DIY Fix Body Rust, Prime and Raptor Paint

gilee

Sprinter T1N Camper
This is totally new territory for me... Thank you.
I will look into that as well! THX!!
 

bored

Active member
Compressed air is measured in two ways..... pressure and volume.

Pressure is measured in PSI. Volume is measured by CFM....

Spray guns need the correct amount of air to run properly. Even a cheap gun needs those parameters. When I kick the air pressure up to say 37 (which is the most) its because I want to dust the paint on. It gives the car more of a satin finish. By increasing the air pressure the paint dries incredibly fast and can't settle which is fine for a multi-layer top coat that will be clear coated. You are shooting primer with this gun which needs to properly adhere to the surface or you are eliminating any purpose of primer and might as well use primer out of a spray can. You need to shoot the primer at 26 at the highest.

Compressor and Gun go hand and hand. If you had a Tekna Pro you would still get terrible results with a compressor that can't keep.
 

gilee

Sprinter T1N Camper
Compressed air is measured in two ways..... pressure and volume.

Pressure is measured in PSI. Volume is measured by CFM....

Spray guns need the correct amount of air to run properly. Even a cheap gun needs those parameters. When I kick the air pressure up to say 37 (which is the most) its because I want to dust the paint on. It gives the car more of a satin finish. By increasing the air pressure the paint dries incredibly fast and can't settle which is fine for a multi-layer top coat that will be clear coated. You are shooting primer with this gun which needs to properly adhere to the surface or you are eliminating any purpose of primer and might as well use primer out of a spray can. You need to shoot the primer at 26 at the highest.

Compressor and Gun go hand and hand. If you had a Tekna Pro you would still get terrible results with a compressor that can't keep.
Thank you.
So for example, if the HVLP gun is stated needing 4CFM, then as long as I buy a compressor that can supply 4cfm @ 45psi, then its be good?
since you said prime best at ~20PSI, CFM will be higher.

Am I missing anything else? The gallon wont be a big factor right? A 5+ gallon tank be good enough?
 

bored

Active member
No.

Tons of variables.... What nozzle and needle size are you using? Every gun is different? How thick is the paint? How cold or hot is it? and on and on.

Regardless you are way off on how much SCFM you will need.

The general rule is a minimum of 10 HP dual pump compressor tank size at least 50 gallons. Anything smaller and I have no idea what you will get but its primer so you can keep sanding till are you happy with the result.

My Tekna Pro settings depending on the nozzle

703540 (HVLP)
HV30 1.4 – 1.6 bar
20 – 24 psi
411 – 467 LPM
14.5 – 16.5 SCFM

703538
(High Efficiency)
TE10
1.4 – 2.4 bar
20 – 35 psi
212 – 311 LPM
7.5 – 11.0 SCFM

703539
(High Efficiency)
TE20
1.1 – 1.8 bar
16 – 26 psi
255 – 340 LPM
9 – 12 SCFM
 

bored

Active member
BTW...My recommendation is focus of removing all the rust. You can't paint over rust even minor rust on the body. You can't bondo over paint unless is newer OEM paint but your van is to old to bondo over the existing paint. You will need to bring it down to metal where ever there is rust and needs body work. After the bondo is sanded you can put a light coat of "spray can" primer to seal it because you don't want surface rust building while you get all the body work done.

Once that is done then you can decide on painting.
 

Zundfolge

1-2-4-5-3
Remember that you can always rent a good compressor for one day too - just remember that water separator, no telling what those before you have done, and drain the tank a couple of times before you use.

I would hesitate to use a pancake for this job. I didn't look too closely at your pic but it looked like a thin hose. Like stated you're looking for volume with an HVLP, so make sure you have something like a 1/2" hose (opposed to 1/4" that comes with many compressors like yours).

5-ish years ago I built and sprayed a whole room of built-in cabinetry. Used a cheap-ish HF gun with my nice makita compressor (6.5CFM @90PSI). Even that seemed undergunned for the job, and I had to let it catch up at times. When you've got paint loaded you don't want to have to wait for anything, especially when using a catalyst-type paint (like raptor is I think?). I'm by no means a painting pro, and there are some on here who are, so take my advice for what it's worth.

So I say that to say, make sure your equipment is up to the task first. I would pay more attention to that detail next time I spray something sizeable...
 

gilee

Sprinter T1N Camper
Thanks for all the input everyone.
I cannot throw money in like nothing, but if I am going to fix the rust spot, I want to do it right.
I will look into it more and weight on what options I can have based on my budget.
 

bored

Active member
Thanks for all the input everyone.
I cannot throw money in like nothing, but if I am going to fix the rust spot, I want to do it right.
I will look into it more and weight on what options I can have based on my budget.
Send photos of the rust and I can tell what should be done.

Also if other parts of your body is rusty then check carefully around the windshield. Most likely it need to come out to properly remove the rust. I had mine removed by a professional and it still cracked. Its nearly impossible to remove them without cracking especially if its still OEM windshield. So if it comes out figure into the budget a new windshield.
 

99sport

Active member
I took my entire roof down to bare metal and then put Monstaliner magnapoxy epoxy primer on with a roller (top coat was Monstaliner). You CAN wet sand epoxy primer if you want to smooth any issues, but it takes forever - the stuff is tough. I didn't need it to be perfect since it was the roof and I put bedliner on top. The whole point of epoxy is that it is waterproof, which other primers typically are not.

I also tested SPI epoxy primer. It was easier to get a smooth texture with a roller and also wet sands. Plus it's white. Magnapoxy is dark grey and I needed 6 coats of white Monstaliner to cover it.

I did a LOT of test samples on scrap sheet metal to prove I had worked out the proper technique and got results I was happy with before painting the van. Even so, its MUCH easier to do a couple square feet than a whole van. These products start setting up quickly when it is hot outside.
 

bored

Active member
I would not use epoxy primer on the sides of the van.

Of the two, epoxy is a higher-strength substance that prevents a surface from moving. Though epoxy is strong, it will crack on surfaces that frequently move. Urethane retains flexibility. Structures that contract or expand with seasons or temperatures are better suited for urethane.
You might get away with it on the doors and hood and for sure on the top because no one will see it but no way it doesn't eventually crack on the side with time and exposure to different climates. .
 

gilee

Sprinter T1N Camper
Something like this would be the minimum. Compressors build up water in the tank over time, and it can end up in the line. Liquid water going through the nozzle will cause spotting on the paint.

View attachment 176612
Just got my Husky Gravity HVLP Spray Gun spec is 4.3CFM @ 40psi) .
I will be trying it with my pancake compressor.
I also bought the Husky Air Filter/water.
20210406_174537.jpg
It say filter particles from air, and water.... Want to make sure it is the right one.
Thanks guys!
 

gilee

Sprinter T1N Camper
I just messing around with the HVLP gun and filter, and wonder if i can mount the filter horizontal to the gun? If not, i need an angle fitting to my spray gun, but what if I spray horizontal surface?
Screenshot_20210406-225811_Gallery.jpg
I also bought the regulator, so I can keep the pressure at a specific PSI at the gun.

I am abit concerned (hopefully I just dont know and worried too much)...
  • Can I just mount the filter on the compressor side? So it can stay stationary while I spray?
  • When I spray, especially near bottom of van and roof, if the filter is fixed to the gun, its impossible to stay horizontal... So maybe orientation doesn't matter?
Thanks all!!
 

marky

Member
I would recommend visiting your local autobody supply store and asking the sales guys what they would recommend. I have restored very rusted autobodies. If you can poke an awl or screw driver through the rusted area you should cut it out and weld in new sheet metal. But that is a lot more work and takes skill to weld sheet metal. For superficial rust clean off the rust as best as possible then use a converter to convert the remaining rust to inert iron phosphate. I would use products that professional auto body guys use.
 

tinman

Well-known member
I just messing around with the HVLP gun and filter, and wonder if i can mount the filter horizontal to the gun? If not, i need an angle fitting to my spray gun, but what if I spray horizontal surface?
View attachment 177422
I also bought the regulator, so I can keep the pressure at a specific PSI at the gun.

I am abit concerned (hopefully I just dont know and worried too much)...
  • Can I just mount the filter on the compressor side? So it can stay stationary while I spray?
  • When I spray, especially near bottom of van and roof, if the filter is fixed to the gun, its impossible to stay horizontal... So maybe orientation doesn't matter?
Thanks all!!
I would mount the water separator vertically in line to the gun rather than try to attach it to the gun. Pressure regulator should be downstream of the separator, at the gun is OK.
 

gilee

Sprinter T1N Camper
I would mount the water separator vertically in line to the gun rather than try to attach it to the gun. Pressure regulator should be downstream of the separator, at the gun is OK.
I will mount water seperator near the compressor, then hose, and the regulator right at the gun.
Thank you!

Now, i am just waiting on thr epoxy primer amd raptor to arrive.
 

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