Author Topic: Sprayers and thinning  (Read 13832 times)

Sparky

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Sprayers and thinning
« on: April 22, 2006, 04:57:59 PM »
Thank god there is a forum for painting.  Anyway, about a month ago I bought an air compressor to help me lay a hardwood floor.  Never owned a compressor before but I own about every other tool imaginable so with the prospect of painting multiple doors in the near future I decided to pick up a gun.  I grabbed the Porter Cable PSH1 HVLP with a 2.2mm flow setup.  I get a can of interior latex put some in the cup and.... nothing.  so I thin it with a little water (10%) with not much improvement.  Long story just a little bit longer, I continue to thin it down to the point where it will at least spray, but atomization is almost impossible.  Well at least I haven't gotten there yet.  I bought the gun to make trim and doors a little more enjoyable but if I have to thin the stuff down 50% then I'm not bothering and will stick to a brush.  I like spraying because the end result just looks nice, so if anyone has a special formula for cutting latex, I'm all ears.  Thanks in advance.  - Jim  

the PAINTSMITH

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Re:Sprayers and thinning
« Reply #1 on: April 23, 2006, 06:27:06 AM »
Jim, I have NEVER seen good results with latex through an HVLP or cup gun...Oh, I'm sure you'll find those that have and even swear by it, but the solvent used for latex is water, and water is nearly impossible to predict through a device using that small an orifice with that low of pressure...The paint would have to be thinned to a virtually unuseable consistancy, meaning a new definition to the term "multiple coats"...And the atomized paint will want to start to dry as soon as it hits that air jet at the tip.

...But you shouldn't be getting nothing...Check all the ports and airpaths for blockage (latex will dry fast enough to cause this), and look for any factory labels or tags that you might have forgotten to remove...

Cupguns and HVLP were developed to deliver solvent based coatings. If you get one to work well with latex I commend you...I worked with a painter once, who on his first attempt at working with an HVLP tried to paint doors and trim with a latex semigloss enamel...The first couple of jambs didn't look too bad, but once the air started to get warm the paint came out of that gun like silly string...Took an hour to clean out too...

...Wish I were more help

Offline brushworks

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Re:Sprayers and thinning
« Reply #2 on: April 23, 2006, 09:44:00 AM »
I have sprayed Cabinet Coat (Urethane Acrylic) and Pro Classic using a HVLP sprayer.

I used 16 ozs. of Flood Floetrol per gallon and 8 ozs of clean water through a #12 air cap and needle. A circular spray pattern is required for even layered coverage.

It worked..okay, but not commendable from a professional standpoint.

The clean-up and back prep took away from the accomplishment.

Stick to the brush. It's much more satisfying.

Michael
When asked, "what do you do for a living?" I reply, "I market the world's best windows and doors."

Offline rmichael

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Re:Sprayers and thinning
« Reply #3 on: April 23, 2006, 09:44:17 AM »
Sparky,
I think the key to spraying latex is simply getting the paint to the tip. The cap size, air and material adjustments will do the job once the paint arrives at a constant feed.
It seems that now days EVERY spray gun claims to be an HVLP, which of course they are not. Even conventional guns are now claiming HVLP status. A true HVLP uses a constant flow of air from a turbine ( or motor source ) and can be fitted with different sized needle and cap sets that can be matched to the coating being used.
Since oil based paints are rapidly becoming obsolete, spray systems are being marketed ( and engineered ) to handle the more heavy bodied latex coatings. It is just a matter of finding the best match.

I have achieved very good results using an air compressor and a remote (paint) pressure pot with a conventional gun ( minus the cup ). I have also had good results using a top cup gravity feed conventional gun with an air compressor. As with any spraying you will have to thin the material some, and with latex always use a conditioner like Floetrol or XIM.

Best of Luck.
Pro Painter 30 years ~ Down East Coastal NC

"Hell Son, It's always been about the work."

Offline CarlThePainter

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Re:Sprayers and thinning
« Reply #4 on: April 23, 2006, 02:55:52 PM »
Just buy an airless rig...then you will never have to thin anything ever again.

the PAINTSMITH

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Re:Sprayers and thinning
« Reply #5 on: April 23, 2006, 04:19:52 PM »
Carl's right Jim. Even a consumer grade Wagner will give you better results.

Offline rmichael

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Re:Sprayers and thinning
« Reply #6 on: April 23, 2006, 08:10:21 PM »
Jim,

Porter Cable PSH1 is a gravity feed (top cup) gun. I use the same type of gun to shop spray cabinet doors with latex enamel, and get beautiful results. You should not have to reduce the paint more than 20% with a 2.2 cap set, but you will still will need Floetrol or XIM.

Open up the air and material, start your pressure at 45psi. Prime the cup with water (dump in-trigger once-and dump out) pour in the readied paint and adjust everything from there, including the air pressure. Be sure to check, and open, the air flow inlet knob located at the heel of the gun.

best of luck..  
Pro Painter 30 years ~ Down East Coastal NC

"Hell Son, It's always been about the work."

Sparky

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Re:Sprayers and thinning
« Reply #7 on: April 24, 2006, 12:10:26 AM »
Hey guys, thanks for all the responses.  Luckily I'm not under too much pressure to get this done.  I'll try working with the floetrol a little and if I still don't like what I get, hey i can always brush right.  Thanks again, and if any of you happen to be in the Greater Portland area (Maine) and happen to have a brush on you don't be afraid to stop on in.  We'll be painting throughout the summer  ::)  - Jim

Offline Crusher

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Re:Sprayers and thinning
« Reply #8 on: June 23, 2006, 10:46:34 AM »
Jim, I have NEVER seen good results with latex through an HVLP or cup gun

Yikes!  Most of our painting crew took time off to do a side job but left one individual here to continue painting the exterior with latex.  He has been using his personal HVLP sprayer and has completed our front doors as well as window trims (the main crew used a pro sprayer for the body of the house.)  Currently, his work looks excellent.  But as the temps rise and the paint cures, should we anticipate any issues?  Is this an issue that should be raised now before any problems appear?
« Last Edit: June 23, 2006, 12:15:43 PM by Crusher »

Offline rmichael

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Re:Sprayers and thinning
« Reply #9 on: June 23, 2006, 01:14:56 PM »
I believe Eric referred mainly to the HVLP application process, if the finish looks good after it has dried, then the painter must have the application down pat,... and that is the way it should stay.. at least for the life of the paint....   :)
Pro Painter 30 years ~ Down East Coastal NC

"Hell Son, It's always been about the work."

Offline Crusher

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Re:Sprayers and thinning
« Reply #10 on: June 23, 2006, 04:10:48 PM »
I believe Eric referred mainly to the HVLP application process, if the finish looks good after it has dried, then the painter must have the application down pat,...
Thanks for confirming, rmichael.  Man, I just love this forum. The wealth of knowledge is comforting. I only wish I discovered this site before our painting job began!
-Mark

the PAINTSMITH

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Re:Sprayers and thinning
« Reply #11 on: June 24, 2006, 02:21:56 PM »
Mark, HVLP's, at least the older ones I've used, begin to push hot air after a short time...Latex paints tend to react adversly sprayed through a hot air stream--plugging orifices and "stringing". If your painter is having good results, don't bother him about it, he appears to know what he's doing...

...Latex formulas are an ever-changing medium, considering the constant badgering from outfits such as the <gulp> EPA...I have no doubt that there are many formulas now that will survive the process by which HVLP and cup sprayers operate. I recently saw a rig in a paintstore that utilizes the same pump for both low-pressure airless and HVLP, though I was so skeptical of it's durability as a viable production machine that I never looked into how it works...

Offline Harmonpa

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Re: Sprayers and thinning
« Reply #12 on: September 29, 2016, 11:56:20 AM »
I know this is an old topic but  there is a complete guide on this topic at the link below which may help with alot of your questions

https://www.pittsburghsprayequip.com/2016/09/29/spray-guns-and-thinner-complete-guide/