I've had some success (finally!) with my Fuji 4-stage HVLP setup. I'm
spraying latex paint, with the #4 orifice and needle. I thinned the
paint with water to get the viscosity per the manual. It took a lot more
water than I was expecting it to - as much as one part water to one part
paint. I also added Floetrol, albeit not as much as the directions on
the container. The final viscosity with water and Floetrol is in range
(20-30 seconds through the cup). It didn't take much fiddling with the
gun to get a nice, even pattern. I applied several light coats, and
waited about 30 minutes between them. The results are great! Except ...
I have sprayed a semigloss and a gloss latex. In both cases, the finish
is flat. I read the Floetrol will cause that. Is that the only reason?
Does thinning do that as well? How can I get a semigloss or gloss finish
when spraying latex paint?
Get ready for some screams from fellow participants on this group.
Here's the real skinny, anyway.
You don't need Floetrol when you spray.
Given the quality of today's latex paints, I wouldn't and don't screw
with it when spraying.
Let the screaming and teeth gnashing begin.
Floetrol is a plasticizer, and it affects the viscosity and the
density of the paint. The reason you are losing your sheen is because
the solids in the paint are separating from the resins due to you
modifying (goofing up) the paint formula by introducing materials that
alter the chemical composition of the latex paint.
This separation isn't apparent when you brush or roll latex material,
which is the original intended application of Floetrol. Using a brush/
roller, the paint is not blown apart into droplets then reassembled on
the surface of your project when you brush or roll. Also, you amplify
this problem of desegregation of the solids when you further thin the
materials you intend to spray.
Next, you are not getting enough material on your project if it is dry
enough to recoat in 20 minutes. Even if it feels dry, even if it
passes the thumbprint test, don't believe it. If it is dry to the
touch and and passes the thumbprint, then it is wayyyy overthinned.
Follow the manufacturer's MSDS or application instructions when
applying, as it is their product. There are plenty of coatings you
can create your own installation techniques to use as you see fit, but
latex paint isn't one of them. The cheap paint isn't worth the bucket
it comes in, and the good stuff is a wonder of modern science.
Last, I am thinking that you are setting up your gun wrong to spray
latex. I have the same exact Fuji setup. I don't thin latex nearly
that much when spraying. Try turning down the flow to the aircap, and
turn up the pressure as a first adjustment. Latex will not spray
like a solvent based finish (which is almost atomized), and
essentially, you are throwing droplets with your HVLP gun when you
This means you have to get enough latex material on the project to
maintain a wet surface long enough to lay out properly (20 minutes
won't do it). Remember, latex does not resolvate, so to get the
proper end finish "off the gun", you have to let the latex dry and
contract to form the surface tension that will pull out the anomalies
in the finish left by application such as stripes left by inconsistent
application, brush strokes or roller marks.
Drop the Floetrol when spraying. Check this out:
All you need to know about Floetrol is there.
Toss out your Ford cup and get out your measuring devices. That thing
is supposed to be a guideline anyway, not the final word on material
viscosity for application. Measure by volume, not by hit and miss to
get you material to go through the cup. To start, thin the paint by
about 10%, stir well, then shoot some test pieces with different gun
adjustments. Allow your test pieces to dry so you can see what the
layout will actually be. On a primed surface (even though it will
appear dry) this could take 2 hours. Keep good notes about settings
on the gun as well as how much you thinned, and how much material you
applied in a pass.
As a sidebar, I took a file and marked each knob on the gun with a
notch at 12 o'clock when completely closed. So when I shoot a certain
kind of paint, thinned a certain way, I can pull out my notes and open
the knobs accurately by registering the turns as I adjust.
Back to the problem. Didn't get it done? Try it thinned to 15%.
Keep going until you get the proper gun setup and viscosity, but not
thinning more than 30%. 30% isn't good at all, but if you go more you
are in serious danger of ruining your paint. If I had to thin that
much, I would change brands.
I have thinned as much as 30% for one of those damn gel paints, but it
wasn't a good material to spray (I think it was a Ralph Lauren
paint). IF your gun is set up properly, and you have to thin more
than about 25 - 30%, you need to change paints.
I have shot semi gloss/full gloss enamels out of my Fuji in Sherwyn
Williams brand, Coronado, Behr, and Glidden. Glidden was the dirtiest
paint, but I think it may have been a bad batch. I am always
suspicious of it though as it is the only remaining clay base latex
paint out there, the rest being XXoxide, depending on the
manufacturer. The Glidden paints are a joy to shoot out of my
Remember that no two paints will spray exactly the same, and the devil
is in the details. It's that last 10% of figuring out exactly how to
apply a finish that makes the 90% of what people see worth looking at
on the finished product. Buy yourself a gallon of the brand of paint
you are working with and take it out back and experiment with it. It
will really pay off in the end.
Damn, Robert ... we're almost there. Just a few more posts like this and my
book on spraying will be finished and all I'll have to do is to actually buy
a spray rig for appearances.
Keep up the good work! :)
Yeah... what's up with that? It is hard for me to believe I can
convince myself that I need another gun... yet it happens.
And they are so damn affordable now it is almost like catching a
disease. We can all buy a good pressure guns (even a CAS HVLPs) for
less than we used to buy the needles or packing kits for the old high
I am keeping the count under 10, though. Even if I have to sell/give
On Tue, 13 May 2008 00:15:58 -0700 (PDT), firstname.lastname@example.org wrote:
Wow, Robert - thanks!
OK, that part is easy. No more Floetrol.
Is there a tradeoff here? Thin the material enough to spray, apply it
thick enough on each pass and give the applied coating time to properly
cure, vs. having too much material on a vertical surface and have
I was using Behr and Benjamin Moore paints, which I _think_ are well
regarded. I don't recall seeing any thinning or spraying instructions on
the cans, but I'll don my glasses and check again. And I'll see if they
have anything posted on their websites.
I am not reducing the pressure at all. The air control valve isn't even
in my setup at the moment. The aircap adjustment is maybe a turn or turn
and a half back from full stop. Any more and I get blobs instead of
spray. In general, and as a starting point, would I need to open that up
more or less for a less thinned paint?
Thanks again for taking the time to write all this down, Robert. Much
appreciated. I'm off to the shop to play ....
Thanks, Leon. You know, one of the things I found interesting about
finishing was the fact that it is MUCH more than it appears to be.
And now with all the new technical/industrial finishes out there it
can be quite interesting.
Sometimes I laugh at myself because I feel like Dr. Frankenstein when
mixing and spraying, but in the end, all the work is usually worth it.
replying to nailshooter41, Climber5ap wrote:
I'm new to spraying, I have recently gotten a Vaper gun from northern tool with
a 2.3mm nozzle. I am trying to shoot a glidden paint and primer semi gloss for
trim work and interior doors. I have been thinning it about 20% with windshield
washer fluid and the gun is spraying it well. I have 2 issues, the first and
most annoying is that when it dries, it looks like a satin at best. The second
issue is that the finish is rough, but I have a feeling that is more technique
than anything else. I would love some input as to why I can't seem to get a
good semi gloss finish!
Robert is sure to pipe in (and I always call him for advice when I have
less than satisfactory results with my own paint efforts), but one of
the things I've learned to first try is using "gloss" for all the base
coats; and your preferred sheen (in your case, semi-gloss) only on the
Easy to see if it solves your particular problem.
I use the paint as a colorant in water based lacquer, with the lacquer
selected by sheen.
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