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x711 11-11-2005 09:14 PM

HVLP Spray guns and paint viscosity:
Hi all,

I am using a 1.4mm HVLP gun with Valspar single stage urethane paint. Now to my question.

How does one know if the actual paint needs to be reduced or not prior
to painting. Is there a acid test that can be performed during the mixing
stage i.e mixing the activator with the paint before its put in the gun. My idea
is to try get the paint in the best viscosity window prior to putting it in the cup.

Thus save some time on testing various ratios of reducer prior to painting.

Any ideas or suggestions are most welcome.

Thanks for your insight..


Bee4Me 11-11-2005 09:37 PM

Spray some and SEE.
Your asking the 64 million dollar question dude.
ALL gun's,people,paint spray different.
Set up the gun as recomended by IT'S manual,Mix the paint as recomended by IT"S tech sheet,PAINT a junk panel and ADJUST from there.
AFTER you've PAINTED something,Come back and we'll tell you what to do if it's not working out.
I'm NOT trying to be a smart *** but NOBODY can tell you EXACTLY what to do with a bunch of UNKNOWN'S.

x711 11-11-2005 10:41 PM

HVLP Spray guns and paint viscosity:
Ok bee4me, I hear you. But certain guns are designed to
spray material at a specific viscosity, putting my question another
way how do I check the viscosity of the sprayable material, prior
to spraying said material.

I know the real test is putting it in the cup and shooting but surely
there is a more scientific approach to this. For example how do Auto manufacturers keep the viscosity of their paint consistant on a production
line etc. If the viscosity changes then the end result will change so they
have to be doing something to keep the paint in a certain window.

There has got to be a fool proof method to measure this ..I am real curious
about this, any takers ?

Thanks X

milo 11-11-2005 10:45 PM

Theres whats called a Zahn Mix cup


x711 11-11-2005 11:32 PM

Thanks Milo, thats what I am looking for.

So basically its a flow test over time.

It might be over kill for the job I am doing, but paint aint cheap
so its good to run a few tests first.

Thanks for the heads up !


milo 11-12-2005 12:28 AM

Of course we need to read whatever directions that are on the can and get as many different opinions etc.. but different guns act different depending...So a old school method was to touch your stir stick to a nearby horizontal surface and learn its dribble time so to speak..

In other words fling it against the wall and see how long it'll stick...

After a while you'll be able to feel it through the stir stick as you mix yet the gravity test is always there to fall back on..

Heres a nearby thread that may help too..

MARTINSR 11-12-2005 08:52 AM

You know what cracks me up about this subject, it is right in the tech sheet, you mix according to the ratio recommended by the manufacturer, PERIOD and it WILL work.

I have always done it this way with all 2K products. Back in the lacquer days, sure, I used a viscosity cup every day, with a stop watch.

Since I have used 2k products, I used a stir stick with the ratios onit and then moved up to E-Z mix cups. VERY, VERY seldom ever leaving the manufacturers recommendations.

Then as a paint rep doing demos in shops, I mixed the product EXACTLY as recommended by the manufacturer I was working for every single time.

I never even have thought about what kind of gun, I watched one of the most well known guys from a major gun manufacturer (now with a different manufacturer) spray a fender with clear out of a 1.0 Sharpe Platinum mixing it exactly as recommended and it looked like glass.

That 1.4 HVLP is one of the recommended guns in the tech sheets (I assume). They don't show different mixing ratios for different guns do they? No, they show a list of guns to use and the one mixing ratio. Notice all the dry and cure times are different with different "temp" reducers, THAT is what changes things, not by changing the mixing ratio.

The mixing ratio and a proper mixing cup is all you need.



“Basics of Basics” Mixing cups
By Brian Martin

Your mixing cup with have a number of sections. These sections will be the different ratios and then there is usually one or two with just a "ruler" with equal parts and then also parts in ounces.

In the sections of ratios you will have a few columns. Find the section that is 4:2:1. In that section there look at the first column and you will see numbers going up 1,2,3,4 and so on. The first column is your "4" where you will add your paint, clear of primer. The second column is the "2" in your 4:2:1 ratio and that is where you will add your reducer. The last column is your "1" and that is where you will add your hardener.

Ok, look that last column and find the number that will give you the amount of mixed paint, primer or clear that you want.

Let's say it is a half a pint and you are mixing in a pint mixing cup. We will say that the middle of the cup is at the number 5 in the hardener column. That is where you finished mix is going to be.

So, you will pour your paint, primer, or clear up the number 5 in the first column (this is in the 4:2:1 ratio section remember). So, you have the paint,primer, clear up to that number 5 in the first column.

You now add the reducer up the number 5 that is in the second column. That number 5 is about one half more than the first column you will notice. It is two "parts" more than the first column at the number 5. You are now with the paint,primer, and clear, along with the reducer up to the number 5 in the second column.

Now you add your hardener up the number 5 in the last of the three columns in your 4:2:1 ratio section and that is it.

Mix it up and you are ready to go.

Remember "parts" are simply equal parts. Be it table spoons or 55 gallon drums, just equal parts.

You could, if you wished, mix 4 tablespoons to 2 tablesspoons to 1 tablespoon.

Or mix 4 55 gallon drums to 2 55 gallon drums to 1 55 gallon drum.

They both would do the exact same thing. Just the same as the 4:2:1 in your mixing cup.

Bee4Me 11-12-2005 10:09 AM


but surely
there is a more scientific approach to this.

x711 I'm really not trying to make light of you or what your asking but,
Ain't nothing scientific about sprayin' paint.
Even with EVERYTHING set up and mixed and adjusted correctly you have a BIG uncontrolled variable.
That, and Karma or the Ide's or whatever form of "luck" you believe.
Some day's you can do NO wrong,Some day's are best just not even opening a can of paint.
Painting IS trial & error as YOU have to APPLY the product. The MORE you apply,the BETTER you get (supposed to work that way,Right?)
Paint costs money and I understand but nobody EVER said painting was CHEAP.
If your trying to save some $$$ by disecting everything to the Nth degree,good luck my friend cause it just does NOT work that way.Ther are no "sure fire recipe's".Conditions change and so should you.Adaptation is the ART of painting.We HAVE to do things that are NOT in the rule book.
You have to paint to learn.PERIOD.

x711 11-12-2005 12:18 PM

HVLP Spray guns and paint viscosity:
Hey guys, thanks for the advice. I agree that for the most part the tech
sheet will get you in the window with respect to mixing ratios so this is a good starting point, then comes the tweek factor.

Where I am coming from is this and I guess if I had painted as long as some
of you I would have more experience, hence I try to dig as deep as I can and then go paint.

One of my tech sheets for primer has a mix ratio for a hvlp gun that has a range of 1.6mm to 2.0 mm. Talking with the manufacturer they told me that
I would have difficult spraying the material at a ratio of 4:1:0 with a 1.8mm
gun and it would be best to reduce the primer, which was fine.

For regular build primer they show on the tech sheet that a ratio of 4:1:1
is ok, but in my setup I found that a 4:1:1.5 ratio was better. The primer
went on very smooth.

So where I am coming from is this, since the liquid was slightly more reduced
that meant it had a thinner viscosity and the gun was able to atomize the fluid better.

So hence my post about the viscosity of the paint. I think this is something
that any newbe painter should be aware of right out the gate.
"It can reduce hair pulling" :)

Thanks for your insight. X

Timer 11-12-2005 03:40 PM

DuPont, BASF, Akzo Nobel, S&W(upper end clears and such), and Some Other Smaller Paint Companies such as Rubber Seal normally have a viscosity listing in their TECH SHEETS.
Info about the Viscosity Cups.

ULTRA 7000® Super Glamour Clearcoat CC639
"• Viscosity (sprayable) #2 Zahn 16-18 sec" :welcome:

MARTINSR 11-12-2005 10:13 PM

LOL, you are very right, but if you simply mix it according to the mix ratio it is going to be within that with out needing to measure it.


chadsbodyshop49119 11-12-2005 11:49 PM

I think there is way too much effort to get the same results, mix it like it says and if it is to thick for you to spray run outta the booth and ad a little reducer.. and go back to they say... no exact science here.

Bee4Me 11-13-2005 03:03 PM

SEE, You gotta PAINT to learn. :thumbup:

All part of the curve x711.
I'm playing Devil's advocate here with you to prove some important points to new painter's so don't get bent on me,You've played along and I appreciate you indulging me.

HVLP is confusing enough in it's own right.
MOST tech sheet's state 8-10 psi at the cap spraying pressure.
Show me a newbie painter that understands THAT and I'll buy you a gal of HOK base.
I use an Iwata HVLP that recommends 16-18 psi at the gun to give the recommended 8-10 at the cap. Also,they state to spray 4-5" off the PANEL.
Talk about "different". That's SO far from the norm for painting I could not believe it. IT WORK'S cause I tried it "their" way after not having much luck "my" way.Sure I can fool around with the gun and get it to spray my way but it defeats the whole design of the gun.

Same applies to paint product's.You can fool around and make them work "your" way or LEARN the PROPER way to use them.

Point being, If you follow the Manuf. recommendations,your almost home.

Sometime's. :evil:

This is the BIG reason WHY this web board is one of the BEST.
REAL people who PAINT and KNOW what works,what doesn't,what to use.

x711 11-13-2005 03:35 PM

HVLP Spray guns and paint viscosity:
Hey bee4me, I aint getting bent on you, I appreciate you
and others taking your time to help a newbe painter out.

Its really very interesting stuff, You make some very good points.

I did some more testing with the guns I have last night, but I am not getting
the results I taught I should. I used a Sharpe Finex 1.4mm gun and also
a Sharpe finex 1.0mm gun to lay some single stage valspar Omega 2k paint.

Anyway I mixed the paint with the activator per the Tech sheet from valspar
and ran some tests with both the 1.0, 1.4mm gun.

Keeping about 8" from the object I was spraying I noticed the following.

The 1.0mm gun did pretty good but when the paint flashed off and dried
it had peel in it. I did 3 passes, letting the paint flash between passes.

The 1.4mm gun put more paint down, but after flashing off and drying
the object had more peel. Prior to shooting I did a spray test and adjusted both guns as best I could.

In both cases I noticed the following. The droplet size seemed to me to
be a little large and non uniform even after upping the air pressure a couple of pounds in the hope of atomizing the paint better. Its almost like the guns
were not able to break down the SS paint properly.

After upping the pressure The droplet size did decrease but less material
was getting delivered so I increased the flow of fluid to compensate. After
increasing the flow, I had a bigger spray pattern but still the same deal. iT
looked like there was a atomization problem to me. So I am thinking that
the guns are not really suitable for the type of paint I have.

I did some research last night and will put a call into devilbiss tomorrow
as I am interested in there new Plus GFG-670 gun as perhaps a better
avenue to go in laying this SS paint.

I would welcome any comments that anyone has on the GFG-670 or on
what they feel might be causing my atomization problem with the sharpe
guns. The devilbiss costs alot more than the sharpe so its a diferent class
of gun.

Thanks for your help.


Bee4Me 11-14-2005 11:12 AM

You answered your own question but don't realize it. ;)

You stated earlier about having to reduce the primer cause it would not lay out right due to too small of a tip in the gun.........

SAME problem with the paint.

Single stage is thick compaired to a regular base paint so you either need a larger tip or MORE air with the 1.4 OR, Reduce the paint about 10% or so to get it to flow out better. I'd try more air as HVLP's are notorious for being "on the verge" of spraying properly,Compliant thing and all you know, So bumping the air up 10 psi will help. This set with the trigger FULLY pulled of course.
I have a Finex touch up which recomends 28# at the gun and I usually run 30# AND reduce the SS the 10% I spoke of. IF I'm spraying clear,I'll go to 35 with a medium solids (Nason Select 497) with NO reduction as I WANT the build.
IF you have a 1.6 for either full sized gun's,try that as well for the SS.

Trial & Error man,Trial & Error.
Rocket science at it's BEST!!

I prefer the S.W.A.G. method myself.

Scientific Wild *** Guess. :evil:

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