Well I have tried and tried to make it work with waterborne finishes. Frustration and dissatifaction with the final results has made me rethink my path.

I started spray finishing about 2 yrs ago with a fuji mm4 and target based coatings. I had success on a few projects but quickly learned that the fuji didn't lay down the product fast enough to be efficient and get professional results. The target coatings products were so inconsitant that I had to return a bunch of product and find a different manufacturer. I did some research and found the valspar zenith finishes. I also switched to a compressor fed pressure pot water based gun system by Asturo.

While the Valspar zenith sprayed out very nicely and sanded very well it didn't impart any warmth to the wood without adding an extra step of oil before topcoating with the water base. How much sense does that make? I also found the zenith very problematic when polishing.

I've started on with MLCampbell's solvent based cv and precats. I am borrowing a gun from a shop neighbor. Man what a difference! The wood is so much more alive.

Now I need a different system and I don't want to have to go thru the same process of getting a system and wanting/having to upgade later. The Kremlin airmix system looks to be the cream of the crop and something I'll wont have to upgrade for a long time unless I get bigger britches.

Also when comparing VOCs the solvent based finish don't actually have much more than the comparable waterborne.

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Eiji, is the airmix system just a variation on HVLP technology?

If so, how does it differ?

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John

The Kremlin Airmix is an AAA system that has proprietary tip technology. That enables the system to use a lower fluid pressure and much less air than other systems. It also boasts a 70-80% transfer efficiency. Much more efficient than the best hvlps with the speed of an airless. Uses only about 4cfm. The only downside I see is the heavy initial investment of about 2500-3000.

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This all gets so confusing. My new Graco Finish Pro claims 85%-95% transfer efficiency with its "standard" HVLP technology.

I'm still a newbie with it (as well as spraying) so I can't say much about the claims, but it seems to work very well so far. Best of all, I haven't ruined anything yet.

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John

John,
Graco's claim of 85-95% seems a lil inflated. My understanding is that the only system that achieves more than 90% are electrostatics. ICBW

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I believe that's correct -- I wonder if you can "powder coat" wood...

Is there any way to actually test it? Or is it just supposed to be noticeable in the results?

Graco Fine Finish Brochure

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John

I use the Binks piston pump system: http://www.binks.com/LinkClick.aspx?...w%3D&tabid=257

and their gravity feed HVLP guns.


Mirko

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"Perfection is achieved, not when there is nothing more to add, but when there is nothing left to take away."

I think I found the answer to my own question :



Paint Transfer Efficiency

Transfer efficiency refers to a ratio representing that portion of sprayed paint that does land on the target part. This number is widely used in calculations involving paint application economics. It is common for manufacturers to advertise transfer efficiency ratings for their applicators which do not correspond with the actual efficiency that is obtainable in your paint process. Because this is an important measure of efficiency, two practical methods for calculating the actual transfer efficiency of installed systems are shown below. These methods are for single component material applications.



TE by Weight

The most accurate method of calculating transfer efficiency is by weighing the part prior to painting and after painting. This should be done when the part is completely dry. This method will include in its result all film build variations, heavy edges, and wrap (paint on the reverse surface).


Paint Solids Weight on Part = Part Weight After Painting - Part Weight Before Painting


This yields the weight of the solids in the coating. Then, we must determine the weight of the paint solids dispensed from the applicator.


Paint Solids Weight Dispensed = Weight of Dispensed Paint X Paint % Solid Content by Weight


The weight of the dispensed paint can be calculated by multiplying the volume of the dispensed paint by its density.


Finally, the transfer efficiency by the weight method can be found.


Transfer Efficiency W = Paint Solids Weight on Part / Paint Solids Weight Dispensed



TE by Volume

If it is impractical to weigh parts, a very accurate method of calculating transfer efficiency is by measuring the volume of solids on the part after painting and comparing that to the volume of solids that was dispensed. This should also be done when the part is dry. This method will be as accurate as your model of film build distribution across the part.


Transfer Efficiency V = Paint Solids Volume on Part / Paint Solids Volume Dispensed


The volume of dispensed solids is easily determined in the manner similar to the method above.




.

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John

More :

SPRAY GUNS AND TRANSFER EFFICIENCY
by Ron Joseph

"There is a general misconception in industry that HVLP or electrostatic spray guns automatically yield high transfer efficiencies. Because of the wording that has been used in many air pollution regulations, there is a general belief that HVLP and electrostatic spray guns yield transfer efficiencies in excess of 65%. This is incorrect! It is true that HVLP and electrostatic spray guns, when properly used, are more efficient than conventional air atomizing spray guns, but their improved efficiency has no relation whatever to the 65% value that is often quoted in regulations and vendor literature.

For example, if a properly operating conventional air atomizing spray gun used to apply coating to a set of small parts yields a transfer efficiency of say 5%, then an HVLP or electrostatic spray gun might produce a slightly higher efficiency, say 7 - 10%, but not much higher than that.

On the other hand, if all three spray guns are properly used to apply coating to a large surface, then all three devices can be expected to yield relatively high transfer efficiencies, perhaps even greater than the mystical 65%. The HVLP and electrostatic guns will probably yield slightly higher results than those for the conventional air atomizing spray done.

By far the most important parameters for maximizing transfer efficiency are in the hands of painting operators. An operator using a conventional air atomizing spray gun who has been properly trained and uses efficient painting techniques will be far more effective in improving transfer efficiency than an operator who uses an HVLP or electrostatic spray gun, but has not been trained in proper painting practices."


Actually, I've learned some new stuff today, I thank Eiji for starting this thread. That's why I like to hang out here.

Some of what I learned is purely academic for me, because I've already invested in a spray outfit, and I ain't gonna be changing it anytime soon, no matter what the latest technology is.

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John