Setting pressure for spraying Gravitex - fast reply appreciated!

[n1tr0_9luteloop]

Im in the process of painting the underside of a car. I have hand painted Jotun 87 epoxy primer and then added seam sealer. Now im attempting to spray Gravitex over the top.

I am a total newbie to painting. I got a schutz gun with the Gravitex. From reading the bottle i need about 50 psi at the gun. I have a regulator in the compressor and an inline one at the gun. When i pull the trigger the pressure drops to about 30 psi and stays there. Playing with either regulator i can reduce the flow pressure to about 20 psi.

My question is when they say i need 50 psi, is that before or after i pull the trigger?

Before i pull the trigger the compressor is at about 100 psi, when trigger opened its about 30psi?

 

[WorkshopChris]

Normally figures quoted are at the gun full flow. Just adjust till you get the finish you require. Temperature ( liquid viscosity) can make just as much difference as air pressure.

Ps. Welcome to the forum.

 

[n1tr0_9luteloop]

Thanks. Just been reading maybe i need a smaller diameter hose? Im off to go experiment and actually see how it comes out!

 

[Swift&Bold]

Slightly off topic but has anybody applied Gravitex by brush?
The data sheet says it can be but does anybody have first hand experience?

 

[WorkshopChris]

Not with a brush but have used a small 4" emulsion roller to give a textured finish to flat steel panels.

 

[richie00boy]

Thanks. Just been reading maybe i need a smaller diameter hose? Im off to go experiment and actually see how it comes out!

You need a bigger hose if you are dropping too much pressure. Pressure values are always with trigger open.

 

[optima21]

Slightly off topic but has anybody applied Gravitex by brush?
The data sheet says it can be but does anybody have first hand experience?

I've painted the underneath of my car with a brush with gravitex. I put a couple of coats on over the top of a couple of coats on bilt hamber Elextrox primer. after 3 years some rust patches appeared, I was disappoiinted with the results, so on my other car I use jotun 87 applied by brush (without the gravitex) and it seems to give better results (after 3 years). both cars were taken back to bare metal before being painted underneath and both live outside (not garaged)

this is after the Gravitex was applied

 

[Swift&Bold]

I'm doing Jotun on mine at the moment but want to finish with Gravitex, not sure whether to brush stipple or roller it?
Spray isn't an option as I'm on my back and just don't have the room under there.

 

[marlinspike]

I have sprayed our wheel arches with Gravitex today. 24l Aldi compressor. Fast Mover underbody gun. I think the psi was 70 ish.

Afterwards, I sprayed a bit in a tub and stippled it on with a brush to get the bits right up to the edge where the masking tape was. It's quite thin so I would think you could paint or roller it on, though I would imagine you would use quite a bit more than when spraying it on.

 

[optima21]

if you stipple it with a brush the brushes become disposable, I ended up using Kingorigin paint brushes from Home Bargains (if you have a shop near you). their 1" wide paintbrushes are £0.29 each and their 2" wide paintbrushes are £0.49 each. they are cheap enough to be disposable and don't leave hairs behind either