Hi all,
I haven’t sprayed for awhile and am having trouble getting good results.I am using the following components.
-Binks Mach 1 with 1.5 tip
-2 quart pressure pot
-2 stage compressor/80 gal. tank (plenty of air)
Right now I have the air from the compressor set at 45psi.
The pot pressure is 8psi.
Finish is a white pigmented waterborne lacquer( Fuhr)
I have had good results with waterborne in the past.
The problem I am having is that I am getting banding on the surfaces.
Some areas are the appropriate sheen and some are dull.
I spray a wet coat pass, then 50% overlap that with the next pass.
I might be using too much air, as the second pass seems to dry the material from the first pass too quickly.
I have been trying different pressures but still having this problem.
Temp in the shop is 60F.
Perhaps I need a retarder for the finish?
Any suggestions on how to set up the pressures and controls is greatly appreciated!
Thanks,
Tom
Replies
If you are trying lower pressures and that is not working, and I am assuming that the other settings are sensible you should try slowing down the drying rate of the finish.... if it is possible. I dont use the water based stuff so I don't know how it can be mixed.
One error I see a lot of people make is holding the gun too far away. If you get closer the finish will fall wetter and you will get less of the dry fall texture on the edges. The right distance varies an a lot of factors, but I would say less than 10" is a good place to start. Remember you will have to move faster as well.
Post your results to let us know if you are able to work it out.
Pardon my spelling,
Mike
Make sure that your next project is beyond your skill and requires tools you don't have. You won't regret it.
I don't think the problem is with the finish drying to fast. Its more of an application adjustment. Like Mike said, you may be spraying at a distance to far away. This would give the results you have seen. Also you may be spraying to little fluid and moving very slow trying to get a wet coat. This could be because the lacquer is to thick or you don't have enough pressure in the pot to push it out.
You want your gun adjusted and paint thinned just enough to give a fine mist and an even wet coat. Gun adjustments include different nozzles and fluid tips for different materials when using HVLP systems.
The best way to judge is to watch the line of finish as its going on. Position yourself at an angle where the light catches the surface and you can see just how wet a coat you are applying.
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Position yourself at an angle where the light catches the surface and you can see just how wet a coat you are applying.
This is really a key issue for beginning sprayers to understand. Catching a good reflection will tell you a lot about how things are going as you spray, and allow you to adjust your technique/gun settings on-the-fly to compensate.
I will usually spray out a test pattern on a piece of scrap, cardboard or something along those lines. A quick head-on blast will tell you the effective width of your fan and how evenly the material is applying. Laying down a quick pass or two will tell you how wet the material is going on and, to the more experienced eye, whether the viscosity is appropriate or needs to be adjusted.
Having really good lighting from such an angle that catching a reflection isn't too hard really is hugely important. It can easily be (and almost always is) the difference between a flawless finish and a bunch of runs or orange peel which will have to be fixed and then resprayed. It's the reason why automotive spray booths have banks of lights overhead, along the side walls and at 45 degree angles in the corners.
Edited 1/30/2007 12:09 pm ET by Kevin
Hi everyone,I have gotten the finishing under control.Some previous advice I had gotten from a local supplier was not good.
The pressure was too high and thus drying the previous pass too fast as I put down the next pass. That caused the banding.So I lowered the incoming air to 30psi and the pot pressure to 7psi.
I'm spraying at about 6 - 7 inches away.
Now I'm getting a nice consistent wet coat that flows out nicely.And thanks for the advice on the light. It is really important!
I will be building a spray room soon and will get some banks of florescent lights.Anyway, the waterborne takes a bit of time to adjust to, but I think it is well worth the effort. Very nice product, nice not having all the air pollution from the solvent based.TomYou Don't Know.
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Just a quick suggestion on lighting for your future spray room. A very effective way of getting that angled lighting that I've seen done is to build a reflective shroud using some type of shiny metal which you can then sorta aim in a rough way. I've seen this done with standard, normally hung florescent lights to very good effect in a paint shop. In that case the shiny metal shroud material had been rolled into a curve so that you got reflective light from a variety of angles which was really, really nice but not absolutely necessary in order for the concept to have been useful and effective.
Thanks for the tip Kevin, I have a couple of questions!Do you kind of point the florescents at the shiny curves?
Where do the lights and the reflective surfaces hang in the room?Tom
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Well... I don't have my own paint shop. I'm a hired gun. And the one that I remember having used this shroud method so effectively was well over 15 years ago. But as I recall...
The light was hung normally (chains from the ceiling) and it was a room light rather than a booth light. We had a spray booth on one end of the room which had it's own explosion-proof lighting. But that was all overhead lighting. So some brilliant mind decided to get more usage out of the room lighting to shed more light on what we were painting (flexible-louver shutters). The particular 8' light fixture chosen for this treatment was back behind where we sprayed, hanging parallel to the booth, and shone downwards as is normal. The shroud was basically a piece of.... maybe 4'x8' thin sheetmetal rolled and then mounted to the backside of the light fixture so that about 3/4 of the shroud was curving around the backside of the fixture... which served to reflect the light forwards into the spray area.
The basic idea is the same in principle as a "trouble light" (the kind that you clip onto the underside of your car's hood when you are working on the motor) which uses a bare lightbulb with an aluminum shroud to increase and focus the light in one direction. Same exact idea, different application.
Of course you wouldn't have to use a custom rolled piece of metal. A little creative bending ought to achieve comparable results. Something coming down at a 45 degree angle on the backside of the light should function more or less the same and cast the reflective light fowards into your spray area. Bigger is better, of course, since the bigger the reflective surface the more light will be reflected forwards. But there are practical limitations to how big a piece of even lightweight metal you can hang off of a light fixture and I'd imagine that at a certain distance from the actual light source you'd reach a point of diminishing returns anyway.
The other thing that you'll want to do which helps enormously is to paint your walls and ceiling a bright, crisp white because white reflects. Believe me, it can also make a huge difference!
Oops!Thought I was out of the woods on this but not quite.
Still had some crackling problems occuring.
Called the rep and he suggested that it generally occurs from too thick a coat. Also suggested thinning about 5%.So, did those and now getting good results with no crackling and better flow out.After all this you can bet I'm keeping notes on all this!
Don't want to figure this all out from scratch the next time.TomYou Don't Know.
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Another follow up.
Still continued to have inconsistent results.
So finally drove down the the distributors store and met with
their expert.
He had me set up the pot and gun differently.
Incoming air about 50psi, or about 45 with gun trigger depressed.
Worked out the pot pressure to 6.5 psi.
And he recommended I spray 3 to 4 inches away!
Much closer than the 6 or so I was doing.We also added some retarder to the paint.
Now I am truly getting consistent repeatable results.One other thing, he gave me a gun cleaner solution, said
not to use soap and water. The soap can have all kinds of things in
that can mess up the paint chemistry.Should be building the spray room soon.TomYou Don't Know.
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That is an interesting set up. Almost sound like a detail gun. I bet if you added more retarder you could increase the distance/ fan spray. If I remember right you said you are using a water base finish... What is the product and what is the retarder? I haven't heard of retarders for water born varnish. Sounds like the guy knows his stuff.Pardon my spelling,
Mike
Make sure that your next project is beyond your skill and requires tools you don't have. You won't regret it.
Mike,The product is by Fuhr,Universal Acrylic Top Coat.
It is a waterborne lacquer.
The retarder is also Fuhr.I just looked at what we sprayed earlier today.
Looking good!TomYou Don't Know.
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