How much rust can under-body spray stop?

[ovrszd]

And the snow/ice vary's quite a bit from northern Missouri where Richard lives from down here in extreme southern Missouri where I live. We use even less salt, and probably by a large margin. We also use beet juice down here instead of salt for a pre treatment or so I have heard. Not saying we can't have some rust problems, but I don't think it is the problem that you guys up north have or even Northern Missouri would have.

Definitely. I think, for Missouri, that's why the data chart that Moss posted is skewed. Missouri's corrosive treatment is used on a very, very small percentage of their total State roads.

I made a trip to Ft Leonard Wood to pick up some Hummers several years ago. They had received 12" of snow down there the night before. They were removing snow from the State Hiway with an end loader!!!!! Guess there must have been a shortage of snow removal equipment in that area??

 

[arkydog]

3m carried the same stuff. probable just like krown's. i watched the video and its no different from the way that that cars were "rustproofed" in the 80's and early 90's when some of the new car dealerships were selling a rustproofing package they installed on new cars just like krowns. this package was a big money maker for them. i'll try to remember the name of the stuff later. something "shield", just like what z-bart was doing and you see where they are today. 3m also made an interior and exterior rustproofing that is to be applied "after" body work was performed. the insurance institute also recommended this done on any body work area just like crown, but only on the repaired area.

it was also noted that this wasn't necessary on new cars because the manufactures made it not necessary because of the manufacturing process with galvanized panels, better primers and better electro-plating, and a huge difference in the paints. also most people don't know that a lot of manufactures use a closed cell foam in special places to sound deaden the car which makes it impossible to rustproof those areas and connecting areas.

it is also said "some's good, more's better, and too much is just enough".

if you do decide to to have crown's or similar done, there is a sure way to repair any plug holes they drill. just go to the store and buy some good spray primer, a color close to your car color, and a small artist paint brush.

1. remove the plug by sliding a SMALL screwdriver under the edge of the plug and into the drilled hole and pop out the plug. if the plug distorts just heat them with a hair drier or butane lighter till they go back in shape.

2. use some wax and grease remover (have to say this but rubbing alcohol works just fine) and liberally clean the hole and bare metal area.

3. shake primer and spray into the primer can cap. using the artist brush (the fuzzy end after removing from the book of a paper match stick works just as well) and coat the bare metal areas of hole and let dry.

4. shake paint can color and proceed same as above. only one or two coats, the thinner the better and let dry real good, don't rush.

5. install plug and your protected.

 

[k0ua]

Definitely. I think, for Missouri, that's why the data chart that Moss posted is skewed. Missouri's corrosive treatment is used on a very, very small percentage of their total State roads.

I made a trip to Ft Leonard Wood to pick up some Hummers several years ago. They had received 12" of snow down there the night before. They were removing snow from the State Hiway with an end loader!!!!! Guess there must have been a shortage of snow removal equipment in that area??

A 12 inch snow down here in Branson would be a show stopper literally. We get all excited with a 6 inch snow.

 

[Scooby074]

Scoob, how do you apply it, and what would you say it is similar to, undercoating that hardens or FF?
Do you remember what a 5g bucket costs?

Ill grab a pic of my setup when im in the shop. But basically its an Arslan sprayer (sold by many companies under various names, NAPA for one). I made some custom wands to reach up inside the box sides and other places. You can buy them too, but Im cheap.

The product is similar to bulk FF when in the bucket. Very gel like. When sprayed it goes areasol and leave a fine, oily, slightly sticky film, NOT a sticky gel blob like FF does.

5gal was a couple hundred bucks ($225-250 maybe??). But that is enough to do a few cars no problem.

 

[aeblank]

Krown doesn't seem to be anywhere near as available as Fluid Film.
I don't see where I can get a gallon of Krown. I can get one on amazon for FF.
Preference for one over the other?

Also pondering the difference between the generic "undercoat applicator" for $20 and the FF one for $90.

 

[ray66v]

if you do decide to to have crown's or similar done, there is a sure way to repair any plug holes they drill. just go to the store and buy some good spray primer, a color close to your car color, and a small artist paint brush.

1. remove the plug by sliding a SMALL screwdriver under the edge of the plug and into the drilled hole and pop out the plug. if the plug distorts just heat them with a hair drier or butane lighter till they go back in shape.

2. use some wax and grease remover (have to say this but rubbing alcohol works just fine) and liberally clean the hole and bare metal area.

3. shake primer and spray into the primer can cap. using the artist brush (the fuzzy end after removing from the book of a paper match stick works just as well) and coat the bare metal areas of hole and let dry.

4. shake paint can color and proceed same as above. only one or two coats, the thinner the better and let dry real good, don't rush.

5. install plug and your protected.

That would certainly be better than nothing.

But, it takes a lot more than a spray can primer to properly protect metal.

First, primers are much more porous than top coats. And provide very limited corrosion protection. If you have ever seen a car where someone sanded a bunch of spots and just primered them, at some point, the rust stains eventually start showing as rust comes right through every primer spot. This is because its not a good moisture barrier, by it's self.

Secondly, drill holes create very sharp edges. And, sharp edges are very difficult to build paint film up on. You can see this, by taking something like a lawn mower blade and trying to paint the sharpened edge. No matter how much paint you spray at it, it moves off the sharp edge. So, even if you carefully paint each hole, (and I have sprayed a ton of them), you still have very little film build on the sharp edge, on each side of the hole. So, you still only have a slight amount of corrosion protection.

When parts are stamped, care is taken to avoid creating sharp edges, so they don't have the same problem. They also use electrostatic spray equipment, that causes paint to be applied more evenly more.

Believe me, I have tried everything imaginable on these holes over the years.

The most effective thing I have found, which was still limited, is window weld primer. This product is designed to protect the metal under your glass, when it's glued in. 3M Single Step Primer 8682

As I said, I hope the rustproofers have found an actual solution to this problem.

If not, personally, I would not allow any holes drilled in my car.

 

[ray66v]

This company makes inexpensive equipment to do your own undercoating, and rustproofing.
RUSFRE Undercoating Kit - TP Tools & Equipment

Rusfre Rust Proofing

I have owned one of these guns, for many years.

The gun sprays both undercoating, or rustproofing, and has a long nozzle to shoot the product deep into the panels.

Their undercoating, is by far, the best I have ever used. When it sets up, it's smooth, and shinny. Don't try to spray it through the flexible wand, you don't normally need to. Anything you can't get with just the gun, use the wand , and spray the rustproofing in side it.

A gallon of each, should do most vehicles, with some to spare.

They also make an aerosol rustproofing kit, I have not used. Rusfre Inner Panel Cavity Wax Rustproofing Kit MD 16 | eBay

 

[Luke'sScreenName]

That would certainly be better than nothing.

But, it takes a lot more than a spray can primer to properly protect metal.

First, primers are much more porous than top coats. And provide very limited corrosion protection. If you have ever seen a car where someone sanded a bunch of spots and just primered them, at some point, the rust stains eventually start showing as rust comes right through every primer spot. This is because its not a good moisture barrier, by it's self.

Secondly, drill holes create very sharp edges. And, sharp edges are very difficult to build paint film up on. You can see this, by taking something like a lawn mower blade and trying to paint the sharpened edge. No matter how much paint you spray at it, it moves off the sharp edge. So, even if you carefully paint each hole, (and I have sprayed a ton of them), you still have very little film build on the sharp edge, on each side of the hole. So, you still only have a slight amount of corrosion protection.

When parts are stamped, care is taken to avoid creating sharp edges, so they don't have the same problem. They also use electrostatic spray equipment, that causes paint to be applied more evenly more.

Believe me, I have tried everything imaginable on these holes over the years.

The most effective thing I have found, which was still limited, is window weld primer. This product is designed to protect the metal under your glass, when it's glued in. 3M Single Step Primer 8682

As I said, I hope the rustproofers have found an actual solution to this problem.

If not, personally, I would not allow any holes drilled in my car.

When I talked to NH Oil Undercoating they said that just about every vehicle 6-7 yrs or newer had enough drain hole to get everything without drilling. Any thoughts?

 

[MossRoad]

Most of your statements above made my case. Missouri has the most miles of State maintained roadways in the Nation. I have no data to support the distribution of their winterizing materials. But rest assured, the Interstate Hiways and numbered national hiways get the vast majority. So if you are one of the unlucky ones that use those roads all the time you are constantly getting salted. If on the other hand you don't use those roads regularly you might qualify as not being exposed to much corrosive material. I would never claim that Missouri has as much hazardous weather as Michigan for example. But don't be na?e and assume Missourians are not exposed to corrosive roadways.

I'm not naive about it. They just don't get anywhere near the amount of exposure as Michigan. Its not even close.

 

[coobie]

I'm not naive about it. They just don't get anywhere near the amount of exposure as Michigan. Its not even close.

Plus +1 moss..