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-   -   Removing Airless Sprayer Paint Runs (http://www.diychatroom.com/f4/removing-airless-sprayer-paint-runs-119440/)

Twister 10-07-2011 10:23 AM

Removing Airless Sprayer Paint Runs
 
Guys -

I used an airless sprayer to topcoat some ceiling crown with Sherwin-Williams Pro-Classic acrylic latex (white, semi-gloss). 1st coat looked mirror smooth. I was so proud of myself I could have cried. Sprayed the 2nd coat on last night and I got a few runs. I was so #@!!*!! I could have cried! :mad::mad::mad:

The paint spec sheet says it dries to the touch in one hour and can be recoated in 4 hours. It's been on for 10 hours.

Question: how long do you guys recommend I wait before trying to sand out the runs?

Question: any other techniques to remove them other than using a high grit sandpaper?

Question: are 2nd coats more prone to get runs? (EVERYTHING stayed the same; paint, sprayer, gun, tip, pressure, etc).

I must have got the gun too close or moved it just a little too slow in those areas......

(BTW, this stuff was painted on a latex primer. Different wood trim than mentioned in an earlier post).

I've been trying to master the airless sprayer for a while now and it will say that it's not as easy as it looks to get that smooth, even arm movement down. Lot to think about: gun perpendicular? distance? movement rate? rig pressure? trigger squeeze and release technique to eliminate spattering? I am a perfectionist and I want to get it just right.

Brushjockey 10-07-2011 04:29 PM

We try to warn people that spraying isn't easy-
Yes the second coat might run easier because it is going on a harder, more sealed surface than the primer.
Most guys have a good brush handy- and if anything starts to run they brush it out while it's still wet. Better to have a few brush strokes than a drip.
One thing about the new waterbornes- they don't sand out as nice as good old oil. They tend to clump off, and don't feather well.
Hopefully you don't have lots of it. Sand the best you can, then might require spackle ( Bordens wood filler is good for this) to get a nice feathered edge.
Then the whole 9- sand, prime , 2 coats. Might want to do most of it by hand- spot prime.

jschaben 10-07-2011 06:31 PM

I use a thin blade putty knife sharpened to a chisel edge. Cut off the run and touch up with a brush. Not quite perfect but you almost have to know it's there to see it. :whistling2:

jsheridan 10-07-2011 09:24 PM

Twister, there's no crying in painting!:laughing:

How many is a few? Is it the real meaning of few, as in a small number, like three, or is it more like the number of beers you really had when asked the question? :laughing:

I've used a long, breakaway knife, flex it slightly cupped, and slice it parallel to the surface and found that does a nice job, with oil anyway. A little rubbing with a rag and denatured alcohol after knifing it may knock down any remaining glitch.

ltd 10-07-2011 09:26 PM

pro classic will sag on second coat:(. even for the pros if your not careful:yes: .big runs can be scraped with single edge razor then i like to wet sand with 3m or gator paper. this paper holds up to water:wink:

Twister 10-08-2011 12:30 AM

jsheridan -

A "few" meaning I had 3 of 4 corners in my master bedroom closet that had runs. I used 3M 220 to sand the heavy stuff off and then finished it up with 600. Got it danged smooth. Switched from a Graco 312 FFT to a Graco 212 FFT for the next attempt. Spit waaay less on the ends of each pass testing it on some painters paper I hung in the closet.

OK, humble-pie time.....

so I just finished spraying the next coat on (with the 212 FFT tip and, much to my surprise I've got runs AGAIN!!!! What the frick?!?!?!?!? Again, only in the corners. I spent almost 3 hours making a cool looking spray shield for the corners so I could eliminate the runs. No dice. I obviously am putting out too much paint in the corners. How do you professional painters avoid this? The technique of squeezing the trigger once and keeping the gun moving through the corners seems VERY prone for putting out excessive paint in corners but I may be forced to try that technique.

LTD, so, why is Sherwin-Williams Pro-Classic acrylic latex so susceptible to runs on 2nd coats and what do I do to prevent it?????????

jsheridan 10-08-2011 06:39 AM

Easy Twister. If you get yourself worked up, you'll make it worse. I've done a lot of difficult work over the years and frustration can easily compound your problem. But, I do understand it. I've done very little spraying over the years, so I personally don't have a specific tip (no pun), unless you count rattle cans, which I use regularly. There are some common app techniques with painting. Never start or stop with the applicator focused directly at the work. When you spray with cans, the trigger is pushed before the fan hits the object and released after the object is passed. Brushing and rolling are similar. When you end a brush stroke you're gradually lifting the brush away from the surface, fade. Similar to an airplane lifting off and touching down. The quantity of material that hits the surface is a function of speed and distance. If you did the lengths fine then obviously your speed is slowing in the corners, you might try to back it off a bit and round the corner more. These are just thoughts I would be thinking if doing your project. If your walls aren't painted, practice making the turns in the corner on the drywall. And think, what did you do in the one corner, which is fine, but didn't do in the others? Hope this helps, stay calm, good luck.
Joe

Twister 10-08-2011 08:47 AM

Quote:

Originally Posted by jsheridan (Post 744245)
Easy Twister. If you get yourself worked up, you'll make it worse. I've done a lot of difficult work over the years and frustration can easily compound your problem. But, I do understand it. I've done very little spraying over the years, so I personally don't have a specific tip (no pun), unless you count rattle cans, which I use regularly. There are some common app techniques with painting. Never start or stop with the applicator focused directly at the work. When you spray with cans, the trigger is pushed before the fan hits the object and released after the object is passed. Brushing and rolling are similar. When you end a brush stroke you're gradually lifting the brush away from the surface, fade. Similar to an airplane lifting off and touching down. The quantity of material that hits the surface is a function of speed and distance. If you did the lengths fine then obviously your speed is slowing in the corners, you might try to back it off a bit and round the corner more. These are just thoughts I would be thinking if doing your project. If your walls aren't painted, practice making the turns in the corner on the drywall. And think, what did you do in the one corner, which is fine, but didn't do in the others? Hope this helps, stay calm, good luck.
Joe

Joe -

Thx for the encouragement and specific advice. For the technique of squeezing the trigger once and moving the gun through all the corners, what confuses me is that the gun is supposed to be perpendicular/90 degrees to your surface at all times (according to my sprayer rig manual). But then you have a 90 degree corner so when you finish one wall, with the trigger still squeezed, you need to quickly twist/rotate the gun to the next wall and keep moving. Rotate it too fast and you get too little coverage as you begin the next wall, rotate it too slow and you get big time runs/sags as you begin the next wall. It's that twist/rotation in the corner that makes me nervous. I've seen it done on YouTube clips, but again, seeing it and doing it correctly are two different things. Do you just have to think of the corners as rounded and not squared off and accept that the gun won't be perpendicular to your work surface for an instant?

Gotta go sand it down again :( and spray later today. The 212 FFT sprayed on some test paper with virtually zero spattering, which was awesome, but I think I'm going to try it with less pressure, hold the gun a little further back. Will also tape up some paper in a corner and practice on that.

Again, my hat's off to the pros, because it ain't as easy as it looks.

Brushjockey 10-08-2011 09:04 AM

Corners and multiple angles that hit the same spot are THE reason I don't recommend a DIY to take on cabs- particularly for the first project.
It is a combo of all elements- mix. speed angle distance, tip etc. Release trigger just before the corner and the follow through will hit it lightly.
This is something that watching someone who knows how is invaluable. It is hard to explain.
I do do little spraying, that when i do (enameling) I use my HVLP- goes slower- but more forgiving. Need to stay in practice with an airless.


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