POR-15 or sandblast?

[ctjeepman]

I'm going to be be ripping apart the beast soon and want to know if I should bother sandblasting it before I put on something like POR-15? As I understand it I don't really need to with this product because it just seals in the rust completely. I was planning on doing the whole frame and inner engine compartment and undersides of both the cab and bed, maybe the bed inside too!

[FSJeeper]

I would go totally with POR. Not only does it seal the rust, it converts it and gets better with age and the elements.

[Cliff]

POR seals better to a rusty surface, according to the company. I remove heavy rust, and sometimes keep rusty areas wet with Ospho for a few days before applying POR. I have had POR peel from a heavily rusted battery tray. It also does not resist battery acid vapors. I used POR extensively on rust free parts, topcoating with the color of choice. So far no problems. I apply the topcoat while the POR is tacky.

[ctjeepman]

what is ospho?

[FSJeeper]

Originally posted by dadisdman:
what is ospho?OSHPO is a green colored oxidizer that has been around forever. I have used it for years. I use it on light surface rust and it works great. For heavy rust I use POR.

[Ralph]

I don't doubt that POR-15 and similar products are excellent at what they're supposed to do. But I know that even a tiny speck of oxidation on bare metal can start a spider web of rust running underneath a good paint job.

So I would recommend that if you have the equipment and a good place to sandblast, that you do that first. Then if you want to seal the metal with POR-15, why, you'd get the best of both worlds.

Another note: POR-15 breaks down with continued exposure to sunlight/UV, so its use should be restricted to such areas as the frame and underbody, or else you should topcoat it. I've been told that it cures pretty hard such that sanding it (to get more surface area for topcoating to adhere to) can be quite a chore.

[Damage, Inc.]

There's alot of POR fans here so I'm probably going to get flamed for this...but...
Every piece on my Jeep is getting rust-proofed. It's 28 years old and definitely needs it. Some people use POR to cover up rust and avoid dealing with it. My feeling on that is that I'd much rather deal with the rust here in my shop than at 13,000 feet when all of your buddies are standing around waiting for you to fix your _______.

[Irondust]

What are you rust proofing it with?

[TexasJ10]

I would go with aluminum oxide blast, the POR chasis coating on the frame, and a spray of POR in all areas that appear rusted, or possibly on the entire area that you are working on. POR recommends a product they sell called Metal Ready, or something like that, that will lightly etch the bare metal and make adhesion of the POR better on bare metal. As it was pointed out above POR likes rusted surfaces to adhere, but it is hard to tell whether you have actually removed all of the loose scale before applying. You have to be real carefu lto leave the surface rought enough for it to bite and apply it at the right tempertures or it will peel. In alot of ways it reminds me of what happens when surface prep isn't good before powder coating. It looks good for a little while then it bubbles and peels. If done right it is hard to remove POR 15.

[Va-Rob]

I agree with Tex on the aluminum oxide blast. Be careful with "sand blasting" some of the grit is to heavy and can actually take too much material off the frame. Check with a local car restoration shop for a good shop to have the frame blasted.

Rob

[greasyjeep]

From experience
If you are applying the POR yourself?
It doesn't like grease - I used a power washer to clean the entire underbody amd frame.
Then went back with a steel brush.
Sprayed the Metal Ready.
Then applied 2 cotes of the POR - make sure you cover yourself from head to toe. It is real tough to get off your skin (steel wool and brush though).
Went pack and sprayed rutolium over it to protect from UV (not really needed except for bumper braces).
I have banded with a hammer and driven a screw driver to try and chip it - no luck yet.

On my 68 olds so it "shouldn't" see any rocks.

Really cover yourself up and plan on throughing away the clothes - double/tripple glove - used a clear face sheild.
Still ended up scrubbing with steel wool and brushes trying to get the stuff off.

[MACKCOOK]

If your going for show car finish, plastic media blast, cutout all rust and weld in clean metal.
if your going for speed and less expense of money and time, use the por and a good primer sealer, preferably a epoxy type. Try and stay away from sand blasting it self because it will still be falling out of places years from now, with rust and moisture attached.

[sloop]

Hammerite is a good rust converter that I use.

www.hammerite.com (http://www.hammerite.com)

you can get it at some True Value hardware stores.. I ordered some from Hamilton Marine.

[bonjohnny]

Havnt tried por yet but have sandblasted extensively on my '48. in simple terms, it sucks! youll find sand weeks later in places you forgot you had!

[LarryD]

I've used POR for years. Never had a problem but you HAVE to follow directions to the letter. Also POR does not 'off gas' like 99.999% of the paints and 'rust converters' on the market. It will change color in UV light but that does NOT degrade the integrity of the product. If used properly, it actually bonds with and becomes part of the metal it is applied to. YES, do get rid of heavy rust. YES, do degrease and YES, thoroughly rinse the metal just derusted. (I know, water on derusted metal doesn't soun right but .....just do it) and THEN thoroughly dry your beast.

POR is not a way to, forget about rust. Sorry, it doesn't work that way. It is the best 'converter' on the market, IF USED AS PER INSTRUCTIONS. It is rock hard too when done.

There are times when media blasting will be better, times for sand blasting (axles, etc), and there will be times when stripper and then treating will be better. Each project demands it's own hugs and kisses.

'84 GW
360
Maroon exterior
Sand interior
85+k miles

'79 VW Cabriolet
Florida blue exterior
White interior
88+k miles

[Smooshy]

I have never been that impressed with POR, and yes I did it right.