Airless paint sprayer help: primer OK, but enamel has streaks/tails


  #1  
Old 01-03-07, 06:30 AM
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Airless paint sprayer help: primer OK, but enamel has streaks/tails

I have a Graco Magnum DX sprayer with the 515 tip (0.015"). I also added another 25' 1/4" hose section at the sprayer and coupled that to the 3/16" 25' hose that came with the sprayer. I am painting my trim and doors in my basement. The sprayer worked well for the latex primer (Sherwin Williams PrepRite Classic). I set the sprayer to about half pressure (middle of full and prime/clean).

I then flushed the sprayer with water and then paint thinner and switched to the enamel (Sherwin Williams ProClassic Interior Alkyd Satin Enamel). At half pressure there was considerable streaking/tails in the paint pattern (4 or 5 main streams of paint). At full pressure the streaking/tails were better but still not very good. I then tried a 411 tip (0.011") but the spray with that was worse than the 515 tip.

The enamel is considerably thinner than the latex so I thought the smaller tip was going to help but it did not. I have cleaned the gun filter and flushed the sprayer again.

Should I try using just the one 25' 1/4" hose or maybe just the 25' 3/16" hose?
Should I try a 0.017" tip even though the max tip for the DX is 0.015"?
Or is this sprayer just not going to work for the enamel?

Thank you!!
 
  #2  
Old 01-03-07, 06:46 AM
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Welcome to the diy forums

I'm not familiar with that particular pump but whenever you have streaks/tails in the spray pattern it is usually caused by insufficent pressure or worn tip.

How new are the pump and tips? Both need to be in better condition to properly spray oil base, latex is a little more forgiving.

When you switched to oil base are you sure you pumped all of the thinner out of the system? I usually pump a pint or so of paint back into the bucket before attaching the tip and spraying.
 
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Old 01-03-07, 07:25 AM
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The pump and tips are new. After the thinner I spray out some of the paint back into the bucket but probably not a whole pint.

The spray pattern gets better with more pressure. The paint can says 0.015" to 0.017" tip at 2000 psi. So I would think my pump at max pressure would be enough.

Another thing I do not understand is why is the pattern worse with the smaller 0.011" tip?

Thank you for the help!!
 
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Old 01-03-07, 09:53 AM
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Try running more paint thru the pump back into the bucket. Even though it is a small pump it should be capable of spraying enamel. If I remember correctly, 100' of spray line holds close to a quart of paint. While the paint pushes the thinner out of the system, all the thinner isn't completely gone when paint first appears.

If that doesn't solve it, you may want to go back to the SWP store and talk over your spray problems with them.
 
  #5  
Old 01-03-07, 10:33 AM
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Your hose may be the issue. If I understand your OP, you are running 1 section of 3/16 and 1 section of 1/4. Your hose is inadequate for maintaining pressure surges.

I would recommend you use 1 section 50' run 1/4" (minimum) and then a 3' 3/16" whip for flexibility.

Your hose is constricting the fluid flow, and decreasing pressure. This will contribute to tails and other symptoms you are exeriencing.

A larger diameter hose will help absorb the pressure flux of the pump (that most likely is running constantly to maintain pressure).

Good luck!
 
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Old 01-03-07, 11:02 AM
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I talked to the paint store and the painter who did the trim in the rest of my house and I concluded I need to try removing one of the hoses and there are also green graco FFT tips for finer paint that might help. Hopefully the hose is the problem and I won't have to buy a new tip.
 
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Old 01-03-07, 11:28 AM
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Actually, shorter hose may lead to more problems. 50' hose would be the minimum that I would consider acceptable. The paint in the line acts like a buffer for the pressure surge everytime the pump cycles. With only 25' hose, you are more likely to have problems with exessive spray/low spray.

But make sure it's at least 1/4" for the 50' run.

Good luck
 
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Old 01-03-07, 12:00 PM
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The pump does not run constantly at full pressure. It runs normally (every once in awhile after spraying). Does this mean I do not have a pressure/hose problem? The pump came with the 25' 3/16" hose so I was thinking to just try that but as always, I'm open to suggestions.
 
  #9  
Old 01-03-07, 01:26 PM
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The pump came with it because it lowers the cost of the pump. It has nothing to do with performance.

For latex applications, with backrolling it would be acceptable as you would be rolling away all the problems. As you are experiencing, this setup is NOT adequate for your application.

BTW "Pump not always running" is irrelevent. It will mitigate some of the problems, but every time the pump kicks over you are getting a BLAST of high pressure through the lines. Hence the need for longer, larger diameter hose.

50' of 1/4" hose is the MINIMUM that I personally would run on ANY airless rig. The fluid is under enourmous pressure and the paint in the line acts like a buffer to reduce the pressure shock at the gun. You may not feel the knock, but your finish will reflect it!

Plus, 3/16" is really only acceptable for 3' whips. It is more flexible than 1/4".

If you were doing this full time, I would even suggest thinking about 5/8" hose, but that runs about $100 per 50' run.

I can't even recall how many hundreds of pumps that I have sold. With your situation, I would recomennd:'

1. 50' 1/4" airless hose
2. 3' 3/16" whip (not necessary, but more comfortable)
3. Clean Gun Filter
4. .515 Graco FF tip (Fine Finish)

5. Pressure pump up to full, and back off about 1 1/2 turns.

Your pressure may be a bit over 2000 psi, but it will not FALL below 2000 PSI during application.

Good luck.
 
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Old 01-03-07, 01:27 PM
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Since the unit came with a smaller diameter spray line, I wouldn't think that would be the problem. I assume you had the smaller line at the end of the line. It is true that the bigger heavier duty pumps need a minimum of 50' of 1/4" line to operate properly. I don't know if this would be an issue with the smaller light duty pumps.

The pump will run as needed. A small pump like yours would probably run constantly under heavy duty spraying. Let us know what you find out.
 
  #11  
Old 01-03-07, 03:20 PM
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I stand by my post. Marksr check your PM.

Use 50' 1/4" hose. It will help.
 
  #12  
Old 01-03-07, 05:29 PM
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Soak the tips in thinner and scrub them clean. Take the tip holder off and make sure it's clean inside. Strain the paint and use a filter sock on the pickup. Also make sure that the pickup is well submerged in the paint. Forget the marks on the dial and run up the pressure just until the tails disappear and add just a touch more pressure.

I'd get rid of the extra 25' of hose and use just a 3' whip with a swivel on the gun end. There may be something to the long hose rationale but the little DX doesn't need it. I use mine to spray waterbase straight from the can all the time.

Jan
 
  #13  
Old 01-04-07, 06:46 AM
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I bought a Graco FF 312 tip (green) yesterday and it works much better. I still have to have the pressure maxed out but I am getting an acceptable spray pattern now. I didn't mess with the hoses yet but I'll let you guys know if I end up trying a different hose configuration.
 
 

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