Sprayer Not Atomizing Properly

[Ken Krawford]

I’m finishing an outdoor wooden bench using a Fuji Mighty Mite 4 HVLP sprayer and a 1.8 N/N set. Yesterday I sprayed a coat of water based Kilz primer thinned about 15% and everything went as planned. This morning I lightly sanded it and started spraying my finish coat with Sherwin Williams Duration acrylic latex also thinned about 15%. No matter how I adjusted the gun the paint was splattering for lack of a better term. The only spraying recommendation on the can was for using an airless setup with a 1.3 - 1.9 NN.
I’m guessing that I still need to thin the product more but wondered if there's something else that I overlooked.
Thanks for any help you can offer.

[Jim Becker]

I'm using an HPLV conversion gun with the PPS system and for thicker paints like the Duration (which I just sprayed a few months ago on the big door of my shop as well as the 16' garage door on our home, I had to kick the pressure up substantially higher to get proper atomization for application. Like from the normal 45 PSI into the gun to nearly 60 PSI. That may be more difficult with a turbine. Airless is king for thick waterborne paints like the Duration or Emerald for good reasons.

[jack duren]

I’d thin it some more.

[Jim Becker]

I’d thin it some more.

At 15%, it's already at or beyond the recommended thinning for waterborne finish. Water is only the carrier, so when you add too much, you start to get a paint coating that's not distributed well, doesn't crosslink/cure as well and doesn't look good. Tract house builders come to mind around this particular technique.

[jack duren]

I stopped going by directions years ago. Reason I left cabinets and went into furniture…lol

[Jim Becker]

Lots of folks eschew RTFabulousM

[John TenEyck]

Unless you measure the viscosity you are flying blind. Get a #4 Ford cup and measure the viscosity of the stuff you thinned. I'm pretty sure you'll need to get the viscosity down to something below 100 seconds to spray it with your gun.

John

[Ken Krawford]

Thanks everyone for your comments & suggestions. John, I have a Ford cup sitting above my laundry sink where I clean my guin. Great idea!

[Jason Roehl]

At 15%, it's already at or beyond the recommended thinning for waterborne finish. Water is only the carrier, so when you add too much, you start to get a paint coating that's not distributed well, doesn't crosslink/cure as well and doesn't look good. Tract house builders come to mind around this particular technique.

I second this as a former professional painter. Over-thinning an exterior waterborne product will pretty much destroy its designed performance. It’s truly best to not thin them at all. I used a lot of Duration over the years, and it was definitely intended to be applied in a couple thick coats to achieve proper protection, durability, and look. That’s not going to happen very easily with any non-airless sprayer. Not to mention, with exterior paints going on porous substrates, they need to be back-brushed or back-rolled after spraying, especially the first coat.

[Tom M King]

It’s so easy with airless and no thinning.

[jack duren]

I’ve worked with a lot of professional painters who will tell you to thin if it won’t spray..

Different strokes for different folks..

There is no such thing as cant, just won’t..

[Jim Becker]

The bottom line, Jack, is that it's best when you don't need to thin; acceptable to thin up to what the manufacturer states is the limit; and risky to thin beyond that. Folks who want/need to spray thicker coatings a lot are best served investing in the right equipment to do that if what they have can't do it unthinned and is marginal with acceptable thinning. But one can certainly try thinning further, but it's best not to do that on the real project until it can be confirmed that the results are acceptable to the maker.

[jack duren]

Sorry Jim, but sometimes you have to put the manual down and get to work,

I remember when everyone said you couldn’t spray polyurethane either…lol

[John TenEyck]

Why not just use a product that will spray with your gun? SW's Emeral Urethane Trim Enamel sprays great for me at about 6 psi cup pressure when thinned 10%.

Or you could go old school and use a brush.

John

[jack duren]

I know most if not all commercial jobs in the KC have to be brushed if pre sprayed before it arrives..