HVLP Help (1 Viewer)

[LazarusTaxa]

I'm hoping anyone with some experience might be able to answer a few questions and provide some guidance.

I've taken the body off my FJ60 and am in the process of wire wheeling off all the existing undercoating and rust.. Getting it down to bare metal and a few patches of well adhered factory paint. See here for a partially completed pic:

I am then going to coat the bottom side of the body and front fender liners in raptor liner (or similar if anyone has other suggestions). I was going to have this done by a local shop, but them increasing their quote to $3,500 means I'll be tackling this myself.

My plan is to shoot some PPG epoxy primer down, use 3M urethane seam sealer on all the seams, cover that with more epoxy primer, and then put down the raptor liner. This is the bottom of the truck, so I'm not very concerned with aesthetics.. Just quality and durability. I dont need it to look good, just last a long time.

My concerns though are about equipment. My idea is to use the standard harbor freight purple gun, which i've had good results with shooting contact adhesive. Any issues here? HF says it needs 6 CFM, but that seems way low.. I assume more like 13? I cant see what kind of airflow the raptor gun needs, but reviews seem to suggest ~6 CFM @ 60 PSI.

For air supply, I'm limited to my small pancake compressor (maybe 2.4 CFM?) and my neighbors compressor (maybe 4 CFM?)..

If I connect these two together, will that get me enough air to shoot primer and the raptor liner? Again, if I was shooting color and clear and concerned with aesthetics I'd worry about having continuous flow to keep a wet edge. But here I just want to stick.

I live in a dry area, but would I need to worry about water in the lines? Would a cheapo filter like this one work for me?

Anything else I should consider?

 

[LazarusTaxa]

Also, I realized I can rent an 8 gallon gas wheelbarrow type compressor which will provide around 11 CFM at 90 PSI. I know the tank isn't big, and it will be running the whole time, but would that work?

 

[LazarusTaxa]

Ok, one more question..

I've got 99% of the undercoating, lose paint, etc stripped. But, I'm having a super hard time getting all the nooks and crannies of the bottom of the body where all my various sized wire wheels don't fit. See circled areas here:

There is a bit of rust and undercoating still in the corners where I cant get to with circular objects.. How can I strip that stuff out? Anyone have any suggestions?


OR, if I can get all the minor surface rust off, will a good epoxy primer cover and adhere well enough to the small bits of undercoating that are like on the back side of the brackets I can't reach?

 

[RUSH55]

How about a small siphon sandblaster to clean out those small, hard-to-get spots?

I would definitely be paranoid about water in the system while painting with a smaller compressor that is continually running. Put a dryer on the output of the compressor with a new hose and a filter on the gun.

 

[LazarusTaxa]

How about a small siphon sandblaster to clean out those small, hard-to-get spots?

I would definitely be paranoid about water in the system while painting with a smaller compressor that is continually running. Put a dryer on the output of the compressor with a new hose and a filter on the gun.

Yeah, I tried getting one of those HF handheld guns and my finish nailing compressor is def not up to the job. Also, maybe more relevant, tilting the gun back to aim at these spots means all the media slides back in the hopper and doesn't fall down the chute to the nozzle.

I'll try a dremel and elbow grease...

Will water in the system prevent the primer from setting properly? I know it's epoxy based, so not sure how that will actually affect the mechanical adhesion?

 

[RUSH55]

ALC Portable Abrasive Siphon Blaster 50-Lb. Capacity, Model# 41017 | Northern Tool

This ALC® Portable Abrasive Siphon Blaster holds up to 50 lbs. of abrasives and is perfect for a wide variety of surface preparation jobs ...

m.northerntool.com

Blaster like this, not one of those little gun type you’re thinking about.

Water/moisture in the mix will absolutely affect adhesion despite epoxy in the paint. You’re sealing moisture to the metal. It starts the corrosion process.

 

[LazarusTaxa]

Blaster like this, not one of those little gun type you’re thinking about.

Water/moisture in the mix will absolutely affect adhesion despite epoxy in the paint. You’re sealing moisture to the metal. It starts the corrosion process.

Yeah, that looks a lot better.. Maybe I'll have to invest.

As for painting, I think I'm gonna rent the 8 gallon gas powered 14 CFM compressor. I'll coil one line and run it through icy water before an oil/water separator. Then another line into my gun with another dryer at the gun.

I think that should do the trick?

Any thoughts on the necessity to ensure ALL little bits of undercoating are removed? I would think that if the substrate is well adhered (old paint, primer, or even undercoating) the primer would be fine going over it?

 

[RUSH55]

Any thoughts on the necessity to ensure ALL little bits of undercoating are removed? I would think that if the substrate is well adhered (old paint, primer, or even undercoating) the primer would be fine going over it?

Clean it as thoroughly as possible with acetone and lint-free cloths.

 

[CenTXFJ60]

Just read through your posts and looks like you're getting the compressor situation figured out. Rush55 has provided some great feedback as well. As for those hard to reach locations, can you get some different variations of picks and pick and chisel your way to metal? I would also use a rust neutralizer during the prep process. I use OSPHO but there are many good variations out there. Good luck and look forward to following along.

 

[LazarusTaxa]

Just read through your posts and looks like you're getting the compressor situation figured out. Rush55 has provided some great feedback as well. As for those hard to reach locations, can you get some different variations of picks and pick and chisel your way to metal? I would also use a rust neutralizer during the prep process. I use OSPHO but there are many good variations out there. Good luck and look forward to following along.

Awesome, thanks.. I've been following your painting and build threads as well. I'm hopefully gonna have some time this weekend to get the body cleaned up the rest of the way.. I'm sure I'll have a few questions as I get closer.

 

[CenTXFJ60]

Awesome, thanks.. I've been following your painting and build threads as well. I'm hopefully gonna have some time this weekend to get the body cleaned up the rest of the way.. I'm sure I'll have a few questions as I get closer.

Wonderful. My cell is 713-805-3962. You're always welcome to call/text if that's easier.

 

[PAToyota]

For the hard to reach spots, something like this for a drill works great.

Amazon product ASIN B081JSTQ4Y
I second CenTXFJ60's recommendation on rust neutralizer. I use this with good results: Gemplers Rust Converter, 1 gal. - https://gemplers.com/products/gemplers-rust-converter-1-gal

In fact, I have a test going on where I just used a scotchbrite pad on rust to clean it up a bit, wiped it down with acetone, and then applied the Gempler's onto it with no top coat. Six months of snow, ice, and rain and there is no sign of rust coming through. I'm pretty amazed by it without a top coat.

Sounds like you have the compressor sorted out, but the bigger the compressor, the less it has to work, which keeps the air cooler and therefore dryer. Moisture in any paint is no bueno... Even with urethane, it speeds up curing and causes all sorts of problems.

 

[LazarusTaxa]

OK, I rented the gas compressor.. It's something like 16 CFM @ 90 PSI, so plenty of air moving. But, when using my hand held sand blaster for an extended period (I rigged mine up work like the one @RUSH55 recommended), there's definitely some water in the air.

That's directly from the compressor, so no cooling or water trap yet.. I need to go pick up a dryer from HF and get that installed.

But, the ghetto sandblaster works surprisingly well.. It's getting all the nooks and crevasses I can't reach with any kind of wire brush. Its SUPER messy though. I was wearing safety goggles, the hood from my jacket, and then a face shield over that (with a 3M P100 respirator of course) and still got plenty of grit in my eyes. An actual hood would be advised.

I'm getting close to painting and have ordered all the supplies needed. If I can get my welder over to patch this rust in the wheel well in the next couple of days, I hope to do the painting this weekend.

I've got some 3M Heavy Body 2K seam sealer coming and planning to cover every seam I can find on the bottom of the truck. Interestingly, most were bare from the factory. I do have a question for you guys (@CenTXFJ60 and @PAToyota included).. Any tips on seam sealing edge seams like these:

There isnt much there to glob the sealer on to, and for the fender/body seam, it's gonna be semi-visible. Do I just press as much into the seam as I can and wipe off the extra?

I'm also a bit nervous about the sealing b/c this stuff apparently only has like a 15 min working time, so not a lot of time for fixing errors.

 

[CenTXFJ60]

Man…you’re going to town on this rig . As for the pinch weld on the wheel we’ll return, that would be a tough one. To your point, any excess would be visible on the outside, I’d use the fast line product in this pic. I’ve used the 3m stuff before and it’s much stickier and harder to work with once dispensed.

 

[LazarusTaxa]

Man…you’re going to town on this rig .

Yeah, I won't be sad when I'm done painting the bottom of this thing.. Painting prep is long, tedious, and hard work.. I don't even know how much time I have in it so far but at least 20 hours probably. I will be happy to outsource the actual painting of the body if an when that day comes.


I've already got the 3M stuff, and, being a 2K product, it's supposed to be a lot more durable than single part. I'll just work in small sections and use masking tape.

 

[RUSH55]

It’s tedious, but the extra effort will be worth it. After you’ve cleaned it as good as you can possibly get it (acetone wipe down after all your prep work) spray your epoxy primer. Use several before mentioned methods to filter the air and keep it dry as possible. Once you’ve laid down a couple coats of primer, seam seal with a two-part sealer, and then lay another couple coats of epoxy primer or 2K primer. (I’ve used both single part and two part seam sealers and there really is no comparison. It costs more and requires a special applicator gun, but it’s well worth it to just bite the bullet and go this route).
Once you’re done there, blast away with the bed liner or whatever it was you were planning to use under there.