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Shop Paint Booth - Air Filtration and Drying

bkervaski

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Testing
I'm setting up to paint my next project and was looking for input on my plan:

- Devilbiss Prolite HVLP
- Quincy 60 Gallon 2-Stage Compressor
- Maxline system (at least 50 feet with at least 2 water traps)
- Devilbiss QC3 Filter and Dryer

As far as paint booth, I have an air conditioned 12.5 x 30 temporary enclosed area with appropriate air flow and exhaust.

I live in Alabama, so if I want to paint past 6am during the summer humidity is a huge consideration and was leaning towards the Devilbiss CT Plus 5-Stage system vs the QC3 but it's probably overkill and obnoxiously big.

This will be my first big paint project, I'd rather my skills be the limiting factor and not the setup, advice appreciated :)
 
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I'm setting up to paint my next project and was looking for input on my plan:

- Devilbiss Prolite HVLP
- Quincy 60 Gallon 2-Stage Compressor
- Maxline system (at least 50 feet with at least 2 water traps)
- Devilbiss QC3 Filter and Dryer

As far as paint booth, I have an air conditioned 12.5 x 30 temporary enclosed area with appropriate air flow and exhaust.

I live in Alabama, so if I want to paint past 6am during the summer humidity is a huge consideration and was leaning towards the Devilbiss CT Plus 5-Stage system vs the QC3 but it's probably overkill and obnoxiously big.

This will be my first big paint project, I'd rather my skills be the limiting factor and not the setup, advice appreciated :)

A few comments:

* Personally, I am not a big fan of HVLP guns. These were originally developed to meet environmental requirements - not because they worked better. These days, you can also buy "compliant" guns which meet the environmental requirements in some states but aren't technically HVLP guns. I have 3 guns - 2 Sharpe HVLPs and a Devilbiss compliant. I use the Devilbiss for all the finish work.
Honestly, every painter has his favorite gun (favorite because he has used it enough to get proficient with it). The trick is to practice enough with both the gun and the paint system you are using to get yourself "dialed in".

* Keeping moisture out of the air supply is essential as you have figured out. I am just north of you in Huntsville - so I know about dealing with Alabama humidity! The compressor, lines, and regulator/filter/dryer you mention should work fine. In fact I believe the QC3 is the same one I used. I also used "final filters" that attach to air inlet on the gun to catch any water that might get through. Never had any water issues during the paint of the RV-7 or cars before that. Nothing wrong with going for the fancier system though. Water spraying out with your paint will definitely ruin your day!

* I would recommend you include a small pressure regulator with gauge that attaches at the gun. My process was to set the regulator on the OC3 to some number a good bit higher than my desired spraying pressure. I would then set the actual spray pressure on the gun regulator. More convenient to adjust on the fly and is more repeatable as you change air hose lengths/diameters.

* You say you have "appropriate" airflow and exhaust in your painting area. Is this based on industry standards for paint booths or ?????. IMHO, the airflow/exhaust issue is mostly about visibility and over spray issues. I assume you are planning on a fresh air system for breathing (Hobby Air or equivalent) rather than a filter mask? Some paint systems require a fresh air breathing system if you want to KEEP breathing!

* Good inlet and outlet filters are a must - tacky inlet filters to catch dust, etc, and outlet paint arrestors to keep your downstream fans, ducts, etc from getting clogged with paint. Actual paint booth filters are easy to get online and not terribly expensive. Much more effective than your typical furnace filters.
Biggest debris issue (at least in Alabama) is BUGS. Avoid painting at night unless you have a clean room for a paint booth. Some little sucker will always find his way in to your carefully closed booth and into the paint!

* There is no such thing as too much light IMHO - particularly side lights that illuminate the vertical surfaces you will be spraying. Painting is a bit like welding in that you will have a hard time doing a good job if you can't see the work.

My 2 cents based on my painting experiences. I am full of opinions (like everyone else) :D. Feel free to contact me if you like - glad to discuss further.
 
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I’ve tried expensive guns and cheap Harbor Freight HVLP guns. I find the more expensive Harbor Freight guns give me the best result (but I run them at a higher pressure - so much for HVLP).

I built the paint booth and use an old attic fan for exhaust, inlet filter uses a panel of standard furnace filters.

Dry air is critical. I use this tub full of water and block ice. It has done the job very well. Just remember to drain it every hour or so.

Side note: If you have any decent air flow air conditioning will be sucked out in a few minutes.

Carl

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Gun is your choice high dollar or cheap. You will be able to paint if you are able to paint. I have a bunch of them. Most expensive is just north of $800.00
The air dryer is mandatory,
A big bonus is if you are able to put a second tank to let air cool and reduce the compressor run times.
I have an 80 gallon compressor outside in a small enclosure, piped to a 120 gallon tank (Craigslist for $100.00) inside then piped to the Maxline system in my hangar.
I also have an air dryer on my painting air line.
No problems with water here,
Had those in the past, so I went overboard on the dry air system.
A couple of fish eyes from water in an otherwise perfect job really sucks. OH YA THEY ARE USUALLY ON TOP
Art
 
First, let me say that I paint for a living and I’ve painted over 300 RVs.

I’ve painted in really nice booths and basic barn type hangers. A nice relatively clean space is what you need at a minimum. Try to have it as un cluttered as possible when your painting. You’ll be concentrating more what you are doing at the moment than trying avoid any hazards. The makeshift booth pictured above can work well. You can even upsize the concept to fit a whole airplane. I’ve done Lear jets and Citations in similar setups.

For air you’ll want at least a 5hp compressor with an 80 gallon tank. The Devilbiss QC3 or similar is bare minimum for a water filter. If you want to step up, the Devilbiss Cam-Air CT30 is a good choice. I usually run my air pressure at 120 at the wall and use the “cheater valve” on the gun to turn it down from there.

A darn good spray gun for not a lot of money is the Devilbiss GPi. About $250 from spray guns direct. The new GPG 7E7 is also very nice for about $350. 3M PPS cups are the best thing since sliced bread. If I’m not using my pressure setup, that’s what I use.

Painting in the morning is good. Your mind and your body are fresh and you are full of energy. Don’t worry about humidity to much. Modern urethanes like a little bit of moisture. Try to have it below 85% while your painting and for a couple of hours after.

Buy a good respirator. Different brands fit differently. Find the one that fits you best. Also get a paint suit and gloves. You want to keep you and your airplane clean.
 
Watch that compressor carefully. My 5 hp 60 gallon super-quiet Quincy two stage burst into flames just beyond the warranty - and the motor is as expensive as the whole rig, almost. Bad compression release is suspected: the thermal CB in the motor will protect the heavy-duty main windings but not the light-gauge startup winding from overload. I dumped a household BC fire extinguisher on the thing and was fortunate not to get that corrosive powder all over the RV in the process.

... can happen to any compressor, but I just know the Quincy is vulnerable. I finished the build with a pancake compressor but will probably rebuild the Quincy if I paint it myself. Local motor shop said the motor carcass was uneconomical to repair.
 
I'm setting up to paint my next project and was looking for input on my plan:

I'm a mediocre painter at best, but my belief is a good painter can get excellent results with mediocre equipment, but the best equipment in the world won't produce good results for a mediocre painter. And the only way to get better is to practice and learn from your mistakes.

Your plan should include buying at least a quart of the exact paint you plan to use, then planning multiple spray sessions to learn how to paint convoluted surfaces with your gun and that paint. Even better, buy a quart or two of the cheapest urethane you can find (Summit, Kirker, Eastwood) and practice with that first before you even get around to practicing with *your* paint.

With your booth, one key is to make sure incoming air is filtered and is moving at low velocity coming into the booth. That'll keep the incoming air from carrying a lot of trash into your paint. Your exhaust system can have high velocity if that's necessary to move an appropriate amount of air. Exit air won't put dust into your project. Filter your exit air to capture most of the overspray before it lands on whatever is downwind from your booth.

Good luck and remember that you can correct most painting errors by block sanding and buffing.
 
I'm setting up to paint my next project and was looking for input on my plan:

- Devilbiss Prolite HVLP
- Quincy 60 Gallon 2-Stage Compressor
- Maxline system (at least 50 feet with at least 2 water traps)
- Devilbiss QC3 Filter and Dryer

As far as paint booth, I have an air conditioned 12.5 x 30 temporary enclosed area with appropriate air flow and exhaust.

I live in Alabama, so if I want to paint past 6am during the summer humidity is a huge consideration and was leaning towards the Devilbiss CT Plus 5-Stage system vs the QC3 but it's probably overkill and obnoxiously big.

This will be my first big paint project, I'd rather my skills be the limiting factor and not the setup, advice appreciated :)

Bill, I think you will get the dryer thing down, but when shooting, nibs and debris always seems to be the biggest challenge in a home build booth. No booth is immune. I worked in the building of a body shop in Opelika for a while in the early 70's. Don was equal to the best shooter I have ever seen and could shoot a glassy enamel paint on a car that had no nibs and as you know, enamel is too soft to wheel. He would leave he would leave the car shop and blow it off, and hose/water the floor. Then go eat supper and come back at 7-8PM and tack ragged the car for settled material, keeping the floor wet. Then once done, no fans or anything, just leave it until morning, paint fog and all. The result was amazing and I am quite picky about paint quality. Oh - watering, just from the hose, no nozzle or spraying just the stream or tiny balls of water floated on the car. Very bad for fish eyes. This seemed to work all year, but I don't know what he did when it rained. Maybe just heated the garage.

Hope this gives some ideas that will serve you well. I assume you have a good externally supplied breathing mask for the modern stuff.
 
A few comments:

* Personally, I am not a big fan of HVLP guns. These were originally developed to meet environmental requirements - not because they worked better. These days, you can also buy "compliant" guns which meet the environmental requirements in some states but aren't technically HVLP guns. I have 3 guns - 2 Sharpe HVLPs and a Devilbiss compliant. I use the Devilbiss for all the finish work.
.

I also have a Devill Biss compliant gun and it does a GREAT job laying down smooth clear coat. Highly recommend one.
 
Good luck and remember that you can correct most painting errors by block sanding and buffing.

+1

I have painted several cars and 2 planes in my garage. No booth. It is just too limiting for me. I clean the garage well and lay tarps on the floor and hang them to protect stuff. I wet the floor with water, ground the parts being sprayed to an earth ground (spraying creates a lot of static electricity and the metal parts develop a charge that attracts dust) and use tyvek body suits (I have been told by some very experienced people that most dust problems originate from the sprayers clothing, not the surrounding air). I surprisingly get a minimal amount of dust. However, there is enough dust that block sanding and buffing is required after the final coat, if you are looking for quality. However, if this is your first spray job, there is a good chance you will need this step anyways to work out flaws that are inevitable for a new painter.

The most painful flaws are runs in clear or Single Stage paint (really just clear coat with pigments). Suggest significant research to understand how/why/when this happens and take time to mentally plan out how you will lay down paint in complex areas where managing overlaps is difficult.

Larry
 
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Consider how you will exhaust the paint mist. I built an elaborate booth including an explosion-proof 220v exhaust fan. Turns out even though it was variable-speed it would only run at full speed. Very effective but it created so much suction it was a challenge to keep dust out of the air, as it was pulled in from the next county. Plenty of folks have used Walmart box fans but after a buddy set his fabric wing on fire from a static spark while spraying Aerothane I'm leery. It's the main reason I would use a water-based system next time.

Dust-wise, I had better luck with a previous project in a garage using a couple of small box fans that blew in through furnace filters, so the booth was at a positive pressure. None of that was isocyanates. You don't want those leaving the booth near your house except through an exhaust fan.

A side benefit of the water traps is your air tools stay dry.
 
It's a waterborne system.

Yep, the box fans and a filter are what we plan on using.

Good point on sucking all the AC air out of the shop.
 
Consider how you will exhaust the paint mist. I built an elaborate booth including an explosion-proof 220v exhaust fan. Turns out even though it was variable-speed it would only run at full speed. Very effective but it created so much suction it was a challenge to keep dust out of the air, as it was pulled in from the next county.

This is why you create a large inlet area/filter. That will keep the air velocity down on the intake side and bring in less dust.
 
The small parts booth at work has 5 24 inch by 24 inch intake filters and two exhaust filters of the same size. The single exhaust fan is in an 18 inch diameter tube.
 
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