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coating underchassis (not sandblasted...so mix of surfaces)?

T

tp85

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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? Hoping 3M undercoating will stick like snot.

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?

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por15 and rust bullet are encapsilators.. i prefer converters for rust.. bare metal should ALWAYS be primed.. always.. even if your just gonna douche it with undercoating..

oh, and your pics don't work...
 
kind of leaning towards POR15 unless someone can talk me out of it.

i've used some rust converters that have eventually blistered. a little hesitant to go this route again.

either way, my concern is getting whatever coating to adhere. prepping detail hell. clean, abrasive, clean, repeat, repeat, ... while looking forward to more enjoyable drivetrain and suspension work.
 
tp85 said:
kind of leaning towards POR15 unless someone can talk me out of it.

i've used some rust converters that have eventually blistered. a little hesitant to go this route again.

either way, my concern is getting whatever coating to adhere. prepping detail hell. clean, abrasive, clean, repeat, repeat, ... while looking forward to more enjoyable drivetrain and suspension work.
Click to expand...

I was just looking at the POR-15's website trying to figure out how to treat rust inside my boat trailer frame......

Anyways, after reading a lot of comments, one thing that came out was the ability for POR to adhear to "clean metal". Quite a few stated it worked great when applied directly to rusted areas, but the areas that were clean had difficulty adhearing. That's about as far as I read but worth investigating before going that route.

They also said to "follow the directions" to a tee.....
 
now i am also hearing POR15 can't be used on painted surfaces (even after heavy scuffing).

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 single coating that will do the job.
 
I've got to ask:


Why is sandblasting NOT an option? :thinking:

You've done all the hard work of stripping the cab completely down, and it's even on a rotisserie. Seems like if you can get it out the garage door you could bring it to a specialty place for either sandblasting or sodablasting, get EVERY last ounce of rust out of it and then shoot it immediately with a good urethane primer and be done. :dunno:

I see a whole lot of man-hours left doing it the "hard way", and as you said it still won't be as good as blasting... just curious why you put that restriction on yourself.

-G
 
I concur with Greg.

Years ago I worked for WARN and we were having issues with powdercoating failing on the large HD bumpers. After doing an extensive research project with another engineer, evaluating how best to solve the problem, with months of salt spray testing within a lab, sandblasting was the recommended cheapest/best option. Chemically stripping with a zinc phosphate undercoating was the second best option but cost more.

Sandblasting is one of the preferred first steps for coating of American military products as well.


Sand blasting or chemically stripping is the only way you can be sure the base metal is absolutely clean - anything less is risking that some contaminant that was missed will rear its ugly head with flaking paint in the future. With a 40 year old truck, chances are good that something that will propogate corrosion is lurking somewhere under that body.


I have a buddy who owns a mobile sand blasting company - he often will travel to people's driveways and blast project cars at their home. Might look to see if there is such a thing in your area. :waytogo:
 
I would do sandblast, then primer, then por-15 with a coat of bedliner on top of that. Should last a good long time and have multiple barriers. Por-15 sticks just fine to clean metal, i did my whole floor in it and the topper sealing surface anfter blasting most all of it clean. The stuff dries hard as a rock. It just takes like 5 hours to dry which sucks.
 
And fyi sandblasting is going to get farther into any nook and cranny than what your doing and will always work the best. :whistle:
 
ah geez guys...telling me what i didn't want to hear! :D

i'll bite the bullet, and at least get some price quotes. i know one guy who is mobile with a soda blaster. comes to your home for the job.

if i soda blast the underchassis, is it a good time to do the whole body? i really hadn't planned to finish the body until much later (like a year or more). but i guess i could shoot the bare metal with an epoxy primer until i am ready to start the body work.

after the underchassis, i really wanted to finish the frame, suspension, drivetrain, etc. to get back on the road. tired of this pile of blazer parts in my garage. i'd at least like to be able to drive it to get milk or ice cream sooner than later.
tom
 
Id just do the underside now, you can do the rest later and drive it to a place and have it done at a cheap price prolly.
 
Yeah por15 needs metal... Straight from the manufacturer.
 
ryoken said:
;)



I've never been known for my tact... :doah: :haha:
Click to expand...


I was waiting for you to respond.

POR is an abbreviation for "Paint Over Rust"... I guess people forget that sometimes. Kind of defeats the purpose to put it on top of primer.... I'd guess it isnt even all that great to put over clean, rust-free metal. :dunno:

In any case, I've been attending the "Church of Ryoken" for several years now, and the worshippers there don't believe in POR-15 at all.... do it right, and do it once. :thumb:


-G
 
I used it on various surfaces and it sticks just fine. Say what you want but i like it. The hitch i blasted and sprayed self etching primer on and then painted with POR-15 a year ago still is spotless and rock hard, so dont tell me it doesnt work till you try it yourself.:waytogo:
 
I've only been using POR15 since you where in diapers.. :rolleyes: literally, been using that stuff since the early 90's...

IT'S AN ENCAPSILATING PRIMER, why would it be advisable to put a primer on a primer? :dunno:
 
Because if it chips there is still primer underneath it lending some protection from the elements. Im not saying its not what its meant for what it says on the label, im saying ive used it on primer and on clean metal surfaces and it worked fine. You guys dont have to like it but i do and im going to use it more. Just my 2 cents, take it or leave it. No need to degrade me over it
 
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