noob with gun question??

[1800xn]

hey all
new to the forum here, ive been reading and using search function as well....lots of good stuff here..any ways this is prolly a stupid question but hey im just startin out so go easy..lol i stripped down my front motorcycle fender and sanded it with some 220 grit for preping for primer..i mixed up my epoxy and waited thee induction time and practiced on some paper getting my setting for the gun. i couldnot get it to lay down smooth..are you suppopsed to use the little plastic filters in the gun when shooting primers??? i played with air and material adjustments and didnt seem to affect the out come of it.oh and im usin a 1.8 tip with air any where from 10 to 25 psi at the cap with trigger pulled.

thanks

 

[Wydir]

well for primer your going to sand it anyway so it don't really matter if its smooth or not. but I would not use a filter in my primer gun , But I would filter the primer before I put it in the cup.

 

[1800xn]

well for primer your going to sand it anyway so it don't really matter if its smooth or not. but I would not use a filter in my primer gun , But I would filter the primer before I put it in the cup.

ok yup i did filter it in a strainer before putting it in a cup. also another question??? i have a little bondo to put on as well so i know ill have to sand off some of the epoxy in the damaged area thats needs repaired for the bondo to go on, but i i just shot epoxy with out sealing it..so do i have to seal before coming on with the surfacer or just seal at the end once every thing is straight??

 

[Kong]

I too filter my paint as I pour it into the cup, that's the only filter I use for anything.

I'd be interested to know what gun you're using, but its not the most important thing in the world. You are going way overboard on that air adjustment. And by the way, assuming you have an HVLP gun that pressure is at the handle, not at the cap. Typically the pressure at the cap is 10 pounds but the pressure going into the gun will be something around 15~20. Your gun's manufacturer should have a recommendation for the handle pressure. You can go above it a little bit for better atomization, but just a couple of pounds is usually enough. For instance I believe Iwata recommends 18 pounds in for my LPH-300, but I usually set it at more like 20~22.

The other thing is that you can reduce epoxy primers just a bit using Acetone. I reduce epoxy 10% when I use it as a sealer before paint. That smooths it out a good bit. That said its really a moot point. When its time to get down to painting, when all the prep is done and you are shooting your actual final sealer coat you have just put yourself on the clock until the job is done. If you honor the manufacturer's recommendations for recoat windows you'll basically be shooting wet on wet from sealer to clear coat. In that case all the paint sort of melts together in a sense with each coat chemically bonded to the coats below and above it the only thing you really have to worry about is laying down that last coat of clear as slick as a baby's butt. And if not there is always the 2000p and the Makita.

 

[Wydir]

yes that is correct you cannot put bondo over primer has to be on bare metal only. and what do you mean by sealer? in a normal body filler repair I would sand to metal feather the edge of the paint a few inches from the damaged area the smear the filler then block it out apply your epoxy primer starting in the middle and each coat I would over lap and go closer to the featheredge but not going over the edge till the 3rd coat. then sand (prep for base) then I would blend the basecoat then clear the whole panel.

I guess I dont know what your working on so in your case it maybe different


example of the primer coats below hope its not confusing.

------------------ 3rd coat
--------- 2nd coat
---- first coat

 

[1800xn]

ok thanks you guys for the info, well i am using a TCP brand hvlp gun prolly not the best but for a beginner just starting out ill move up when the time comes. i am working on a front fender on my motorcycle that i bought which had previous damage to it.i had to strip down the whole fender due to damage and the fact of it having striping under the clear, i just felt it would be easier to strip it all. for the gun i set my air pressure to 10lbs with the trigger pulled and adjusted up from there no matter what the pressure rating was it just had to rough of a finish (orange peel look) so thats why i was wondering if i should or shouldnt have used the filter at the cup for spraying primer..

 

[Kong]

Wydir,

Who told you that you couldn't put filler on top of epoxy primer? Not only can you put the filler on top of the initial sealer its actually a better way to apply it. The reason is that the epoxy sealer will bond better to the bare metal than the filler will and the filler will bond to the epoxy better than it will to bare metal. On top of that the epoxy is impermeable to water, but many fillers are not, so the chance of future corrosion below the repair is much less if you first apply your sealer to the bare metal and then put your filler on top of it. And finally, when its time to sand you will find that the filler feathers better into the sealer than it will into the bare metal.

1800xn,

That gun should work fine for you. I think you misunderstand how the airflow and pressures work in HVLP guns, what you are seeing on the little dial at the bottom of the handle of your gun is the air pressure going into it, not the residual pressure at the cap when the trigger is at full pull. There is a big difference between the two, a full order of magnitude in many cases. That said unless you have one of the measuring systems you never really know what the pressure is at the cap, so all you can do is experiment with the inlet pressure. Once you find your gun's sweet spot it gets easier.

Now, what you need to do to get better results. The first thing is this, the gun you are using is basically a primer gun, that's why it has that great whopping big 1.8mm cap. When I say primer I am not referring to your epoxy primer/sealer, I mean plain old every day muddy and thick sandable filling primer. To shoot a thinner paint like the epoxy you'd probably get better results, and certainly better atomization, if you were using something more like a 1.3~1.4mm cap. But what you've got will work, just choke it down. If you've got a test panel to play with try adjusting your trigger pull back.

 

[1800xn]

Who told you that you couldn't put filler on top of epoxy primer? Not only can you put the filler on top of the initial sealer its actually a better way to apply it. The reason is that the epoxy sealer will bond better to the bare metal than the filler will and the filler will bond to the epoxy better than it will to bare metal. On top of that the epoxy is impermeable to water, but many fillers are not, so the chance of future corrosion below the repair is much less if you first apply your sealer to the bare metal and then put your filler on top of it. And finally, when its time to sand you will find that the filler feathers better into the sealer than it will into the bare metal.

ok thank ya sir!! i thought i read some where that i had to strip back the epoxy on the damaged area a lill bit before applying the filler, but also my main question was is do i use the little filters in the gun at the cup when shooting primer thats why i was thinking i couldnt get it to lay down, but as said it prolly dont really matter right now at this stage since i will be sanding down...thanks for the help.

 

[Wydir]

like we said before there should not be a filter in the gun cup at all this is why the flow is diminished. just strain it into the cup

I use a 1.6 in my Sata 100B RP and it sprays primer like basecoat. so when you get your gun figured out it should work just fine, I also spray between 4-6 inches from panel @ 1 foot per second, but depends on how the gun sprays and how fast your moving.

I was always taught to not put filler over primer except for glaze but everybody has their way of doing things.

 

[1800xn]

WOW!!! you guys are great!, thank you all for sharing your knowledge and tips, i have tried posting on another forum only to get no help or replies..thank yall again!

 

[Wydir]

must have been a crappy forum