the big ones that suck from gallon or 5 gallon buckets. My house painter a few years ago had one of those for spraying house stain and it was impressive, but certainly not suitable for furniture or cabinet work.
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#19
ok, I guess you are talking about the electric Wagner type sprayers. That would make sense. They are really not intended to lay out a nice finish. They're purpose is to get finish from the gun to whatever is being sprayed. Like deck stain or house paint. If I were painting a deck or house, I would consider one but not for much else.
Neil Summers Home Inspections




" What would Fred do?"

... CLETUS











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#20
Thanks for your help.
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