VCCA Home Forums TECHNICAL - GENERAL Body - Sheet Metal, Paint & Wood Rust Treatment/Prevention - To Seal or not to Seal

My 64 Impala is in the body shop getting stripped down and painted, and all the rust taken care of (thankfully not much). I have been thinking about how to treat areas on my car that seem likely to be a problem in the future, like where the door skin folds over and is spot welded. I have heard two lines of thought on preserving the sheet metal on the car. One is the POR-15 approach, seal it up tight and to keep oxygen and water out. The other says that it is almost impossible to seal some areas and trying to will just trap what water does get in.

Anybody have experiences with this?

My experience has been that undercoating does more harm than good. When I was a body man back when dirt was young I fixed a lot of rust that happened because undercoat blocked the drain holes. If you add some kind of rust preventer make sure the drain holes are open.

I grew up where it was very common to have the door bottoms gone and holes in the fenders by the time a car was 5 years old due to the heavy salt usage on the roads combined with the humidity.

As Tiny indicated, any "firm" or "adhesive rubber" type of undercoating just tended to hold moisture against the metal and cause hidden rot down the road.

What did work very well was oil. When I was young and poorer it was used motor oil. Auto trans fluid worked very well. I bought a 5 year old japanese car that had a 1" wide opening rusted the full length of the bottom of each door. I oiled the rusty edges of the opening once per year and the doors looked the same 11 years later when I sold the car.

These days I use spray on rust-proofing oil from a spray can. I do this once a year on any venerable areas. The oil seeps into seams and weld corners and will stop or prevent rust as long as there is a thin coating on the metal. I spot spray areas yearly and it works great.

I currently use a product by RUST CHECK in a green can. It's not their thin, running product but it goes on as a watery foam that slowly seeps and runs in about 5 minutes. Any drips are done in a couple days and it wipes off paint without any damage. It is available in a quart can as well and you can use a Shutz gun and a compressor but it's messy (yep tried it!). There are other products by different companies that work just as well but you have to search for it. Check with several body shop supply stores to see what they carry.

I suppose it is worth noting that I live in Southern California and the car has had undercoating on it all it's life. I did not observe any rust related to the undercoating. But being a California car all it's life helps keep the rust down in general.

I like the idea of the penetrating oil like stuff, if only that could then be sealed in with something like POR-15

I have limited experience with "rust" preventative products or sealers.

But I used Por15 on the undercarriage area's, floor pans, sheet metal, frame, interior floors and inside of the trunk of my 41 Coupe. Por15 was easy to use and still looks great after 2.5 years.

I will say this, FOLLOW THE INSTRUCTIONS carefully. One point they make is correct, "it will take 30 days to wear off your hands." So gloves {with out a hole in them} are a MUST!!

Before I applied the por15, I scraped, sanded, wire brushed, cleaned all the areas that were going to be "painted."

I used a combo if spray cans and brush-on and they both went on well. I was even able to connect the red-tube that comes with WD-40 to the spray can to get por15 into some small areas, but you gotta work/spray fast.

Enjoy,
Michael41

What a novel concept. You don't suppose it'll catch on do you???

Instructions??? What's that?????

Tiny, that’s funny!! As a side bar to Por15, the “instructions/caution booklet” is about 20 pages.

Now for us guys and following instructions; as a man of science I can attest to the fact that a man’s DNA, does not allow us to find, read, follow or at times, comprehend Instructions. Truth is we are smarter than the guy who wrote the instructions anyway!!

Well truthfully, men do read and follow instructions but I mean really, why do it. All you gotta have is willingness, some time and a big a** hammer.

As they say, “when all else fails, read the instructions.”, that’s what I do.

Enjoy the ride,
Michael41

Being that the floor is as clean as shown in the photo and you live in sunny California and not Wisconsin, POR 15 works well for sealing seams in door flanges, and door bottoms as the capillary action sucks the paint into the seam and seals it up. POR is expensive as are the projects we work on so it depends on where you want to throw the money.

As far as the inner floor construction shown, POR would work but a lower cost alternative is Rustoleum. Don't Laugh, this is a good product at reasonable cost. The secret is to add 1 to 2 fl. oz of the Flood "Penetrol" product to a qt. of Rustoleum primer. This secret additive will enhance adhesion and rust prevention. You can also add Penetrol to the paint but it will decrease the gloss very slightly.

I use both POR and Rustoleum depending on the applications. POR for seams and inside door bottoms, Rustoleum on cosmetic applications such as floors, frames and suspension parts.

Chips in paint from stones can be easily repaired when painted with enamel versus POR.

The Enamel products come in a wider variety of colors and you can mix them together to make varialtions of your own.

Wisconsin weather is harsh, we deal with "real" rust issues up here. P.S. the secret additive was from conversations with experienced paint and coatings chemists that I have known throughout the years. It really Works! Shhhhhhh its a secret ingredient that works and chemically bonds to rust and metal.

I would never put POR in one of my paint guns unless I want to throw it away. Enamels clean up easily with low cost solvents and can be sprayed any time. I can mix up the paint with the reducer and store the mixed product and use it when I need to. Catalysed primers and paints must be used and the gun cleaned before time expires.

Now you have another option to consider, good luck on your project.

P.S. I had sent an engine out for rebuilding that was once painted, I used the additive in the primer as mentioned on the block before I painted it. When they cooked the block in their hot caustic engine cooker, the paint came off but not the primer. That is what made me a true believer in the addiditve. I reprimed the block and painted it with a catalized enamel.

I know I'm probably too late on this subject but the best way to treat bare metal is to first prime it with a thin (wash coat) of etching primer, then caulk ALL the seems with a urethane seem sealer and finish with 2 or 3 coats of 2 part epoxy primer surfacer. (2K)

It is sold by ether gal. or quart and mixed with an activator at 4 to 1 ratio, but now you can also purchase it in rattle cans.
http://www.repaintsupply.com/pd_2_part.cfm

Oops, almost forgot the most important step, apply a generous amount of "3m Rust Free" inside every pnl. you can accesses. It is a "wax" based spray (like Ziebart) and will not harm the finish or dissolve seem sealer as oil will do. It tends to be a bit pricey and comes in various forms including rattle cans, defiantly is your best choice.>

http://www.amazon.com/3M-08998-Rust-Fighter-I-Application/dp/B0038D7GB2 and scroll down.

Where can you find penetrol??

Thanks

Reid

I would say at a locale paint store or hardware store that deals in marine products. I've never used it before, but may possibly be an inexpensive alternative for some applications.

I use 2 part epoxy or urethane products as they "catalyze" and do not evaporate or shrink. Here is a link that defines "penetrol".
http://www.flood.com/paint-additive-solutions/products/view-product.jsp?productId=11