Tip: SW P60G2 primer

[wirejock]

I learned a lesson working with Sherwin Williams P60G2 wash primer.
The mix for shooting a very thin layer on our airplane parts requires a 2 parts catalyst to 1 part primer mix. With all that catalyst, the mix sets up almost instantly. That's great for our parts.
Today I primed more parts than any session before so I mixed in batches of 12 oz of mixed primer. I do it so there is little waste when the day's project is done.
That worked great till I set the gun down to mix another batch and got pulled away for a few minutes. When I started spraying with the next batch, the spray came out like cotton candy.
I had to clean the gun out with lacquer thinner and wipe it off all the parts. It's not easy to get off.
So if your working with batches, clear the gun between by shooting a tablespoon of lacquer thinner through before starting the new batch. The gun worked much better this way.

 

[az_gila]

I learned a lesson working with Sherwin Williams P60G2 wash primer.
The mix for shooting a very thin layer on our airplane parts requires a 2 parts catalyst to 1 part primer mix. With all that catalyst, the mix sets up almost instantly. That's great for our parts.
Today I primed more parts than any session before so I mixed in batches of 12 oz of mixed primer. I do it so there is little waste when the day's project is done.
That worked great till I set the gun down to mix another batch and got pulled away for a few minutes. When I started spraying with the next batch, the spray came out like cotton candy.
I had to clean the gun out with lacquer thinner and wipe it off all the parts. It's not easy to get off.
So if your working with batches, clear the gun between by shooting a tablespoon of lacquer thinner through before starting the new batch. The gun worked much better this way.

Where does the 2:1 mix ratio com from?

S-W seems to only say to use 1.5:1 ratio....

http://www.paintdocs.com/webmsds/webPDF.jsp?SITEID=STORECAT&lang=E&doctype=PDS&prodno=P60G2

 

[wirejock]

mix ratio

Hey Gil.
It comes from a friend who shoots lots of the stuff.
1.5:1 would probably be ok but 2:1 is much easier to spray on smooth through the gun. Any thicker and it doesn't want to atomize completely.
I use 2:1 in my Develbiss HVLP at 27 psi. and it sprays a nice smooth finish.
You shoot till you just see a change in color on the piece. It looks way too thin but once dry gets much darker. I've weighed lots of parts before and after and get a consistent 1% weight gain.
If you shoot till it's dark, it's way too thick.

 

[az_gila]

Hey Gil.
It comes from a friend who shoots lots of the stuff.
1.5:1 would probably be ok but 2:1 is much easier to spray on smooth through the gun. Any thicker and it doesn't want to atomize completely.
I use 2:1 in my Develbiss HVLP at 27 psi. and it sprays a nice smooth finish.
You shoot till you just see a change in color on the piece. It looks way too thin but once dry gets much darker. I've weighed lots of parts before and after and get a consistent 1% weight gain.
If you shoot till it's dark, it's way too thick.

Maybe easier to spray... but -

"Industrial Wash Primer is a fast drying,
pretreatment type, 2 package, acid catalyzed
vinyl washcoat."

- you end up putting 33% more acid into the mix...

But sometimes the Tim Allen methods work better...

 

[wirejock]

Tim Allen

Maybe easier to spray... but -

"Industrial Wash Primer is a fast drying,
pretreatment type, 2 package, acid catalyzed
vinyl washcoat."

- you end up putting 33% more acid into the mix...

But sometimes the Tim Allen methods work better...

Hey maybe that's the answer. Mix it 1.5:1 and spray it at 100 psi!
Guess I better hook that V8 to my compressor.

Seriously though I see your a Tech Advisor. I read a bunch of threads and the consensus seems to be 2:1. One from a paint shop actually recommended 3:1.
If I'm doing something wrong, please tell me before I get too much farther down the path.

 

[az_gila]

Hey maybe that's the answer. Mix it 1.5:1 and spray it at 100 psi!
Guess I better hook that V8 to my compressor.

Seriously though I see your a Tech Advisor. I read a bunch of threads and the consensus seems to be 2:1. One from a paint shop actually recommended 3:1.
If I'm doing something wrong, please tell me before I get too much farther down the path.

Just going by the manufacturers data sheet.

This is usually the best source of data. It just seems to me that adding more acid might not be the best idea.

The fact that it can set up/thicken too fast with more catalyst is a hint the mixture is not correct.

I'm not an expert painter, but perhaps a larger nozzle on the gun might help?