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I have done very little spray gun work. I have talked to people that spray nitro that say they leave the guns loaded for a while because the solvent opens it back up. Sort of makes sense. With the water base group of finishes, if you are spraying every 30 mins, what do you do with the gun? Are you cleaning it every time, or is that quick enough that a few quick bursts and it shoots well again? Seems like even water clean up would be tiring if you have to do it every time. I know technique just comes with practice and gun adjustments and lots of practice wood, but the back side of it all, the maintenance of the equipment doesn't get talked about much, it seems.
Thanks for all of the help.
Donovan

Seems only fitting that I reply
I've found the best procedure between coats is
disconnect air & drain lacquer in gun back into cannister
reconnect air & spray water only (at some point, fluid in gun will run clear- water only)
remove tip from gun & drop into jar of hot water
put gun back on cannister
When ready for next, retrieve tip ... scrub briefly with toothbrush ... replace on gun.
This seems to keep anything from clogging up, which it can do with WB quick jell time.

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Dave
Milton, ON

Hi, Donovan. Archtop builder Dave does it pretty much the way I did it. It's not such a hassle, and in any event it's not as big a hassle as cleaning a clogged gun. I would only add that when you're putting the spray equipment to bed for the night, go through Dave's procedure, then blow air through the gun and all parts of the gun and cup that you can reach with your hose, remove the needle and gently wipe it dry. I laid my gun parts out on a paper towel in case anything that I missed needed to air dry. When finally finished with the project, I also lubricated the needle with petroleum jelly (a tiny dab wiped on, and then off). Then, when preparing to shoot the next project, just wipe the needle with a little alcohol to remove any petroleum residue.

Umm - I'm a little confused. Are you asking what to do with the gun between coats, shot 30 minutes apart? I certainly wouldn't drain the gun in between coats. Over night (or longer) , yes, drain, clean, dry the gun. When I've been shooting subsequent coats - (and I wait a bit longer than 30 minutes), I leave the gun loaded. Caveat - I'm not using EM6000 - I use KTM9. When having occasional problems with some clogging, I've drained the gun and shot a bit of DA (be careful - don't want a spark nearby) then reloaded the waterbased finish, shot some waste until the finish is shooting as I like it (and until any residual DA is through the gun) and then apply another coat.

I do find shooting water-based finishes to be pretty tricky - to get the right thickness of finish on the guitar without runs. I add a bit of DA to the finish that I use (not much - maybe a teaspoon full per pint of finish) and find that that makes it lay ou easier.

Corky, I gotta' say ...at least with EM6000 and USL ... the above procedure takes under a minute and idiot-proofs the whole thing. No DA involvement. (Just something else to screw things up, IMO) But then EM6000 sprays beautifully without runs....really user friendly. Could I get by without draining the gun & flushing/blowing out?? Yeah, probably 95% of the time. In my experience, the tip procedure is essential. Never tried the petroleum jelly Patrick, although making sure everything's dried out before ass'y is a good point.

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Dave
Milton, ON

Donovan,

I've been using EM6000 for several months now and I have learned how to make it work for me.

Unlike nitro and other solvent-based coatings, in a water-born coating, there is no solvent to keep things "open", so advice about how to handle your gun between coats that you get from an automotive paint supply house is somewhat askew. First of all, I think 30 minutes is too long to leave EM6000 in your gun without flushing it. If I am going to do some painting with EM6000 where there will be more than 15 minutes between coats, I do flush my gun. I have had very good luck with a 15 minute down time, but longer than that, now way. BTW, I use a 4-turbine Apollo HVLP, so my system tends to get a little hotter at the delivery end making coagulation a greater problem than a compressor system.

The good news is that all the EM6000 flashes off in less that 15 minutes, even when I have to add retarder during these highly humid, hot days. Obviously, after 15 minutes, the lacquer is still soft and you shouldn't touch it with your fingers; but it is stable enough for further coats. EM6000 is more sag-free than other water-borne lacquers I have used, so I lay it on pretty thick.

I found that a second paint pot is an excellent investment. Sometimes between coats when there is a possibility that I might be delayed beyond my 15-minute, I use that second pot to flush the system. It's not really a big deal, to open your gun, drain the finish out of your pickup tube and then move over to the second pot containing hot water and a few drops of dishwasher detergent. Then spray until you have purged all the EM6000 from the gun.

Tom

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I spent most of my money on women, guitars and whiskey, the rest I wasted.

Given the 30 minute interval, I do nothing.

But when I am done, I blow HOT water through the system (after draining EM).

Seems to me acetone is a better solvent for uncured finish. Blow that through after hot water (out the garage door!). Then, dissemble the gun and use high pressure to blow everything out. Wipe everything with a soft rag. Before using again, I blow hot water through the gun to make sure its working properly.

Mike

Yo, Dave,
That trick of lubricating the needle with petroleum jelly is something I found on the web about basic spray gun maintenance. It might be overkill, but I figured it couldn't hurt, so I did it with no qualms. I think there are probably more people shooting nitro-based finishes than water borne finishes. Those finishes strike off real fast. Those folks can probably just shoot a little lacquer thinner at the start of each new job and, presto, their gun is ready to go. As we are well aware, water doesn't strike off nearly so fast, so even though I was dealing with stainless steel parts, I figured it couldn't hurt to go the extra steps to protect to equipment (air blasting, lubricating, etc.) It costs about fifteen seconds to wipe the needle with alcohol (which immediately strikes off) when using it for the next project....so....you know....better safe than sorry. That's just my way.

Patrick

I've done about 40 guitars with Target water bournes and the last 15 or so with EmTech 6000. IMO the EmTech is as easy as any of the others and most importantly has wonderful burn-in properties and is generally as much of a "no-muss" finish as there is out there. Absolutely no witness lines and that makes the inevitable last minute touch-up a no-brainer. As for leaving the finish in the gun, I've not had any problems whatsoever with the following schedule.

I generally spray over a 3 day period with 45 minute intervals between coats (I spray 20 coats on the back & sides and 14 on the top). My coats are very light and pre-sanding thickness on the B&S is about 6.5-7.00 mil and about 4.5 on the top. I shoot for about 3.5-4 final thickness on all surfaces) I don't clean the gun between coats. I do run a little DA through the gun after a session and leave some in the gun overnight. I then spray a flash coat of DA at the beginning of a new session.

If you're going to exceed 12 hours between the end of a session and the next one, then take the gun apart and clean it. Otherwise, I've found it unnecessary. Good luck!

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Jimmy Caldwell
http://www.caldwellguitars.com

I don't clean the gun between coats if I am only shooting 3 or 4 coats in a session. I'll blow air through the gun between coats then disassemble and clean only at the end of the session. I drop the cap and tip in a small jar with dna, and leave it there until I shoot again.

Ken

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http://www.casperguitar.com

I've used EM6000 for the last 6 or 7 guitars and follow a plan similar to Ken and Jimmy where I will leave the gun loaded between coats during a three coat set. I will wrap a wet rag around the air inlet at the top of my gravity feed cup to keep the air inlet from clogging and will wipe of the air cap and tip. But haven't had any adverse affects from having the finish in the gun for 3 or 4 hours. At the end of the day I clean the gun and all seems well the next day.

Kent

Thanks for all the input. Great that another Stewart jumped to respond first. As with everything else is seems there is no absolute way to do it and everyone has their "way". This gives me more confidence to work with and find what works for me. I love all of the help.
Donovan