mixed surfaces underchassis coating dilemma - what will ADHERE best?

[tp85]

Ok, blazer tub tipped, plus many days of scraping the underchassis. Next I am going to use some solvent cleaner, abrasive disks, wire wheels, and more solvent cleaners. Sandblasting is not an option. No matter how hard I try, there will be plenty nooks and crannies that will be unscrapped and too dirty for paint to adhere. It is going to be impossible to get everything paintable squeaky clean...thick oil, dirt, cracked undercoating, waxy slime, and what ever else they spray in farm country to prevent rust.

As you can see in the photos, I have a mix of surfaces ----- surface rust, OE painted, new patches, and bare metal. On rusted areas, I will use a rust converter first.

My big question is what will adhere best --- 3M undercoating or Eastwood Rust Encapsulator (or POR 15)? It seems to me that Rust Encapsulator is like a paint and will likely peel if the surface is not squeaky clean. In contrast, I would like to think a 'tar-like' undercoating would adhere better on less than optimally clean surfaces. Is this correct?

For fear of Rust Encapsulator or equivalent peeling within a short period, I am leaning towards just treating rusty areas with a rust converter, and then using 3M undercoating everywhere (bare metal, painted surfaces, rust converted areas, etc.). What do you guys think?

[scapegoat67]

Spray the bare metal with epoxy primer first . Then I would brush on POR 15 . It will look you you sprayed it . Very messy to work with . Wear you oldest clothes and gloves . If you get any on your skin , it takes days to remove .

[tp85]

How good is the 3M (or equivalent) undercoating?
Does it stick like 'snot'?
Really can't imaging a paint-like product (epoxy, encapsulator, POR-15) working well in all the inaccessible nooks and crannies.

[tp85]

what does everyone do? i doubt everyone sandblasts.
i'd like to tackle this job over the next week, and would appreciate any feedback.

don't worry, i won't track you down if the coating peels off in sheets.
tom

[Cracksrubi]

Media blasting
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[71 super]

Dont use encapsulator it is not as good as por15. I would spray an epoxy primer or por to seal and use the 3m to top coat and add a bit more protection. The 3m will hide the welds of the patches and is a good product. POR likes a surface it can "bite" into (P -paint O over R Rust) it does not do well with a slick finished surface and you can get it into the nooks and crannies with brushes of different sizes.

[Fitz]

Media blast or rust converter, spray with epoxy primer then...Rhino-Liner

[Sonoma10714]

^^^^ agree
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[tp85]

If I use POR-15, how do I prep painted surfaces? How to put POR-15 on painted surfaces? I would not be interested in stripping all the OE paint where it is in good condition.
Tom

Originally Posted by 71 super

Dont use encapsulator it is not as good as por15. I would spray an epoxy primer or por to seal and use the 3m to top coat and add a bit more protection. The 3m will hide the welds of the patches and is a good product. POR likes a surface it can "bite" into (P -paint O over R Rust) it does not do well with a slick finished surface and you can get it into the nooks and crannies with brushes of different sizes.

[tp85]

Which rust converter is best? I have recently found many bad reports on Eastwoods rust converter not dying properly and causing blisters in the top coat???

Originally Posted by Fitz

Media blast or rust converter, spray with epoxy primer then...Rhino-Liner

[notsolo]

1st your tub is looking great..I like Mastercoat silver with U-PoL raptor bed liner....I like the Tintable with your choice Urethane base coat color.... www.masterseriescoatings.com

[72cheyenneman]

This is what I did to mine. Sandblasted, used lacquer with a putty knife, wire wheel, brush, anything I could find..you name it, I used it. As far as paint, it's an epoxy primer with a top coat. Take your time and do a good job--it's worth it.

[71 super]

Scuff the wee wee out of the old paint for the por to bite youse the wire brush on drill you might be better off just using straight 3m or a liner type material
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[tp85]

Beautiful work there...yes, I think the key is not rushing. Gotta resist the urge to rush to move on to the drivetrain.

Originally Posted by 72cheyenneman

This is what I did to mine. Sandblasted, used lacquer with a putty knife, wire wheel, brush, anything I could find..you name it, I used it. As far as paint, it's an epoxy primer with a top coat. Take your time and do a good job--it's worth it.

[tp85]

Because I am not going to sand or media blast, it is starting to seem like POR15 may be the best choice because of the mix patches of rust, clean metal, and paint.

Sounds like if I really scuff up the painted areas and follow the POR15 instructions on the rusted and non-rusted bare metal, then POR15 can be used everywhere...which will simplify things.

Large area for POR15 (with all the specific instructions and re-coat times)...I wonder if I should break it down into smaller areas instead of doing the entire tub all at once. I'll probably brush on since it seems to level really well, but I could also spray.

Thoughts? Shoot me down if I am on the wrong track...I'll thank you later.
Tom

[tp85]

I'll check this stuff out, but I don't think this is a time at which I want to experiment. Is the masterseriescoatings used a lot by forum members?

Originally Posted by notsolo

1st your tub is looking great..I like Mastercoat silver with U-PoL raptor bed liner....I like the Tintable with your choice Urethane base coat color.... www.masterseriescoatings.com

[mrein3]

I'd be real tempted to apply a good coat of Dupont or PPG surface prep stuff. I wish I had a number handy for you. I've used basically the same product from both suppliers.

What they have is an acid product that you brush/spray/spong on, wash off with water, then blow dry with your air nozzel. I've used this under PPG epoxy on many projects and have NEVER seen anything bubble back through the paint/epoxy.

I believe the trick is the acid gets in the pores that are created by oxidation. In other words you wouldn't use this on new metal, just older metal that had the surface rust removed. If it gets on a new piece you welded in, it won't hurt it. You just wouldn't do this treatment on say a whole new replacement fender with zero rust on it.

[1972SUPERSB]

I use the 3M undercoating and it works great. I clean it as good as I can then spray it on. Sticks very well and dries to a sandpaper like finish.
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[fxdxharley]

1.first you need to clean everything very well. like pressure wash it.
2.then use prep cleaner or wax and grease remover.
3.then por 15 the rusty areas.
4. then epoxy prime everything else
5. u-pol or 3m undercoating (just dont put the undercoating on to thick it will lift off. a nice even layer), or ryno line etc.
6. of coarse you can still top coat every thing in step 5 with a nice urethane paint.

[tp85]

after POR15'ing the entire underchassis...
what are the advantages of 3M undercoating?
disadvantages?

[tp85]

Just got off the phone with POR15.

can't use POR 15 over scuffed paint?!

so if i want to use POR15, i need to remove all the OE paint...not a great idea since i am not media blasting.

i was hoping to find a single coating which could be used on rust, clean bare metal, and scuffed OE paint.

so far, i don't think there is a 'manufacturer-guaranteed' single coating that will do the job.

[Sonoma10714]

Clean it the best you can with a wire wheels/sander/ ect and then degrease it all and dry. Epoxy prime it it you want and then line-x or rhino line it. Just my opinion.

You can't use por15 over old paint.
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