Technical Can I get away with POR-15ing this?

I've been doing a ton of metal work on the '54 and frankly, I'm just tired of it! This is at the bottom of my rear window. It's got some fairly deep pits although none of them are all the way through the metal. This area is completely covered by the window gasket and stainless trim and will not be seen. I'm wondering if I can grind most of the rust out of the pits with my die grinder, give it a coat of POR-15 and call it good. The car is gonna be a driver. Thoughts?

 

I've seen folks who have covered up worse with Por and other products, but have never seen what happens after years.

 

If done correctly (get rid of all the rust you can), it should be OK. I did the entire under side of my '51 in the winter of 1988 by sandblasting it and painting it with POR-15. It is still holding up well after the intervening 32 years. I think the reason it has lasted this long is that the car is only used in nice weather and stored under optimum conditions. Oh, I have gotten caught in the rain a time or two over the years, but all in all, times have been easy on the old girl. I should think that being in California would be even easier on the car than living in Minnesota, like mine does.

One thing I would do differently is to sandblast the areas rather than using a grinder. You will remove a lot more rust and a lot less metal. Suction blasters are cheap, and if you have a compressor, you can even rig up an outfit and blast out of a bucket of sand. Perhaps one of those little guns with their own supply of sand would work for this.

 

Small area. Not exposed after a repair.
Cut out and weld in a patch.
Easy work. Do it right after all you’ve done already.

 

I would sandblast it then neutralize the rust that remains in the pits.

 

This doesnt make sense. POR15 only sticks to rust. It doesnt stick to bare metal after its sandblasted

 

Manyolcars, I've sandblasted frames, and undercarriages of cars, and painted them with POR-15 and sometimes, it's Topcoat black. My Chevy has been dome for years, and no issues. I do not like using it on anything that gets good paint, like on the exterior of a car. Great on backsides of panels that have been welded.

 

This is how you seal /level heavy pitting and pinholes that sticks to clean steel and can be painted over with and the paint will stick

 

My experance I retired from running a grain elevator in Kansas. We had some steel tank storage it is hard not to get some moisture coming in at the stem wall. Wet grain and even galvanized metal are not a good combo. Result rust along the bottom 6 inches. We used NAPA version of por15 and it stood up well in the following years.

 

I don't believe in leaving rust in the pits. It WILL come back out. Sandblast it out, and paint as you would the rest of the body. Find a buddy with a sandblaster and you will be done with that area in five minutes. It will take longer to blow all the sand out of the nooks and crannies.

 

I would also prefer to sandblast it. At the lest wire wheel it and put a coat of ospho or other rust converter to get anything in the pits. Then prime and paint. I wouldn’t bother with por15 there.


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If you use an etching product , scrub all the rust out then prime & paint , in all likelihood it will outlive you , por 15 you're better off to, sandblast , grinding removes good metal , por15 will stick to most anything solid , even old paint again , it'll outlive you . My rearend housing , used a wire brush ,got all the rust ( within reason) cleaned it with lacquer thinner , POR15 then rustoleam enamel ,its been 21 years , no rust yet ...

 

Unless you go completely nuts, warping panels and removing LOTS of metal, there is always some rust left in the pits.

What I wouldn't do is try to "neutralize the rust" before applying the POR-15.

 

Get one of these for a small area like that. Less mess.
https://www.amazon.com/Neiko-30042A-Nozzles-Included-Sandblaster/dp/B000I8W7XW

 

Take a rubber ball or tennis ball , cut in half , cut hole so the nozzle just fits , makes a cheap spot blaster ..

 

Another little tip , if you use etch ( naval jelly etc.) to final dry after rinsing , use an old hair dryer to dry , not your air gun . Unless you're using air that's come through water traps , you're spraying that surface with moisture ..

 

as petejoe said with the work you have done and not being visible when done.use a zip wheel cut it out weld in new.rust never sleeps so kick it out.take a breath then commence the job you will rest easier after.another thing to consider is how thick does the pore need to be if too thick it will stand proud and I feel will not allow the trim to fit properly.if you need to sand (grind)it down what benefit will it have?as most times it is used there is no consideration for it needing (sanded ground).with welding in a piece if you do not get carried away it will need little grinding no need to fill (bondo) after as it will be hidden.the time you spend trying to blast or grind out the rust only to discover those blemishes are really paper thin and blow through anyway.do it once do it right

 

Ask me in a couple years, let you know how it goes
On my avatar, I have some serious surface rust and pitting in the rust on the roof of the cab, the metal is solid ... Everything else is coming along fine. Only the roof where it got the worst damage. 1000 times larger a area then you show and in a visible area, not covered.
I have tried everything that I can do, used acids muriatic, phosphoric, ospho ... rust is dead. I just cant remove it without sandblasting. A grinder with 36 grit paper and a hard plastic backing, just polishes the rust & not remove it. I have no means to sandblast it in place, no way to pull the cab and haul it somewhere to be blasted.
This issue has held up my project for months as I learn to work through it.

I decided with ospho as last acid on it, I am going to go to napa and get a rattle can of 2k sealer and seal it in. spray it with high build primer, put some icing on it and prime it again, sand it and eventually spray my tractor supply paint on it. See how long it last?
Thinking when it is running and driving, I can drive it to a company that can mask off the truck and just sandblast the roof. Or I may find a donor roof and cut it off and replace it.
I know I am coming back to this issue later. I have to regain momentum and move forward.

Excuse if I laugh with you and not at you. You probably could have either ground it out, or cut out and replaced that tiny little patch and done it right .... in less time then me writing this post. I feel your pain. Sometimes you just need to walk away and take a break. Come back with a clear mind. Suppose to be a hobby and fun.
I am doing what you are suggesting, cause I know I am out of options. And I know it is wrong.
You still have options, and just need a break from paint jail.

 

OK. After a good nights rest, I've come to my senses. I'm gonna cut it out and weld in a patch. Compared to the metal work I've been doing for the last few months on this beast.....this is a walk in the park!
Thanks everyone for the input!

 

You vented a bit, had some sympathy, and now you've made the right decision. Well done. I know how that feels!

 

To play devils advocate, can you treat the backside of the panel after it's welded in place. I wonder if using a spot blaster might be better ????

 

I don't see what the issue would be with just spot blasting that area. Provided the metal isn't so pocked that it's weak, you could get the rust out of the pits with a light blasting from a basic Harbor Freight gun and just a light coat of filler over. I think that would be a perfectly acceptable repair.

 

Glad you’re doing it correctly.
We all need a little hug now and then.

 

I am with petejoe totally sometimes you need to retrench realize that is a mole hill compared to what you have accomplished.I and I am sure many came to the same conclusion after walking away and relaxing and were very happy that they did.as the saying goes do it right or do ----I am looking toward your updates.

 

If you put filler over pinholes after you paint it you will have a bubble. I went through this on 40 coupe that had a pinhole in the panel that kept bubbling a day or two later. Turns at the was a big rust spot on the backside. Before you waste a lot of time and money get some Allmetal filler and fill it with that first. Do the backside to.If you can solder them that would be the better way to go.I hope this helps

 

POR 15 sticks to everything, fingers, shoes, clothing and anything you didn't mask off. Found some drips on my black steering wheel which I think will probably be there forever.

 

Anyone mention a spot blaster yet?

 

Call POR -15 and talk to tech about their primer they use over POR-15. Now leave some rust, coat with POR -15 and prime according to their directions. Paint.....

 

Cut out and replace? filler? POR-15 wont stick to...I remember when the HAMB was a source of tech not a bunch wild guesses.

 

Ding-Ding-Ding-Ding! That's what make that Por-15 successful ...paint it over the rust.
I vote to cut it out and make a patch....you've come too far to cut corners now!
6sally6