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  #1  
Old 01-31-2021, 11:32 AM
metaldahlberg88 metaldahlberg88 is offline
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Default Pitting Limits

I just got a couple fenders back from chemical strip and rust removal. The result is that there are a lot of inclusions left in the surface. There are several areas with pin holes which I know need to be replaced. I will also assume that areas with inclusions will need to be replaced. My questions is whether the pitting that does not have inclusions is safe to keep? I would assume the rust removal was effective in those areas and it is good to go from that perspective.

Inclusions









Pitting without inclusions


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Old 02-02-2021, 01:54 AM
crystallographic crystallographic is offline
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Originally Posted by metaldahlberg88 View Post
I just got a couple fenders back from chemical strip and rust removal. The result is that there are a lot of inclusions left in the surface. There are several areas with pin holes which I know need to be replaced. I will also assume that areas with inclusions will need to be replaced. My questions is whether the pitting that does not have inclusions is safe to keep? I would assume the rust removal was effective in those areas and it is good to go from that perspective.

Inclusions









Pitting without inclusions



Hi Tommy,
I'd pick out those inclusions with a sharp point, straighten the panels and get them fit up. Then I would take a look at what can be welded up a touch at a time and hammered out hot, and what needs a little round or oval patch cut and welded in.
If a thin spot is not affecting strength, then let it go. If you see daylight then weld it up.
Clean, clean and clean is the best rule for metal work.



Phosphoric rinsing is the best to prevent re-rusting, as previously-rusted areas always rust up again more quickly - just watch the humidity go after freshly cleaned old fenders in 2 weeks' time .... starting right in the rust areas, first.
A 25% phosphoric wash corrects/neutralizes the oxidation potential established by the rusting....and also welding does, too.


Good luck!
(ps, I've done a lot of rust repairs on old cars.)
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Last edited by crystallographic; 02-02-2021 at 10:13 AM.
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Old 02-03-2021, 10:53 AM
metaldahlberg88 metaldahlberg88 is offline
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Originally Posted by crystallographic View Post
Hi Tommy,
I'd pick out those inclusions with a sharp point, straighten the panels and get them fit up. Then I would take a look at what can be welded up a touch at a time and hammered out hot, and what needs a little round or oval patch cut and welded in.
If a thin spot is not affecting strength, then let it go. If you see daylight then weld it up.
Clean, clean and clean is the best rule for metal work.



Phosphoric rinsing is the best to prevent re-rusting, as previously-rusted areas always rust up again more quickly - just watch the humidity go after freshly cleaned old fenders in 2 weeks' time .... starting right in the rust areas, first.
A 25% phosphoric wash corrects/neutralizes the oxidation potential established by the rusting....and also welding does, too.


Good luck!
(ps, I've done a lot of rust repairs on old cars.)



Thanks Kent. I really appreciate the advice.



Per your suggestion I was able to make a bit of progress. Tedious process though. Took me almost an hour to clean out just this little section. I'll just keep plugging away at it.








This section is heavy though; more like a big caked on section than spots. It's not discrete spots I can pick at. So maybe I can sand it a bit, let it soak in naval jelly, scrape, repeat? We'll see....









Unfortunately (for rust prevention purposes) these are the first pieces of the car I am restoring so I will probably have to periodically hit it with the phosphoric acid wash until I am ready to get the car into paint which is likely quite a ways away. My plan is to use diluted Klean Strip Concrete and Metal Prep which is 35-45% phosphoric acid to arrest any humidity rust that may arise. Luckily AZ is nice and dry most of the time so hopefully it won't have to be done too often.
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Old 02-03-2021, 11:29 AM
crystallographic crystallographic is offline
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Originally Posted by metaldahlberg88 View Post
Thanks Kent. I really appreciate the advice.



Per your suggestion I was able to make a bit of progress. Tedious process though. Took me almost an hour to clean out just this little section. I'll just keep plugging away at it.








This section is heavy though; more like a big caked on section than spots. It's not discrete spots I can pick at. So maybe I can sand it a bit, let it soak in naval jelly, scrape, repeat? We'll see....









Unfortunately (for rust prevention purposes) these are the first pieces of the car I am restoring so I will probably have to periodically hit it with the phosphoric acid wash until I am ready to get the car into paint which is likely quite a ways away. My plan is to use diluted Klean Strip Concrete and Metal Prep which is 35-45% phosphoric acid to arrest any humidity rust that may arise. Luckily AZ is nice and dry most of the time so hopefully it won't have to be done too often.

You are doing well - and learning this process.
Pool cleaner is muriatic ...smokes when applied with NASTY unhealthful fumes ... but I have cleaned aircraft military drop tanks enough to save them to usefulness - outdoors, over open ground, with air supply - and added 5lbs of (costco) baking soda over the wet ground after, neutralizing the acid, then a water sprinkle rinse over that. Weeds came right up a week later.


Another thing - using slapper and dolly to smooth our the rusty panels sure helps knock loose the inclusions! (hint)


Use a bit of a tap with a 6oz ball pein onto the pick/point to help persuade the inclusions free.


AZ has great restoration weather!
Yeehaw!
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Old 02-03-2021, 04:11 PM
norson norson is offline
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[QUOTE=crystallographic;167074]You are doing well - and learning this process.
Pool cleaner is muriatic ...smokes when applied with NASTY unhealthful fumes ... but I have cleaned aircraft military drop tanks enough to save them to usefulness - outdoors, over open ground, with air supply - and added 5lbs of (costco) baking soda over the wet ground after, neutralizing the acid, then a water sprinkle rinse over that. Weeds came right up a week later.



Thanks... I wash the citric acid off my parts after removing from my tank on my backyard grass and the grass suffers. I'm going to now use the baking soda. Again, thanks. (Didn't have this problem with molasses).
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Old 02-03-2021, 08:15 PM
metaldahlberg88 metaldahlberg88 is offline
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Quote:
Originally Posted by crystallographic View Post
You are doing well - and learning this process.
Pool cleaner is muriatic ...smokes when applied with NASTY unhealthful fumes ... but I have cleaned aircraft military drop tanks enough to save them to usefulness - outdoors, over open ground, with air supply - and added 5lbs of (costco) baking soda over the wet ground after, neutralizing the acid, then a water sprinkle rinse over that. Weeds came right up a week later.


Another thing - using slapper and dolly to smooth our the rusty panels sure helps knock loose the inclusions! (hint)


Use a bit of a tap with a 6oz ball pein onto the pick/point to help persuade the inclusions free.


AZ has great restoration weather!
Yeehaw!

Muriatic really did the trick. Amazing results in about 1.5 hours of work. Probably got about 90% of the inclusions out. Still some big ones stuck to some of the flanges on the fender. But wow, what a result!







I will keep the other tips in mind as I work through the rest of the car. No doubt I'll be using a variety of those techniques. Thanks Kent!!
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Old 02-03-2021, 09:29 PM
BTromblay BTromblay is offline
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Hi,

While reading this post, it brought back a memory from 25 years ago. My best friend that I grew up with had gotten married and moved into a nice little house in town. He had invited me over so that we could try out and play with his new portable sand blaster with a 7hp Ingersoll Rand air compressor. Why use sand, when at the time the new product on the market was baking soda for paint removal. I had the aluminum cowl piece for my Stinson L-5 and it worked great. Took the paint off, no distortion, easy clean up with a light coat of white powder backing soda all over his drive way and fine manicured green, lush, lawn....

Several days later, phone rings... Hey whats up?? "YOU KILLED MY GRASS" !!!!

Best we can tell was, we changed the PH level of the lawn and killed it dead for most of the summer. I thought it was funny, but I didn't have to live with Brians wife
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Old 02-04-2021, 03:50 AM
norson norson is offline
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Careful of the Music acid. I've heard stories of an open container of it causing tools and other bare metal stuff to develop serious rust. I wouldn't have it in my shop.
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Old 02-04-2021, 06:59 AM
crystallographic crystallographic is offline
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Careful of the Music acid. I've heard stories of an open container of it causing tools and other bare metal stuff to develop serious rust. I wouldn't have it in my shop.

Hi Norm,
We buy it when we have a job for it. Then we use it on the job. Then we clean it all up. Some stuff is best fresh - not kept around so long it leaks and gets messy. Not all shop supplies are meant to be stocked long-term.
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Old 02-04-2021, 07:21 AM
metaldahlberg88 metaldahlberg88 is offline
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Everyone in my neighborhood has rocks for a front yard. No grass to kill!! Did the baking soda trick anyway. Hopefully I won't have the acid in the shop for long. Nasty nasty
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