Spraying High Fill Primer

[AmadeusCharger500]

Had some trouble with it. I have done this before and had good results but this is puzzling me. I mixed the paint for medium build.
It comes out as expected for the first minute and then turns to a very runny mess.
I tried mixing longer and using less thinnner, same thing.
Gun has a 1.6 tip.

Any suggestions?

[69fourspd]

Did you drain the compressor and do you have water filters on the gun/line?  Maybe you could try increasing your air flow.  If you are using an HVLP gun, bring the psi to around 40 and decrease your fluid out the tip. 

[Silver R/T]

theres too many factors to this,
first of all 1.6 is bit too small for high build primers, perfectly you want to go with 1.8 tip
did you stir it in a pot for a while, making sure thinner/primer mix together well
you fan adjusted too narrow
your air pressure needs adjustments

[AmadeusCharger500]

I tried widening the fan.
Air was 40 psi at the gun.
It is HVLP.
I did drain the tank and have 2 water filters.

I will try a bigger tip.

Just not sure why it starts out great then turns to sloppy mess.

[Silver R/T]

perhaps you're going/spraying too slow, also your distance needs to be 6 inches or more. Closer youre to surface faster you need to go and vice versa.

[Drop Top]

Sounds to me like the temp is not right for your reducer. In other words its to cold. You may need to change to a faster drying reducer.

[tan top]

Sounds to me like the temp is not right for your reducer. In other words its to cold. You may need to change to a faster drying reducer.

 
                  also try holding the further away when priming with a  slower hardener  & move a little faster  in colder temperatures / be careful though.. check masking .... as doing this will create more oversprey ,

[jordyjim]

did you get it sorted? you say it starts out great then turns bad? are you losing pressure at the gun? some times i bump the pressure up when applying a heavy primer,but dont pull the trigger right back it lets less through so atomises well,you dont get a wide fan though but its ok,and yes use a faster thinner with primers ,doesnt matter how dry it looks cos you sand primer down anyway, does this make sense to you?..jim

[hemi-hampton]

I special ordered a 2.0 tip for my primer gun since 1.6 is what they commonly stock. Sounds like you just need to stir the primer better. If to runny mix thicker. LEON.

[MichaelRW]

Get the tech sheet from your primer supplier and that will tell you exactly what to do. Tip size, temps for which reducer, HVLP spray pressure, etc.

[AmadeusCharger500]

I tried it again making sure I mixed well. Now the temp is 70 as opposed to the 40ish it was then. I would agree this is a temp problem plus some other variables.

Thanks so much!

When I was having trouble, I had only been mixing about 1/2 cup of paint. This recent time I mixed 1 cup and I noticed even though things went much better, it still got runny near the end of that amount. This leads me to think I also had a mixture problem.

[65post]

Sounds like the temp. in your garage is too cold and maybe your loading it on a little to heavy.You should not put the first coat on too heavy. First coat should be semi - wet. Then  let it FLASH - OFF for at least 10 min.@ 70 degrees.( very important ) On the 2nd coat you should be able to lay down a nice wet coat without any trouble.And NEVER shoot primer or paint when you have HIGH humidity in or outside of the shop.