Do I need to thin water based polyurethane when spraying ?

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Forum topic by Carloz posted 10-24-2016 04:19 PM 1987 views 0 times favorited 4 replies Add to Favorites Watch
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1147 posts in 767 days

10-24-2016 04:19 PM

Do two stage HVLP such as Fuji Semi Pro 2 or Earlex 6002 ( 5 and 4.5 psi) have enough pressure to spray General Finishes High Performance Water Based Top Coat ( What a name !!! ) without thinning ? The manufactures are vague on this.

4 replies so far

View Fred Hargis's profile

Fred Hargis

5143 posts in 2669 days

#1 posted 10-24-2016 04:57 PM

I’ve sprayed it with my Fuji 4 stage and a 1.8mm needle set though I think I did thin it 10% with water. Be careful to not add more water than the manufacturer says, it can screw up the coalescing process.

-- Our village hasn't lost it's idiot, he was elected to congress.

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1147 posts in 767 days

#2 posted 10-24-2016 05:16 PM

Just found it: The guy from General Finishes. sprays it with a much less powerful Earlex 5500 without thinning.

View AlaskaGuy's profile


4644 posts in 2485 days

#3 posted 10-24-2016 05:42 PM

It would really be nice if finish manufacture woulds would put the viscosity time on the label.

Example: 25 seconds in a #4 ford cup. It would make it so much easier to pick a spray tip size and pressure.

-- Alaskan's for Global warming!

View rwyoung's profile


409 posts in 3648 days

#4 posted 10-24-2016 07:22 PM

Viscosity is given on the technical data sheet (but not the label).

Given as 35-45 seconds with a Ford #4 at 77F. Quick survey of Fuji manual suggests they want 15-18 seconds for polyurethenes and the 2mm N/N set. However this could be the wrong manual.

All such numbers extracted from manuals and data sheets are merely starting points for setting up the system(s). Test prior to spraying a project. Big sheet of cardboard makes a good target, reasonably simulates spraying a wooden surface.

-- Don't sweat the petty things and don't pet the sweaty things.

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