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Painting with HVLP or Airless Gun?

Streamline's picture

I have extensive crown moulding, 37 doors, and trim work to paint in a 6,000 sf home.  I was going to purchase an HVLP to do the job.  A painter told me that is not a good idea as it will take forever.  He suggests I use an airless gun with a 3 18 spray tip with no filter to get the job done.  I would be using Sherwin Williams ProClassic paint.  Does this sound right?  thx.

(post #81125, reply #1 of 58)

He's right. Use an airless for paint. HVLP is more for clear finishes such a lacquer, varnishes etc. where the viscosity is higher and it atomizes smaller. I don't think I've ever seen HVLP used for paint.

(post #81125, reply #2 of 58)

He's wrong (IMHO). You can absolutely spray paint with HVLP, providing it's a powerful enough unit. I've done it manyyyy times.  The HVLP will give you much less overspray.  If you're planning to buy however, a suitable unit is going to be 700+ simoleans for an entirely self contained unit.


HTH


PaulB


 

(post #81125, reply #9 of 58)

PaulBinCT.


 Not so fast there bucko  ;-)   I have both airless and HVLP and when I paint solid paint the airless makes less overspray mess than the HVLP does on the other hand when I do shellac I'd never go with airless rather the HVLP and pressure pot become my tool..

(post #81125, reply #10 of 58)

Hmmmmmmmmmmm well... I guess we'll just have to call this a rare disagreement ;)


I have both as well and he only time I use my airless is when I have a bigggg job where transfer efficiency and mess aren't a factor.  That is to say... not in a while now ;) But of course... YMMV.


PaulB


 

(post #81125, reply #11 of 58)

Paul,


  OK I failed to mention the covering large areas aspect of an airless sprayer.     However I can easily control the mess aspect with the airless sprayer..  I simply narrow the fan down to a small area and the overspray is a minimum..   It's one of the few tools I don't bother to suit up to use.   While I may a have a few drops on me at the end of spraying the whole house, It's no where near the potential mess I can create with other methods pf paint application..  (sometimes I think it would be faster if I simply jumped into the paint bucket and threw myself on the walls  <grin> 


 Actually I think the original poster was speaking of crown molding because if he was speaking of base molding or walls  and wanted it clear I would tell him to brush it..


  While you cover more area with a sprayer, the taping time and mess clean up is much longer with spraying than brushing..  more than offsetting any speed gains by the equipment..


 

(post #81125, reply #15 of 58)

I have both airless and HVLP and when I paint solid paint the airless makes less overspray mess than the HVLP does


Then you need a lesson on how to set the machine! Dont know if you're aware of it but the HVLP is known for little to no overspray.


You're the only guy that I know that will/could make that claim.


Doug

(post #81125, reply #20 of 58)

Doug U


   Years ago when HVLP first came into use I believed the claims made, purchased my first gun and sprayed without my normal booth.  I still have tools and  tool boxes with over spray on them as a result of that disaster.  I was able to remove the overspray from my cars only because I spent hours buffing away the over spray.


  Thinking that I'd made a major goof somehow I called up the Devilbus rep and asked him over. I reenacted exactly what I'd done previous  and explained that I hadn't used my normal "spray booth " approach because of the claims of HVLP.  He first confirmed that my technique was correct and then informed me that if HVLP was as good as it's claims the sales of paint booths would be declining instead of increasing..


  There will be significantly less over spray than previous guns had but in no way does it eliminate overspray completely.   Due to the lower pressure involved less material will bounce off the object and become that dense cloud I was so used to working in but there is still significant overspray..


  That is unlike my experience with my airless sprayer which I can paint walls with and need only roll out a narrow strip of ground cover to catch any over spray..


 Now granted we are speaking about painting two wildly different materials here.. Clear materials such as shellac or lacquer that are highly thinned and the far more solid and dense latex paints that are unthinned for all intents and purposes.. (sometimes floewtrol is added under certain circumstances) 

(post #81125, reply #26 of 58)

Frenchy is your HVLP gun a compressor or turbine model?

Wallyo

(post #81125, reply #28 of 58)

Wallyo


 Currant guns are all conversion/ i.e. compressor guns.  First gun was  turbine.  That actaully was slightly worse with more overspray.. Plus I'm not sure if it was because it was new or becuase the technique is dramatically differant but the quality of the finish with the turbine gun was simply lousy..   Too much orange peel..


  Luckily I sold it before it had much wear on it because 6 months after I sold it the turbine died.

(post #81125, reply #30 of 58)

Orange peel is not the fault of a turbine, it is the AIR CAP used and the finish , humidity, flowout, film thickness and temperature.  A turbine can also be throttled down if it is too much volume, but the temp of the air coming out is still as high..and the guns can get warmer than comfortable to hold..again,a  GRAPHITE AccuSpray gun body doesn't do that. Air cap and needle..needs to match the viscosity of the fluid..either a Ford or Zahn cup is used.


You didn't get enough training from a pro, if you had such terible results..really. It take a knack, being so different from conventional HP guns.


Spheramid Enterprises Architectural Woodworks


"Success is not spontaneous combustion, you have to set yourself on Fire"

www.richmondrenovationsandrestoration.com  

(post #81125, reply #27 of 58)

I used to demo and sell accuspray guns and apollo turbines, and yes, you can and will still have overspray, just not near as much as a conventional gun.  Common sense still prevails as to using an explosion proof spray booth. Both for safty and quality of the sprayed surface.


We distributed Hydrocoat waterbased finishes and our selling points were the non flam strengths, for prisons and schools..and that hydrocoat could be used in an occupied hospital, with out the effect that solvent based finishes could have.


But again, if you expected NO overspray or 100% Transfer efficiency, the only way to do that without a brush or roller is electro-static or dip. Wood doesnt take a neg charge real well tho'.



Spheramid Enterprises Architectural Woodworks


"Success is not spontaneous combustion, you have to set yourself on Fire"


Edited 2/4/2008 12:53 pm ET by Sphere

www.richmondrenovationsandrestoration.com  

(post #81125, reply #29 of 58)

Sphere, 


   That's my problem! I hooked the negative side up to the wood not the positive side!


<  Big Grin >

(post #81125, reply #39 of 58)

>>> But again, if you expected NO overspray or 100% Transfer efficiency, the only way to do that without a brush or roller is electro-static or dip. Wood doesnt take a neg charge real well tho'.

Maybe that's why they brought out that "Iron Wood" line. So you can powder coat wood...

(post #81125, reply #35 of 58)

Frenchy


If you were getting a lot of overspray with your HVLP then you did not have it set right! NO IF ANDS OR BUTTS ABOUT IT! I don't care what any tech was saying to you over the phone, he couldn't see your settings so how the hell would he know if you needed to turn the knob 1/4 turn one way or the other?


I don't know if you are using a true HVLP or one that hooks up to a compressor. I have no experience with the later but when I got my hvlp and started playing with it I was getting a nice cloud in my garage and thinking wtf, why all the overspray? Played around with it trying different settings and finally started shooting without the cloud of dust and the hardy Hi-O-Silver, I had finally got the setting close to right, trick now was to duplicate my experience.


Took awhile but I finally got the knack for setting the gun and I have cut down on my overspray tremendously, don't know if I'm 100% dead on but I'm getting pretty good results none-the-less.


NO tech in the world can tell you over the phone whether or not your gun is set right, that man/woman has not been invented yet!


Doug

(post #81125, reply #42 of 58)

Doug U 


Where did you get the idea it was over the phone?  I didn't say that.. I got the factory rep out to my place and he confirmed that I was shooting it correctly. The statement he made regarding overspray was to my face.   I  had the right pressures and the paint was properly thinned..  (first time I'd used a flow meter instead of judgement) 


  As I said the over spray is less than the old high pressure guns, you don't get the bounce off effect  but it is still not completely free of overspray.. others have chimed in here to confirm my statements..


   I did get rid of the old turbine powered system  (luckily for me)  and today both of of my guns work off the big main compressor which I have dialed down to the correct inlet pressure..  The over spray with either system is about the same..


 

(post #81125, reply #44 of 58)

Frenchy


 


Where did you get the idea it was over the phone?


Thinking that I'd made a major goof somehow I called up the Devilbus rep and asked him over. 


 Sorry, All I read was the "I called up the Devilbus rep" part. My mistake.


you don't get the bounce off effect  but it is still not completely free of overspray.


Yes, I agree that there is overspray. Just not as much as an airless, at least in my experiences. I cant speak about the hvlp using a compressor because I've never seen it done so .......


Again, my apologies, I need to read the entire post!


Doug

(post #81125, reply #52 of 58)

Doug U 


 No problem I wish I could claim I was perfect in reading everything posted in the internet, I'm not so I won't bust your chops.  At least it caused me to recheck my spraying approach.. at least mentally..

(post #81125, reply #22 of 58)

Well, frenchy maybe everyone here need a lesson on how to successfully leave OSB out in the rain for four years, and how to set the forms for an ICF foundation in under four hours, and how to build ......  

.

(post #81125, reply #16 of 58)

I've sprayed lots of solvent based paint with an HVLP set up. Last Fall I painted some interior doors using latex and it's a completely different animal. Here's what I came away with:

1) The latex has to be thinned more than recommended on the label

2) Floetrol is absolutely needed

3) The air pressure has to be set 25% higher

After thinning the paint as much as I dared, I found the job was still slow going. The results looked OK but it took about 1/2 hour to paint a door and there was plenty of overspray floating about from the higher air pressure (HVMP?).

Most companies formulate latex paints so they don't run easily. This is good when we're brushing a baluster because a heavy coat will stay in place. The viscosity increases if the paint sits undisturbed and I think that's why the stuff is hard to spray with any gun that relies on atomization. Airless guns are pumping the fluid through the nozzle and that lowers the viscosity when it leaves the gun.

(post #81125, reply #17 of 58)

Are you using a true HVLP or a HVLP that connects to a standard air compressor. I would guess you are referring to a compressor since you say you increased the pressure. On a true HVLP the only adjustment is on the gun. The two on most are, volume of paint and volume of air not presure of air, On a true HVLP you have a 3/4" hose not a 1/4" hose.

So lets be clear here we seem to be talking about three systems on this tread.

1) a airless sprayer; a pump sucks up paint and forces down a hose out of a pistol with a
ceramic tip.

2) a HVLP that uses for all basic description a vacuum motor, usually 3 or 4 stage (cheap
ones are 2) a one stage, what most shop vacs are, won't work. A stage is just a fancy
name for how many turbine fins are ganged on the shaft of the vac motor in series,
each turbine has a baffle between it and the next. Air is fed through a 3/4" garden hose.

3) a HVLP that connects to a high volume high pressure compressor and the air is feed
through a 1/4 hose. In theory this is supposed to work never used one. It might work
if you replumbed the compressor to all 3/4" pipe with a 3/4" regulator that you can turn
down to about 8 PSI with no surge every time the compressor turns on. Yes there are
guns that attach to 1/4 hose but from what I heard they do not work well. You would
probably need a 80 gallon tank either way. Not too portable.

Wallyo

Edited 2/4/2008 1:37 am ET by wallyo


Edited 2/4/2008 1:56 am ET by wallyo

(post #81125, reply #21 of 58)

"Are you using a true HVLP or a HVLP that connects to a standard air compressor. I would guess you are referring to a compressor since you say you increased the pressure. On a true HVLP the only adjustment is on the gun."

I have owned both. I first started with an expensive ($1K) HVLP system with the turbine compressor and $300 guns. I liked the nice warm, dry air the turbine produced, but the epoxy and PU paints I sprayed soon ruined the guns and the turbine blew up about three months out of warranty.

After that I switched to a conversion gun that uses 40 PSI air from my big compressor. This set up works great with the caveat that you need a two-stage dryer and filter to keep all water and water vapor out of the gun end. After going through several expensive, name-brand guns, I switched to the $70 cheap-o units and they work just as well.

The trade off in HVLP is finish quality versus pressure. Very thin paints can be applied at "normal" HVLP pressures (8-10 PSI at the nozzle) with a good finish. As viscosity goes up, the quality of the finish declines unless the pressure is increased. Of course higher pressure means more overspray, and that sort of defeats the purpose of using HVLP in the first place.

Manufacturers recommend a bigger tip when spraying latex with HVLP because that's the only way to achieve decent volume out of the gun with a normal pattern. But IMO the bigger tips produce a coarser finish and I'd rather take a little longer than have something that looks like it was done with a hopper gun.

Bottom line is the claim that HVLP has "little or no overspray" is an exaggeration and it shouldn't be the main reason to use that type of system. There is overspray, just not as much as with a traditional gun. The biggest advantages for HVLP are that it saves money with expensive paints and the turbine systems largely eliminate problems from condensed moisture on sensitive finishes.

(post #81125, reply #24 of 58)

TJK


 well said,, that's exactly been muy experiance..

(post #81125, reply #25 of 58)

It sounds like we pretty much agree my post was not solely aimed at you, but to novices who might be reading this post and not realizing that there are two styles of HVlP's. If you still have your traditional system it probably has a ametek turbine you could probably replace it by going through Graingers or a vac supply house cheaper then through the manufacturer of the gun. If it is not an Ametek they should have one that would fit the motor turbine are pretty universal.

The only paints or finishes I use are water base so never had any experience beyond that.

As to overspray I have found that anything that becomes airborne settles as a dust and wipes off pretty easily. But I live in a very dry climate that may have something to do with it.

Forgot to add I would ratter put on two to three light coats then one heavy coat of paint.

Wallyo


Edited 2/4/2008 12:39 pm ET by wallyo

(post #81125, reply #31 of 58)

This is very helpful discussion for a first-time paint sprayer.  You mentioned that a cheapo unit works fine, and the other posters say only use the $700 version. 


What model do you suggest I purchase based on your experience with the units you have used.  Lowes sells this Spray Tech unit at $300 and appears to be an entry model for HVLP latex spray.  Do you think this would work for my trim project in 6000 sf house (and 37 doors)?  I'm also concerned that it may dry the paint and clog the gun as you mentioned.


Which tip size do you suggest using?  There's lots of references of "big" and "small" tips but to a newbie like me, it's a little foreign.


Also, you mentioned straining often.  Is there a particular cloth or material you strain this through? 

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(post #81125, reply #32 of 58)

From what I can see, the Spray-Tech looks like an airless sprayer, not an HVLP system. HVLP requires compressed air from either a turbine (low pressure high volume) or a regular high-pressure compressor that is used with a conversion gun that "downshifts" to lower pressure at the gun.

When I was talking about cheap-o, I was referring to the price of the spray gun.

(post #81125, reply #33 of 58)

I think you got two or more posts combined in your question as for straining I use cone strainers usually .15 cents each. In a pinch I have used my wife's old nylons too.

Flotrol will help with the paint drying too soon.

As for tip whatever the manufacture of the gun recomends for latex acrilic. Most guns out of the box have the correct one for paint.

TJK I think was referring to a cheapo conversion gun ( one that hooks to a compressor).

To me the attachment you posted is not an HVLP but a airless sprayer.

Wallyo


Edited 2/4/2008 1:33 pm ET by wallyo

(post #81125, reply #37 of 58)

Yikes!!!  I'm glad you guys caught that the Lowes product is not an HVLP.  But I'm also surprised by the one quart-size spray can on the HVLP guns.  How long of a strip of crown moulding can one paint with a full can?  I hope I don't spend all my time refilling the paint can in this 6000 sf house.  Based on all this advice, here's what I am planning on doing.  Hope I'm reading all your messages correctly:


* Rent an HVLP gun from local rental shop.  They tell me it's a professional gun that costs $3000 and professional painters rent them for trim works.  This will take the equipment issue out of the equation, leaving only the "operator" as the deciding factor on the quality of spray.  I guess I will spend the first hour experimenting shooting out primer as first order of business.


*  I will crank the heat in the house to 68 degrees, crack the windows open for air flow to encourage faster drying.  I guess it wouldn't matter because I wouldnt be able to get around to a second coat until the next day at best anyway with 37 doors to do.


* I buy the Sherwin Williams Proclassic in 5-gallon bucket.  Not sure how many gallons I would need for this size of house.  I will pour it out to a 1-gallon can through a strainer (where does one buy such a mesh?).  I will then transfer from the 1-gallon can to the spray can, add in the dry retardant material, and start spraying. 


* Question:  I will stage the house so that the gun is in constant use.  How long do I have between stops before I have to clean the gun?  If it takes me 15 minutes to take a door down and stage its spraying, is the gun still good?


* If there's a cloud of fume, that means I have "[JOBSITE WORD]pit error" and equipment needs adjustments as it shouldn't do that.


Attached is a picture of the kinds of moulding and trims I will be painting with the HVLP gun.  Consider this a "before" picture.

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(post #81125, reply #38 of 58)

You will never get that ProClassic to spray without thinning with water at least 10 percent.  Try it at 10, fool with the settings, see of she flows and coats.  You may have to go as far as 15.


Floetrol is not a thinner.  It is not added at 10 percent.  It can aid a little in leveling (that is what is happening when the blast of microdrops placed on the surface flow out into a smooth film) but it doesn't lower viscosity.


Be sure you are getting at least a 4-stage machine, if you are not doing the gun/pot/compressor setup.


Doors, flat, per room, huh?  Over 30 of them?  I'm surpised you didn't bite on the all-doors-painted-painted-upright-both-sides-in-one-place method.

 

"A stripe is just as real as a dadgummed flower."

Gene Davis        1920-1985

(post #81125, reply #46 of 58)

Gene, after thinking about it more, masking the hinges and painting the doors in place seem like a better idea than taking them down.  I thought there was some federal laws preventing this because the idea is so simple, but no one does it that way.  Everyone carries to the garage.  Why?  I would rather mask plastic surrounding the doors and paint on the hinge. 


Added to my list of painting to-dos now include:


* Thinning 10% with water.  More if needed.
* Add Flotrol to slow drying.
* Confirm rental machine is a 4-stage turbine and not a gun-compressor arrangement.


BTW, I am really surprised to have this much disagreement on HVLP versus airless.  Everyone is so convinced their gun works best for them.  I think it comes down to trying it out for myself and see how it works.