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-   -   paint gun problems (http://www.hotrodders.com/forum/paint-gun-problems-213663.html)

inkfreak1976 01-30-2012 11:52 PM

paint gun problems
 
I am useing a finish line primer gun, and im trying to spray epoxy primer.
I shot the door jambs first and the paint came out almost like spater.
and just doing the engine compartment jambs door jambs and trunk lid and jamb took 1000 cc of product for two coats. the first coat came out spatered. I started off with 10 psi with a large spray patern, the second coat went on fine but i turned down to 8 psi and it sprayed nice enough to fix the first coat. now im getting ready to shoot the rest of the car and need to know how to not have the same problem. I did not reduce the epoxy/cat. mix for the jambs.
should i, I felt that that much product was insane for that little area, the guy at the paint store said that i should be able to get a sealer coat for bare metal and a sealer coat for the urathane out of the same gallon? should i reduce, increase psi ????? im useing ppg omni epoxy with the proper 70 deg cat.
any help would help me out a ton.

stich626 01-31-2012 01:26 AM

whats the tech sheet for that product say?
you did get those with the product?

jcclark 01-31-2012 04:55 AM

Are you measuring 10 PSI at the tip?
All guns take way more than that at the gun inlet to get 10 psi
at the tip like they advertise.
(My Astro takes 45 psi at the gun inlet to make 10 at the tip.)
I hope you're not measuring 10 at the gun inlet.
Read your gun specs to know what it needs at the inlet.
they vary a lot.

MLA55 01-31-2012 06:21 AM

Sounds to me like you may have to big of tip,what size are you using?

skip99 01-31-2012 08:41 AM

i use the same gun and omni epoxy, use a 1.4 tip and about 20-30 lbs at the gun inlet, dial down the pattern to about 8 - 10 inches, reduce with up to 10 % acetone...and spray fairly slow to keep it wet, ..
mp 170 only uses one catalyst mp175. so not sure what the 70 degree is...
also for small areas, i"ll set a pattern at about 4 " tall and just dial the needle to allow a good wet spray , 4-6 inches from surface..

tech sheet is here..
https://buyat.ppg.com/refinishProductCatalog/

jcclark 01-31-2012 10:45 AM

Useing epoxy as a sealer coat means reducing it as much as 50%.
(with urethane reducer)
That's what most do, it eliminates the build and goes on real slick that way.
No advantage having it thicker. ;)

dinger 01-31-2012 11:51 AM

Have you thoroughly cleaned your gun? Taking EVERYTHING apart for cleaning? There may be some build-up inside the needle seat.

inkfreak1976 01-31-2012 12:48 PM

after reading some of your great responses, I beleive i have done many things wrong. imagian that. I am new to hvlp guns and also to this epoxy primer.
I was going by the air inlet gauge at 10 psi mistake one, and for some reason i never even thought of cleaning a new gun mistake #2, I mixed the epoxy/cat. as marked in the spec sheet and did set the air inlet to recomended spec at the inlet. the first coat i didnt wait a full fifteen min. after mixing, the second coat i did and it sprayed much better. but with all this stuff that went on in the first coat how in all gods name did i get it to lay down perfectly on the 2nd coat and dry smooth as glass.
now im getting ready to do this primeing in the next few days, after what i discribed how should i go about fixing the problems, more air is the obveus thing but should i reduce by ten percent. just the jambs took a lot of primer and ive got to get at least a metal seal and a sealer for color coat.
thanks

inkfreak1976 01-31-2012 12:50 PM

Quote:

Originally Posted by skip99
i use the same gun and omni epoxy, use a 1.4 tip and about 20-30 lbs at the gun inlet, dial down the pattern to about 8 - 10 inches, reduce with up to 10 % acetone...and spray fairly slow to keep it wet, ..
mp 170 only uses one catalyst mp175. so not sure what the 70 degree is...
also for small areas, i"ll set a pattern at about 4 " tall and just dial the needle to allow a good wet spray , 4-6 inches from surface..

tech sheet is here..
https://buyat.ppg.com/refinishProductCatalog/

its a 1.8 tip, its what the kit came with for primer applications.

matts37chev 01-31-2012 01:10 PM

Quote:

Originally Posted by MLA55
Sounds to me like you may have to big of tip,what size are you using?

Quote:

Originally Posted by inkfreak1976
its a 1.8 tip, its what the kit came with for primer applications.

the tech sheet in that link lists the tip size as 1.3 -1.6

mitmaks 01-31-2012 02:29 PM

Quote:

Originally Posted by inkfreak1976
its a 1.8 tip, its what the kit came with for primer applications.

1.8 is way too big for a epoxy sealer. It's designed for high build primers. Epoxy would be fine with 1.4 1.5 tip.

MLA55 01-31-2012 03:41 PM

That big tip is also your using too much material problem!

dinger 01-31-2012 04:27 PM

I was looking at my neighbors HLVP gun today, a H.F. sprayer, it actually works well. I did notice though that there is an air pressure adjustment at the inlet, so using a gauge before the inlet, unless the air adjustment is wide open, is useless. Just something to ponder on, he had some problems getting his adjusted until I pointed that out to him.

jcclark 01-31-2012 05:15 PM

Thats exactly right, most painters set the gun inlet adjustment
to wide open.
Also: The pressure measured at the gun useing a gage
is measured with the gun spraying wide open (trigger
completely pulled)
And unless you have oversized fittings and air hose, you need to
run high pressure to the gun's gage to compensate for the CFM losses
due to the std fittings, like 70 psi., then regulate down.
HVLP's take a lot of CFM, that's important for it to spray its best. :thumbup:


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