VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 POR for under body surface rust??

The underside of my floorboards (31 coach) are solid, but have a lot of surface rust and are what I might call a bit scaly. Would anyone recommend for or against using POR15 to seal this area to that any further rust would be stopped?

I won't allow POR 15 in my shop.

Why?

POR-15 will work well for that application. Wire brush off the scaly rust. You can brush paint on the paint. It is self-leveling as long as the weather is not too hot and humid. Just be aware that if it gets on anything not intended to remove quickly. I use a rag or paper towel with a little lacquer thinner. Also clean the brush with thinner as well. I have used POR-15 for many years with nearly 100% success. Be aware that it is not UV stable so if in a place to see a lot of sunshine it should be top coated. If in a protected area it dulls a bit over time but still good coating. Takes dynamite to remove once cured.

Some of the details listed in Chipper's description above explains why.

I have used POR-15 very successfully on early '60 Chevrolet restorations on the undersides of the bodies.

I brush POR-15 on the undersides and then spray top coat it with red oxide primer within the 72 hour window for the POR-15. Many of the early '60's cars came with the underside only with red oxide primer on them. With the POR-15 / red oxide primer combination the undersides look "original" and the finish holds for a very long time.

That will be a unpleasant job to brush any product under there, with all the obstacles. It will be difficult to reach every area.

At my age, and if I did not want to pull the body off, I would use some sort of sprayer with a short wand, and use thinned oil. Oils will weep into spotwelded seams and nooks you can't see.

That was a common thing done at gas stations 50-60 years ago, to stop the salt damage. They would spray it, and tell you to drive 10 miles on a dusty dirt road to form a coating that would stick for a few years. LOL

I really don't see anything in Chip's post as to why "it's banned from you shop"
I was hoping you were going to give me specific reason other then a general statement. The instructions on the can say the same things as Chip said. I never heard anyone ever complain about it other then you. I use it after I am done welding not before, little tricks like that will make your day easier
1)Don't use it in direct UV
2)DO NOT get it on your skin
3)DO have the por 15 solvent handy

I too, like Chip have used it for many years. It is pretty much 'forever' Remember you are not getting it off the surface unless you grind it off, for rust encapsulation it's great. For removal on your skin have the solvent, and I would not use it unless I had the solvent right next to me. Also PPE is a must, I would not want it splashing in my eye's

This is why I posted about the difficulty of trying to brush it on with the car not disassembled. There are so many things in the way under there, to do a good job without getting it all over your skin and eyes.

Frank, you are right! it's all part of the prep work. I use a paper suit with a face mask and hood, and I wear full eye protection. I tried everything to remove it but the solvent is the secret potion to have on hand.
You are right the red oxide is pretty much a dead match for the belly of the car. I wish they had that color years ago

There was lengthy discussions about this product some years back, not all positive...I did use it with great success. I did do a lot of prep!!!using the recommended POR prep products as well as sanding, cleaning ,masking and taping

Don't forget the surgical or rubber gloves. I don't generally use them as I am careful and have the solvent and paper towel handy.

Remember to tape off or cover anything you don't want it to coat. It flows relatively well and slow cure so it will penetrate cracks and crevices with the help of gravity or a teensey puff of air.

When I did the frame-off on my 83' Chevy Blazer I used POR on all the underside surfaces. I had the body on the rotisserie and after a total sand blasting, was able to spray and flow it into all the nooks and crannies. After it dried, all the seams were seam sealed. POR does require a roughened surface to adhere properly. When I went to do the job, even the shop selling it told me I would need the special primer as it wouldn't adhere or do a good job on the "just the sandblasted" surface. A quick call to POR's customer service cleared that up and the bottom of my Blazer still looks like I just painted it 3yrs later.

John: If it is really that important as to why I won't use POR 15, then refer to some of the comments listed in the above posts, including a few of your own comments as well:

1. "It is not UV stable".
2. "It dulls".
3. "It takes dynamite to remove once cured".
4. "Don't get it on your skin".
5. "Remember you are not getting it off the surface unless you grind it off".
6. "I would not want it splashing in my eyes"
7. "I tried everything to remove it"

The above are few reasons why I won't use the stuff because I like other products better for the work that I do for my customers. However, the main reason that I won't use POR 15 is that it cannot be removed easily unless you grind it off.

I do a lot of restoration work on distributors, starters and generators. Many times I have had the above items come into my shop for a restoration by a customer that had his starter or generator previously coated with POR 15. It takes me forever to get that stuff off down to bare metal so that a show quality restoration can be performed on the item. Removing that stuff is very time consuming, and it costs the customer extra labor for me to do so.

As far as rust encapsulation goes, I don't encapsulate rust, I remove it!!! And the finish products that I use for top coats do not require as many safe guards as does POR 15 and they are not as messy. Also, if the next dude down the road has to remove the top coats that I use they can be removed with very little work, unlike the POR 15.

I have friends who are professionals in the car hobby that do very high quality restoration work and several of them won't use POR 15 either for the same reasons, so I'm not the only one that won't use the stuff as you stated.

You obviously like POR 15.... great!! However, there are probably some other products that you don't like for various reasons. That is your choice and your preference.

I don't like POR 15 for the reasons stated above and I won't allow it in my shop. That is my choice and my preference.

The only reason I asked you "why" because I wanted to know if you had a bad experience that I have not had yet, or experienced a problem recently that nobody was aware of. I only just asked for an explanation to see if I could gain some new knowledge on the product. I already knew not to use it on components, especially electrical, but I am sure many people don't know that and it is good thing you mentioned it to prevent people from making that mistake.

By the way thanks for editing your original post.