2k Poly mess (dry spray?)

[Romain]

Hi everyone,

I will try to keep things simple
I am trying to finish a table top.
plywood with oak veneer, aniline waterbase dye (dried 3 days).
After loads of crater/fish eye/brushmarks issues trying to apply with paintbrush, I have now switched to paint gun hoping I would have better chances.
i have a michelin gun HVPL with I believe a 1.5 mm pin. i spray in a spray booth with good temp / extraction conditions.
I am using 2k poly (formulated for spraying) with 5% solvent
Last try was with 4 bar pressure, close to fully open fan pattern with no obvious pattern default.
I tried spraygun in the past and was successful on a smaller piece sprayed vertically.
I am now spraying a 2 x 1 meter pannel horizontally.
I can't seem to progress fast enough on the piece to get a "wet coat". Trying to do so, before I get to the middle of the pannel I have some visible dried up particles on the board (dry spray? overspray?) looks like large grain sandpaper
The final result therefore is coarse and dull...
I don't get it. I am nearly defeated by this piece. it's the 7th tim I have to level it trying not to damage the dye. I am exausted. And it MUST leave the shop monday.

My only theory is that I have too much air pressure (gun recommends 3 to 5 bar using 4). i do nottice a lot of overspray.
Any help welcome (

[mature one]

yep if you get misty overspray reduce the pressure you are in my opinion getting more air than paint with the pressure used.

[mark david]

I have done a fair bit of spray finishing myself, I use pre-cat nitrocellulose.and gsn get reasonable results and have sprayed a couple of 2 metre dining tables outdoors !.
-I now get all my furniture professionally sprayed by a local guy.
If you are using 4 bar pressur that's probably about double what you need ! I spray around 25-30 psi too much pressure and air volume results in almost no finish staying on the piece and creates a vapour cloud. You need a scrap piece of board to test on to get the gun set up correctly, I would not normally spray we ith the fan at full width, I you spray on a scrap board place vertically you should get an even band of finish vertically.
I am far from an expert so you may get better advice from a more experienced finisher.

[soundman]

HVLP gun at 60PSI does not sound right

sounds like you are splurting it every where due to high pressure and lack pf pattern control ..... thus your wet coat ain't wet and you have excessive overspray.

cheers