airless sprayer - paint

[andrew whicker]

Hi,

I painted a door today with a Graco cordless handheld FFLP (green tip) painter. I used 514 (.014") tip for this coat. The previous coat was also rough so I decided to use the top gun speed (10) and went slower and tried to get the gun closer to 12" to the surface. I don't paint a lot, so I'm still experimenting a bit.

The previous coat with similar results surface finish wise was with the same tip, moving faster and I think I was further away.

The other tips I have on hand hare a .010 and a .017.

What are your thoughts?


476207

[Tom M King]

You don't want to be farther away than 12". I'm closer than that almost always. Is the finish the same all over? One thing I see a lot of people do that I don't is fan the fan at the ends of a stroke. Keep it perpendicular to the surface always, use the trigger, and go past the edge a bit for start and stop of a stroke.

My first guess is you're keeping the fan too far away from the surface to get it to flow out good.

What paint?

I know nothing about that particular gun. Does it show pressure? "Gun speed" doesn't register with me for any meaning. Is it a variation in pressure? That should be the right tip.

[John TenEyck]

I've never used an airless but I've sprayed a lot of paint on cabinets and that looks too heavy by a lot. I'd turn the flow way down and make two passes, at right angles, if you aren't already doing so. Depending upon what finish you are using you also may benefit from adding some Extender so the finish has plenty of time to flow out. Practice on scrap to get it right.

John

[Tom M King]

Andrew, I was wondering if you made progress on this. If the gun is held too far away, as with any kind of spray gun, the finish becomes less atomized, and starts to form droplets. If you notice in my video, the amount of pressure controls the amount of fluid flow. A pressure higher than ideal pushes too much finish out, making it hard to control. Spraying with airless is really not that much different than spraying with any other type, other than you don't have to thin, so there is much less chance of sagging, even when you're applying it too thick.

edited to add: If you notice in my testing video, I like to wear a glove on my left hand. I can tell how thick it is good enough by dragging my finger through it if it seems questionable.

[Rich Engelhardt]

First off - go here and read everything:
https://www.graco.com/us/en/contractor/solutions/interior-finishing/paint.html

Even though a lot of the material will reference larger airless sprayers, the mechanics are actually similar. The larger pumps pick up material and feed it through small orifice at high pressure. The handheld units do the exact same thing.
A 413 size tip is the same for both. That number translates to a tip that has an 8" fan width at 12" from the surface (2 times the first number)(Graco tips are always rated at 12" from the surface) and a 13 thousandths size orifice that will determine the flow rate.

[Tom M King]

The orifice size determines the flow rate for a given pressure. You can fine tune the pressure to get the flow rate you want. The orifice size really determines the amount of atomization you get for a given finish using the normal range or airless pressure, but you still need to find the ideal pressure for your usage.

Even before gauges were available, you had to test to find the right pressure. Too low a pressure leaves thick lines on the edges of the fan. You had to keep increasing the pressure until it blew out those hard lines. Air Assisted Airless uses air pressure, not used with regular airless, to blow out those hard edges so you can get by with a lower pressure than without the air assist. AAA is not really needed these days since they came out with Fine Finish Low Pressure tips that can now be used with airless alone.

[Jason Roehl]

Andrew, I was a painting contractor for nearly 20 years. I have put tens of thousands of gallons of paint through airless sprayers. I almost never held the gun 12” from the surface—4-6” was far more common.

Pressure is determined by the material and the orifice. Increasing pressure beyond what fills the spray pattern only leads to bounce-back, overspray, wasted material, and a lot of paint in the air.

Many people make the mistake, particularly with acrylic/latex paints of trying to mist on a coat. That’s not how waterborne paints work—they typically need a thicker coat to be able to level properly before the solvents flash off. This also why you don’t want too much atomization or distance from the surface as too-small droplets will start to dry and either leave a pebbly surface, or not stick at all. The proper technique is keeping the gun perpendicular to the surface, an even speed, a sharp, full trigger pull, and a consistent pattern overlap. Don’t fan it around with your wrist. If you spray an 18” long test pattern on a piece of cardboard, you should have essentially a rectangle, not an hour-glass, and the pattern should look evenly filled, not splotchy, wet and shiny, not bumpy.