Problems with Target em6000 - created 02-28-2010

Ryan, Michael - 02/28/2010.14:35:22
Never waste the challenge of a big mistake

Hello,

I seem to get a decent finish after wet sanding with micromesh and buffing but I would like to get a better finish when spraying it without working so hard. I am looking for perfection tho. if I can achieve it.

I have read everything I can find about these problems on the net. NO help.

I use an asturo eco/sx with the 1.4 tip. I have a porter cable 5 hp small compressor. Room is 79 degrees, humidity 40 percent. I hold the gun at about 8 inches away from the surface to be sprayed.

I am trying the em6000 .

I still get bubbles no matter what I do. They are small bubbles.

I have tried 35 inlet with 22 psi pressure at the gun with the trigger pulles.

I have tried 30/20, 27/18 . Not much change.

Still bubbles.

Tried Warming the finish sightly and seemed to have more bubbles which seemed smaller.

Interestingly, I have few bubbles with the detail cone that comes with the kit.

ALSO, I get runs and sags no matter what I do. I am finishing an OM style steel string guitar.

I have tried varying the opening of the trigger, no help. I really can't go full open - way too much finish.

I usually need about 5 turns from fully closed to get fewest runs and sags possible. Blowing on it with a fan helps the sags to stop propagating.

The runs and sags always come at the waist no matter how I seem to move across the guitar side.

Sometimes the sags wrap from the sides to the top or back.

I have tried spraying less finish volume but it just makes a dry rough finish.

Well, I guess that's enough for now but I could go on. Any suggestions appreciated.

I have the ECO/SX gun and use EM6000. I don't have a gauge at the gun so I measure at the regulator output. I usually run with 40 to 45 pounds pressure with the trigger pulled. I spray about 6 inches from the surface and move the gun rapidly horizontally. I set the fan vertically with a 90 degree pattern centered at the tip and play with the fluid feed and the air feed on a test piece until I get what I want. Every now and then I get a few bubbles but they haven't been enough of a problem that I've gone troubleshooting yet. The bubbles do seem to be new with the last batch of EM6000 I opened. Your temperature and humidity seem to be optimum. I have had no problems with runs or sags--I expect that they have to do with how much finish you're putting on at once. Frequently, I'm able to get an almost glass finish from the gun with this setup. Less pressure gave an orange peel coat--I settled at 40 or just above to get rid of the texture. So, in summary: more pressure, less distance (too far and the finish starts to dry before it hits), and play with the air and fluid volumes on scrap.

How is your guitar held?

Do you spray vertical or horizontal surfaces?

Also, Do you try to keep you cup full. I only will the cup with the amount I need which is usually less than 1/2 of the cup full.

So, you never have runs or sags? Wow!

I hang the guitar so that I'm spraying a vertical surface. I fill with only what I will need for a session--always less than 1/2 cup. The amount in the cup does influence the fluid volume. I said I have no problems with runs or sags. When I get one, I wipe it off and adjust my gun handling so I don't get another. I don't get many and they are infrequent.

Michael, I have to agree with Bob. Just sprayed a guitar with 6000 (first attempt with this) using my cheap touch up gun (no idea of the tip), with none of the problems you describe (helpful, I know!). 40 psi at the tank (no gun regulator), 1 1/4 turns on both air & fluid at the gun, vertical pattern- horizontal passes (50% overlap). I know that if you shake it up, acrylic will froth, but settles down with time. Never had bubbles or sags on the applied coat (I spray 3 then wait 2 days, sand & repeat).

Thanks Dave, but you're right, that doesn't help at all.

I haven't sprayed EM6000 yet (there's a full can in my shop though) but here's an article I posted with my first experience with HVLP spraying Target USL - EM6000's older brother. Perhaps it will help: http://banduramaker.blogspot.com/2009/02/finishing-lessons-from-my-first-guitar.html

Andy,

I do get a very nice finish with a lot of leveling and sanding.

I start with the 1800 micromesh and either go up or down depending. I go to 8000 and buff sometimes 12000 and then buff. Buffing takes about an hour.

Here is a link to my first OM last year - very shiny and nice with the target USL but every time I do one the result does not seem very good until leveling, sanding, buffing. Kind of makes me nervous every time after a lot of work finishing. I don't feel I have the production routine I want to be as predictable as I want.

Sounds like maybe Target put too much wetting agent/detergent in your batch? I have no idea what I'm talking about but thought I'd take a wild guess. I wouldn't hesitate to call them on Tuesday (everyone else calls on Mondays).

Could there be an air leak in your gun that's pushing air back into the paint manifold and making the bubbles inside the gun?

My humble opinion......most people (including myself when I originally started using them) think that HVLP guns are meant to be operated at low pressures so they automatically lock themselves into trying to shoot anything and everthing at the same, low, locked pressure. And bottom line, what happens is that the spray material doesn't get properly atomized which results in textured, uneven, or bubbly coats to name a few. And their first intial reaction is to try to spray it a little wetter thinking that will help it flow out. But it's just laying on more unatomized material and adding insult to injury. I've been spraying for years now (spent a good portion of my life as an auto painter) and one thing I've figured out is that most if not all HVLP guns require more air pressure than the manufacturer recommendation. Sometimes a great deal more. So my first suggestion would be to gradually increase your air pressure until you really see a significant change in atomization. This will vary depending on what your spraying but as an example, I use alot more air pressure to spray urethane than I do nitro. Requires more pressure to atomize the urethane than it does the lacquer. Also, one other point worth noting......all woods are porous, some more than others, and those pores hold tiny amounts of air. If the surface hasn't been properly sealed and leveled before you start with the finish coats, then that could possibly be causing some of the bubbling as well. How are you sealing these guitars before the finish coats? I've personally started using nitro clear as a sanding sealer also. Long story but let's just say I'm tired of compatibility issues between different sanding sealers and different finishes. Using nitro eliminates all the problems and really doesn't add much to the cost.....actually probably saves me money in the long run not having to worry with any other issues. But anyway...the first few sealing coats of nitro that I spray on any of my guitars will most always have some of the tiny bubbling you refer to. But once completely sealed and levelled, they're completely eliminated. But as I said, that's not a spray issue...simply tiny amounts of air escaping out of the pores of the wood itself.

This project was sealed with shellac, then epoxy, then em6000

I still comment that the CONE doesn't have any problem even at lower pressures but the cap does. I have cleaned the cap with acetone and am going to try higher pressure, less volume.

Dropping down in needle size might help as well. Should've mentioned that earlier. Maybe a 1.2 or a 1.0

I have 2 fullsize HVLPs and 2 touch-up HVLPs along with numerous other regular spray guns and for guitar work and other smaller jobs that require greater detail and accuracy, I get much better results using my touch-up guns. The two HVLP touch-ups that I use both have 1.0's. Not sure what my regular touch-up guns have but they get just as good of results as the HVLP touch-ups do. I will say this. Both of my fullsize HVLP's are Sharpe's. And they are both finicky as hell. In fact, I had to lap the needle and seat in one of them with lapping compounds to finally get it to perform right. Good luck with it. Hope this helps a little.

A number of people have said that shellac over epoxy works but epoxy over shellac doesn't work. Maybe that's it. (Does your sample board show the same problem?)(If not, try to reproduce the problem.)

FWIW, I learned early on to drop the cap of my touchup gun in a jar of water between coats... turned out this was a key for me- little orifaces really clog up using acrylic lacquer.

Dave, I've heard pleanty of anecdotal reports of epoxy over shellac not working, but have never heard anyone speak of problems from their own experience. I personally have used epoxy over shellac many times and have never experienced any problems. It's beginning to become one of my pet peeves.

Has anyone actually had any problems themselves?

From personal experience, the only thing I've run across that won't adhere over shellac is urethane. No matter how I prepped it, the urethane still peeled up very easily when sprayed over shellac. Of course, I was being hard-headed by doing it to begin with since the shellac manufacturer details specifically say not to apply urethanes over it. But me being the bull-headed experimenter, I had to at least try it and see for myself.

>From personal experience, the only thing I've run across that won't adhere over shellac is urethane. No matter how I prepped it, the urethane still peeled up very easily when sprayed over shellac. Of course, I was being hard-headed by doing it to begin with since the shellac manufacturer details specifically say not to apply urethanes over it. But me being the bull-headed experimenter, I had to at least try it and see for myself.

If you want to have good results with Urethane (I assume you mean auto finishes) over shellac, shoot a coat of what ever brand you are using's intercoat clear, which would be a solvent based urethane, it will bond nicely to the shellac. Then proceed with your two part clear. I've had good luck with this and barely adds anything to the cost amortized over a few guitars, plus you can add trans-tints and other toners to do your bursts and translucent finishes to the intercoat without worrying about it goofing up your clear coat.

Nathan, that's basically the method I've adopted for getting past that obstacle with the exception that I started using nitro as the buffer. Since I use amber shellac alot as the center primary color for my burst finishes.....I just tint my nitro and spray directly over the shellac with it. Once I'm done, I can then just topcoat with urethane with no problem. It's rare that I have someone preferring a urethane finish to a nitro finish but there are a few that do so this is how I've dealt with that problem. BTW, nitro will burn in and adhere to shellac like nobody's business without eating or wrinkling.