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First time shooing a HVLP gun and paint came out splotchy.

16K views 10 replies 4 participants last post by  deadbodyman  
#1 · (Edited)
To extrapolate a bit: I am using a 1.5 tip on a hvlp shooting primer-surfacer. I mixed the primer exactly the way it directions said to do. It was 65degrees out and I mixed 4 part pimer/ 1 part hardener 10% cutting agent. It was the first time using the gun (it's a cambell hausfeild) and was shooting a board with the pressure regulator on the compressor at 50psi and then dialed in the gun with a regulator on the end at 10PSI ( the gun says on the tip max 10 psi). I then shot the paint but it came out in big drops, not a fine mist. I figured there was not enough cutting agent so I put another 10% cutting agent in and it came out a bit better but still splotchy. (then shot with both a regulator on the base of the gun and with the regulator off the gun and the regulator on the compressor at 10psi.)

Is the problem the tip or is the primer not cut enough? I've read you can cut it more and it just takes longer to dry.

The primer is brand Newstar ns-700. I had previously tried to look around to buy a 2.0 tip but could not find one? Is there a place to get just a tip for my gun?

One more thing. This was my first time using the gun and it was used. I tried taking it apart before I used it to clean it (although it looked imaculate) but could not get the part of the gun behind the tip to come off. It does unscrew --lefty-loosy-- right? I would imagine so.

Need all the help I can get. any replies appreciated. thanks

UPDATE


The general consensus is that I didn't have enough pressure to the gun. I'm going to try again today but a followup question for everyone.

I did go ahead and spray my trunk last night with the sprayer sprayin like it was. It was over bare metal and very thick instead of a light coat like everyone says to spray the first time. Should I sand it all back down or just sand smooth and spray again?
 
#6 ·
Sounds to me like you need more air pressure - what is the recommended inlet pressure of the gun?

The tip/ air cap may say 10PSI max (a HVLP standard), but you need to be giving the gun much more at the inlet to achieve that. Too low a pressure and the air cap simply won't be able to atomise properly, so it'll almost be throwing out lumps of primer, rather than a finely atomised spray.
 
#11 ·
Are you planning on painting the trunk or using a rubberized undercoating (one that gets hard)? If your painting I"d use a 2k sealer instead of primer ,it'll eliminate the need for more sanding ,some sealers adhere to the bare metal (sand through spots) very well.If you started with an epoxy sealer from the start there would be no sanding at all,and its thinner so there wouldn't be a problem getting it out of the gun.