Gravitex undercoating suggestions

hun911 · 03-17-2018, 05:02 PM

I'm starting to undercoat my car with U-POL Gravitex Black. I have 12 Bottles. I hope it's enough!

But i have a question. I've practiced a bit with the gun and i found that around 45psi and 15cm distance gives the right texture.
My problem is that when i spray the surface, everything looks really fine. But when it startst to dry it starts to get a matte finish and looks like the material starts loosing it's texture and flattens out. What did i do wrong? The problem is that i didn't see the original underseal texture on my '69 car, so i'm just guessing based on photos here in the forum. Maybe somebody can post a closeup of an undercoating made with Gravitex.

My second question is that should i spray two layers? It looks to me, that if i spray the second layer an hour after the first, then the texture is more durable and doen't levels.

Third question: Is Gravitex good for every undersealing needs on the car? Bottom, Wheel Wells, Fenders, Trunk, Engine bay? And what about the gas tak? I know that Gravitex is good for the tank, but should i spray with a different texture?

Any opinions?

962porsche · 03-18-2018, 09:51 AM

gravitex is a low gloss finish . if you want some gloss add in some enamel paint up to 10% this will give it more gloss .
most people use the old type of chip guard guns . personally i hate them not any good for anything any more.
if this is the type of gun your using then i can't help with setting as that type of gun has none .
as for the amount of coats i will do two to 3 medium coats. but again i use a totally different type of gun that you can control the texture and pressure along with the fan pattern.
look up the lizard skin gun jegs sells them for about 80 dollars this is kind of the same gun i have.
i'm not sure if there are the same make i own but they look the same.

hun911 · 02:25 PM

Thank you for your answer. I've purcahsed the original U-Pol gun suggested for Gravitex. I think this is the same as all the other cheaper schutz guns. I've planned to repaint the matte finish with some 2k satin black paint or satin clear lacquer. I didn't know that i can mix the undercoating with paint. Can you maybe upload a photo of an undercoating you did with Gravitex? It would really help me to figure out what is the correct texture.

hun911 · 04:03 PM

I have this gun. Becuase it's not adjustable, so i think that's not what you use.

My car is a '69E. The front bonnet is still original and has the original sprayed sound insulation. Did the car have the same texture on the undercoating? Or is it different?

962porsche · 03-19-2018, 05:44 AM

this is the gun i use for chip guard .

962porsche · 03-19-2018, 05:53 AM

the gun you posted i use for getting sem rust shield down between two panels once they are welded together. we made up a few different plastic hose wands with little holes around the ends and the very end of the hose wands we plug to make the sem come out the little holes.
the wands slip over the end of the guns tip and hose clamp on.
the 1st one i made i didn't make the holes big enough and the sem blew out the breather vent.
it works real good to cover things like the inner rocks 360 degrees so your getting good rust protection on the inner part of panels.

Bob Kontak · Bob Kontak's Garage

Quote:

Originally Posted by hun911

I have this gun. Becuase it's not adjustable, so i think that's not what you use.

I use this gun and it lays down a pretty nice pebble finish using Gravitex. 60 PSI or so. I did my inner fenders, both the tub side and the fenders themselves, and painted over. I was happy.

Mind you, I also fill the jugs with Cosmoline or Fluid Film and blast the frames and rockers on old F250's.

It's as basic as you can get.

hun911 · 03-19-2018, 03:07 PM

Ok, but can i use it on the underside of the car also? Can you post a picture of the wheel wells shoot with gravitex in pebble finish? I really want to see how it has to look like.

Bob Kontak · Bob Kontak's Garage

Quote:

Originally Posted by hun911

Ok, but can i use it on the underside of the car also? Can you post a picture of the wheel wells shoot with gravitex in pebble finish? I really want to see how it has to look like.

I don't have pics close enough.

You may be assuming that I know how the Germans did it 35 years ago. I don't

Just use my post as a data point. You have way too much Gravitex also.

Here is a decent vid that gives you a hint of what I experienced. 962 can step in anytime and counter what I say. He is the Boss and I say that with massive respect.

This guy I think uses a little too much pressure.

https://www.youtube.com/watch?v=arYFt3AuYvI

hun911 · 04:29 PM

I waited for 962porsche's answer and arrived shortly with many useful info's. But maybe he missed that i asked him to post some pictures of a car made with gravitex (my post was too long, so it was easy to miss the question). And i have a new qurestion also: How long should i wait to spray the second coat on? My first coat leveles out as it dries. Only the second couat will have a good texture.

Bob Kontak · Bob Kontak's Garage

Quote:

Originally Posted by hun911

I waited for 962porsche's answer and arrived shortly with many useful info's. But maybe he missed that i asked him to post some pictures of a car made with gravitex (my post was too long, so it was easy to miss the question). And i have a new qurestion also: How long should i wait to spray the second coat on? My first coat leveles out as it dries. Only the second couat will have a good texture.

Get it 8" away at 60 psi.

There should not be a second coat required.

Are you cutting it with color?

Bob Kontak · Bob Kontak's Garage

[QUOTE=hun911;9967587 How long should i wait to spray the second coat on? [/QUOTE]

If you can attain a pebble finish on the second coat wait a half hour between.

Have a cig, if you smoke, text the kids and drink a beer.

Then get back to it.

962porsche · 03-20-2018, 04:52 AM

Quote:

Originally Posted by hun911

I waited for 962porsche's answer and arrived shortly with many useful info's. But maybe he missed that i asked him to post some pictures of a car made with gravitex (my post was too long, so it was easy to miss the question). And i have a new qurestion also: How long should i wait to spray the second coat on? My first coat leveles out as it dries. Only the second couat will have a good texture.

I DIDN'T KNOW THE YOU WERE ASKING ME .
because i'm semi retired and only work a few hours a day at my shop i have no job in the works right now with or getting chip guard.
the bugeye sprite i'm restoring now will be getting chip guard but not for a few week untill i do it .

962porsche · 03-20-2018, 04:55 AM

Quote:

Originally Posted by Bob Kontak

Get it 8" away at 60 psi.

There should not be a second coat required.

Are you cutting it with color?

on some jobs yes on others no it depends on the job and color. the sprite i'm doing now will not get more then one coat of chip guard untinted black but on a car like a porsche the chip guard is tinted to match the OE colors so they get two coats to match the proper texture and mil builds.

Bob Kontak · Bob Kontak's Garage

Quote:

Originally Posted by 962porsche

but on a car like a porsche the chip guard is tinted to match the OE colors so they get two coats to match the proper texture and mil builds.

Thanks for this input to help the OP.

Off topic but on the lighter side, most of the pickups I spray with cosmoline, fluid film or oil I don't have to remove the plastic plugs in the inner rockers because that panel is already rusted away. I have straight access to what's remaining.

hun911 · 03-20-2018, 11:42 AM

962porsche, i know you didn't know that i'm asking you. But i hoped that you answer!

I need to have black undercoating on my '69. So it's better to tint the balck Gravitex with 10% glossy enamel paint than spraying it with 2k black paint?

962porsche · 03-20-2018, 03:45 PM

if you paint over the chip guard your just adding a lay of product that can chip .
if you do not want a flat gloss and more of a medium gloss add the black enamel to the chip guard . this way there is nothing over it to ever chip . if your looking for a full gloss you would have to paint over the chip guard . but IMO full gloss just looks wrong in so many ways.

hun911 · 03-20-2018, 04:06 PM

Quote:

Originally Posted by 962porsche

if you paint over the chip guard your just adding a lay of product that can chip .
if you do not want a flat gloss and more of a medium gloss add the black enamel to the chip guard . this way there is nothing over it to ever chip . if your looking for a full gloss you would have to paint over the chip guard . but IMO full gloss just looks wrong in so many ways.

And what about a semi gloss overpaint? I think about it, because this way the undercoating is washable. But from '69 they also painted it in the factory, because the undercoating was beige. Or am i wrong? Or the painting was only from '70?

962porsche · 03-20-2018, 06:14 PM

they did not paint it like you would think it was just over spray . other then the rockers they were painted over the chip guard but what got onto the wheel houses and the little bit on the underside of the chassis should be just over spray.

Iciclehead · 03-21-2018, 06:46 AM

Quote:

Originally Posted by 962porsche

they did not paint it like you would think it was just over spray . other then the rockers they were painted over the chip guard but what got onto the wheel houses and the little bit on the underside of the chassis should be just over spray.

Having just blasted and primered my '89 chassis, what 962 said is pretty well correct (as usual). I had the blaster get rid of all the colour on my car (it was blue and will be orange) and the blasting they had to do on the underside looked like overspray or at most it looked like the painter just did a few swipes with the spray gun in the general direction of areas like the torsion tube, fender wells etc. Probably just using up the paint in the gun as in those days I have photo's showing that most of this stuff was being done by people....no robots.

Dennis