Tundrawolf

I am body- off extending a frame for an 05 express van that will have a covered utility bed on the back.

The van is also being converted for 4x4.

Presently, the frame has been completely stripped and is in my shop.

I am curious as to, what primer is best for resisting rust, and what undercoating is most durable, as I plan on touring the country and some areas use heavy salt on the roads.

I had read about a high zinc primer, being tested at some salt water docks, and how the primer alone prevented rust better than a different non zinc primer and paint combined.

I have tested high zinc cold galvanizing primer on the frame and it seems to work well.

What are the thoughts? I may not have the body off of the frame again, so I want to do a good job on rust proofing and durability.

The stock GM frame coating is abysmal.

I am also wondering how much primer, and coating to buy. I heard rolling it on saves 30 percent of paint compared to spraying. At $135 a quarter for some of the primers I have seen, I'd rather not waste thirty percent.

How many quarts to paint a 135 inch wheelbase frame, with an additional five feet of frame, welded and gusseted in, for primer, and undercoating?

I will return here after my research and work have been done, and share my results.

I am more interested in a high zinc primer or galvanizing compound, rather than a traditional automotive primer, if the high zinc will be better for rust issues.


Thanks

Triaged

Tundrawolf

Wonderful, informative, and cost effective

Thank you

VanKo

Painting/coating in heavy salt areas is not as effective as one might think. When you paint, you're essentially creating a "shell" around the steel. That shell will eventually be penetrated by salt/rocks/debris - these penetrations or holes will allow moisture into that shell. The paint will effectively trap that moisture and salt and cause accelerated rusting that you may not even be able to see between the paint and the steel. Oil-based undercoatings are superior in this regard, as the oil soaks into the steel and protects it from moisture and oxygen, the two elements required for rust. I do a heavy, thorough oil coat in the fall and it gets me through the winter. The next spring/summer, I will purposely drive in a rainstorm on the interstate for 30 min or so to flush out any remaining salt a few times, then have it coated again in the fall. This has served me well for several years and I have no frame rust. There are a few coatings on the market specifically designed for this. FluidFilm, NH Oil Undercoating, and Beacon Lubricants Signal 150 are a few popular ones. Spraying used motor oil was an old method but these newer products are superior in terms of longevity and coverage.

If you have rust already, remove as much as you can, then treat the are with Ospho to chemically stop the rust before treating with a coating.

Tundrawolf

Well, the van is probably never going to be in a heavy salt area in the winter for very long. In fact I tend to avoid those areas, because I hate the cold/snow.

Realistically, the van is going to spend most of its time in warmer climates with no salt. I may drive "through" them, maybe, but rarely.

Realistically, the frame is literally bare, and I just want to treat it with something before I put the van top back on it, and fit the covered utility bed, but I don't want to rattle can it and it not be effective.

I remember reading about a test that was done, they had taken some dock cranes used for loading shipping containers, and they took them down to bare metal.

now, at the docks, they are directly over the ocean, and rust is MAJOR.

They used a regular primer on some, and a high zinc primer on the others.

Then, they painted the regular primer cranes(s).

They discovered, while the zinc primered cranes showed virtually no rust EVEN WITHOUT PAINT, the regular primered ones, even WITH paint, showed a lot of rust damage.

So, I will be using a zinc rich primer. I am still at Mastercoat- which is a zinc rich formula, and honestly, if it can withstand salt areas (better than POR 15 by a factor of 14) on a bridge of all things, which is subjected to the same rocks, dirt, sand, salt, and debris that the underside of my van will EVER see, i think it is a good solution!


my only other question is, I read that spraying paint on wastes 30 percent of it, but rolling it on is better. I am not concerned with time it takes, but with wasting expensive paint/primer. I may roll it on, after thinning it. I can probably do the frame in just a few hours, if that.

Tundrawolf

There is a problem.

I am now limited to either local primers or maybe getting something off of the net- because the company that makes Mastercoat- is basically out of business, and you can no longer get the product.

I tried emailing them, but it is rejecting my email, similar to the mailer daemon.

On their website (Cannot find their products on ebay, amazon.) they say, in some cases, they won't have more product until 2018! It is 2024 now. In another product, they say they will have more in March of 2025!

So, this is an issue.

Any other zinc rich primer recommendations?

Right now, I am back to cold galvanizing compound, and then a standard undercoating, a hard, then soft undercoating.

Thanks

VanKo

This doesn't just apply to salt. Even if you live in a no-salt area, sand and road debris can still pierce the encapsulating coating. This allows moisture to get into the shell and stay there. An oil or zinc based paint can be a good option, I just wouldn't use any product that creates a shell around the steel - it defeats the purpose of protecting the steel.

Tundrawolf

I see the wisdom in what you are saying.

However, the factory "coating" on the frame- is abysmal. It is spottily applied, thin where it is applied- and straight up does not even exist past the drivers side door (Bare steel.)

I also bought a donor frame, a 96 K2500 for parts from it, and that frame has absolutely no coating on it whatsoever.

From my perspective, any coating is better than what's on there now: which is essentially: Nothing

I see the logic in repeatedly applying a, oily protectant such as used motor oil, yearly to it.

However, if I have to work on it, the last thing I want is to be working with oil covering everything.

I may be under it frequently, inspecting it, as it will be lifted, 4x4, and have tons of storage underneath. I may be table to monitor the frame and touch it up.

I also discovered, that the number one area for rust is actually the top of the frame. That will get the most coating, and will not be subjected to the same debris as the bottom rails.

Still looking for a decent cost effective solution.

Tundrawolf

Alos, could the mobile version of this website possibly cram any more ads down your throat? It's like something out of a dystopian comedy.

Ironic they probably don't use ads to sell anything, but to torture you into giving them money to make them go away.

Late stage capitalism seems to be run like something out of a horror comedy.

Triaged

YouTube dude has done tests and shows other products that also work well. Project farm has done some too. You could also just do a black wool wax or fluid film.