How to stop surface rust????

[johnmc]

Is there any body guys here?
I have a new cab project that has some surface rust.I have blasted them 3 years ago then used 2 coats of POR. Then painted it with 3 coats of good paint. but it still came back. I need help here i need this to stop.
In some places i blasted then primer ed it. but i didnt wanted a nice finish so i filled the blasted rust with green filler. then 2 coats of POR. then paint. but it didn't last 1 year.
Its not quite a square body but it has some square corners.
pic is before and after 4 years ago after it was done up. The cab needs to be done again.

 

[foamypirate]

Is there any body guys here?
I have a new cab project that has some surface rust.I have blasted them 3 years ago then used 2 coats of POR. Then painted it with 3 coats of good paint. but it still came back. I need help here i need this to stop.
In some places i blasted then primer ed it. but i didnt wanted a nice finish so i filled the blasted rust with green filler. then 2 coats of POR. then paint. but it didn't last 1 year.
Its not quite a square body but it has some square corners.
pic is before and after 4 years ago after it was done up. The cab needs to be done again.

I would think the issue came from the filler. You really need to put the POR on bare metal, and then do any bodywork over the POR if you can. The body filler can hold moisture, which will allow rust to form under the POR.

 

[bucket]

I would think the issue came from the filler. You really need to put the POR on bare metal, and then do any bodywork over the POR if you can. The body filler can hold moisture, which will allow rust to form under the POR.

Agreed.

 

[Old77]

Will the body filler adhere to the POR??

 

[johnmc]

I was thinking the filler was the problem also.I don't feel the filler will stick to por ether . I want to stop the rust for good and I don't think it is possible In the conditions I run this truck.

 

[foamypirate]

Found this on the Por-15 website in this document ( http://www.por15.com/Data%20Sheets/POR15ApplicationInfo.pdf):

CAN I USE BODY FILLER OR PUTTY WITH POR-15?
Yes. First paint both sides of the rusted area with POR-15; then use
body fi ller or putty as soon as the POR-15 is dry to the touch. For best
results and adhesion use our StraightLine or RestoGrip body fi llers over
POR-15

 

[bucket]

Put on a few coats of the POR. When it's fully dry, lightly sand the pitted areas by hand with 80 grit, this way you won't sand through the POR. Then apply filler over the prepped POR.

Also, if you are just wanting to smooth over the pitted areas (not fill dents), use 3M polyester glaze.

 

[johnmc]

Put on a few coats of the POR. When it's fully dry, lightly sand the pitted areas by hand with 80 grit, this way you won't sand through the POR. Then apply filler over the prepped POR.

Also, if you are just wanting to smooth over the pitted areas (not fill dents), use 3M polyester glaze.

3M polyester glaze is where I has my first problems with bubbling on pinholes.but i dont rember if I put por 15 under or over. but it failed bad

 

[Old77]

Put on a few coats of the POR. When it's fully dry, lightly sand the pitted areas by hand with 80 grit, this way you won't sand through the POR. Then apply filler over the prepped POR.

Also, if you are just wanting to smooth over the pitted areas (not fill dents), use 3M polyester glaze.

^^this....I used fiberlass in a few spots on the truck and used Metal Glaze (evercoat's version) and it REALLY smooths things over nicely!!!

 

[bucket]

3M polyester glaze is where I has my first problems with bubbling on pinholes.but i dont rember if I put por 15 under or over. but it failed bad

I'm sure you must have put it over the rust, under the POR. The only chance of killing the rust (other than cutting it out) is to get ALL the loose scaly stuff off, coat it with POR, and do not sand through the POR anywhere. If there's any pinholes in the metal, it's too far gone and the rust will come back.

 

[89Suburban]

You must be registered for see images

 

[johnmc]

sand blasted the surface rust then primed with oxide primer then 3m green glaze then por 15 over that . It wasn't bad rust but I didn't want it to come back .I am telling you in different places I sand blasted it then 2 coats of por 15 then 2 coats of paint and it is back .4 years later.I have also done some rust converter stuff there must be a better way.
thanks guys

 

[bucket]

The POR has to be put directly on the metal, with nothing in between.

Unfortunately, there's no sure fire way of eliminating the rust. It's even harder to fix the surface rust if it's bad enough to require filler to make it smooth. That's why the POR instructions say to coat both sides of the metal. If there's a significant amount of pitting, the metal can be porous and letting moisture come in from the back side.

I don't suppose you have pictures of what the rust looked like before you started?

 

[bucket]

I forgot one more thing. There's a product I've been using lately that is very similar to POR-15. It's stronger, seems more reliable, dries faster, and it's cheaper too. I just don't remember the name of it (had to pitch the original can it came in), but I'll try to find out what it is.

 

[johnmc]

I forgot one more thing. There's a product I've been using lately that is very similar to POR-15. It's stronger, seems more reliable, dries faster, and it's cheaper too. I just don't remember the name of it (had to pitch the original can it came in), but I'll try to find out what it is.

was it magnet paint? chassis coat?