Chassis rust advice

Discussion in 'Amp Tech Center' started by jsnwhite619, Nov 19, 2019.

  1. jsnwhite619

    jsnwhite619 Friend of Leo's

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    I started a 6g3 for myself last year and between life, moving, and everything else, I still haven't finished it. Unfortunately, it was summertime in Georgia when I started it, and there's lots of fine rust - no pitting - where I touched it. The board isn't soldered in yet. The heater wiring is done though. Any tips on cleaning and preventing it from returning in those spots?
     
  2. Bill Moore

    Bill Moore Tele-Afflicted

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    I tried some CLR on some chassis straps, and it does remove the fine stuff!
     
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  3. Peegoo

    Peegoo Tele-Holic

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    Squirt some Deoxit on a cloth and scrub the stuff off.
     
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  4. Axis29

    Axis29 Poster Extraordinaire Ad Free Member

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    After cleaning (I might even try WD-40), throw some good paste wax on it. That'll help keep the rust away down the road.
     
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  5. Milspec

    Milspec Friend of Leo's

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    If there is rust on metal, there is a loss of metal and it will continue to rust unless you coat it. Cleaning off the rust is just part of the job, you really need to coat it to prevent it from rusting further. Wax probably will not survive the heat for very long in operation, so that may not work. Maybe a brush on paint (aluminum color) would do the trick once cleaned off or even a metal polish that leaves a coating behind like Auto-sol?
     
  6. rangercaster

    rangercaster Poster Extraordinaire

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    Rust never sleeps ...
     
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  7. jman72

    jman72 Tele-Afflicted

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    I made the chassis for my 5e3 out of sheet metal steel about 6 years ago. I spray painted it with silver Krylon, and it worked great. It hasn't rusted yet and looks pretty good to me. Not a great pic angle, but you can generally see how it looks. I'm in the process of building another amp and I'll do the same thing for the new one.

    amp_3.jpg
     
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  8. peteb

    peteb Friend of Leo's

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  9. jsnwhite619

    jsnwhite619 Friend of Leo's

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    Thanks for the suggestions everyone. I found an old bottle of Naval Jelly that was my father-in-law's but the dang plastic bottle cracked & busted when I tried to open it. Couldn't have been more than 25-30 years old!

    Like I said above, luckily, the heater wiring is the only thing in there right now that just can't be removed and dealt with easily. And there's no way I'm messing with it - I hate doing it too much!

    I have some stuff that came with a gun bluing kit that is for rust. Honestly, for everything on the outside of the chassis, I may wipe it down with boiled linseed oil and let it cure once it's cleaned up. Obviously, I use it on my cabinets, but the stuff comes in handy in lots of other ways. The can even has a section about using it to coat tools to prevent rust. I used it on that amp I built several years ago with the gun blued chassis. Heated the chassis on a gas cooker & wiped it down with BLO a few times. Like a cast iron pan.

    IMG_1074 (2).JPG
     
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  10. Chunkocaster

    Chunkocaster Poster Extraordinaire

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    For internal rust why not use a rust converter? Basically a vinegar based product that converts rust and prevents it from returning. The stuff they use on cars, trailers etc.
    You can buy it in liquid form to brush on if aerosol isn't suitable.

    [​IMG]
     
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  11. schmee

    schmee Poster Extraordinaire

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    I would avoid anything with acid in it, like naval Jelly, CSR (?) etc. My experience is they clean good but make the metal even more prone to corrosion afterwards. So I would use them on a bad case but for a light surface rust early on , I would not.
    It makes sense because acid attacks the grain boundary's in the metal, literally eating away at the edges of the "valleys", leaving them ready for further attack. You dont need to go that deep.
     
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  12. King Fan

    King Fan Friend of Leo's

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    Move to Utah. Typical humidity is 15-20%. Your hair is dry 5 minutes after your shower; your towel takes 10. Tweed disease is impossible, and indoor rust is an oxymoron.

    OTOH, you will have nosebleeds daily for several years, your hangnails will get fractal, your acoustic guitar will curl up like a potato chip, and your beer will either get a lot weaker or a lot more expensive.

    You choose. :)
     
  13. Axis29

    Axis29 Poster Extraordinaire Ad Free Member

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    LOL - I moved to SoCal, the desert actually, a year ago. I'm so happy that I can leave tools laying around in the shop and not worry about them anymore... Let alone my vintage amp's chassis.

    I've left my good acoustic in it's case for months now... I am afraid of leaving it out on a stand.



    Oh, and to respond to @Milspec, I've never had a problem with wax and heat on things like cars, tools, etc. I used it on my Twin and I've never had a problem with it, either. I use it in the workshop all the time. But, for things like the table saw and bandsaw's cast iron tables, I use Boeshield products. I picked up the three pack a few months ago (again) that includes a pitch remover, a rust remover, and their T-9 surface protectant. I haven't needed to do anything to my Twin since waxing it when I rebuilt it.

    https://www.amazon.com/dp/B001DSY55Y/?tag=tdpri-20
     
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  14. peteb

    peteb Friend of Leo's

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    interesting perspective and I agree with most if not all.


    first off, I agree that surface rust is much different than rust with pits and that you could probably sand or wire brush it off, but what will you do to keep is from returning? probably need to finish is some how.



    second, acid treatments are not finishes. As you say they will leave the metal vulnerable to rust. acid anodizing is a treatment industrial manufacturers use just prior to applying finish.
     
    Last edited: Nov 22, 2019
  15. peteb

    peteb Friend of Leo's

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    I had to check up on some of the details.


    Aluminum aircraft parts are acid annodized. The bath or solution is phosphoric acid and anodizing is the connecting of electrodes to pass electrical current thru the part. This is also how chrome is applied, and there is a coating.


    The auto manufacturers have a process before they paint the metal (steel) involving zinc phosphate, with the main component being phosphoric acid.

    Phosphoric acid is greenish and it is the main component in the rust mort product that I mentioned above.




    If the auto and the the aircraft industries rely on phosphoric acid in their finishing processes I don’t see any reason to avoid these acid based products. Their main use is to prep metals to accept a finish, not rust removal but in the end it is one and the same.
     
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  16. Milspec

    Milspec Friend of Leo's

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    Those acid treatments are to etch the metal so that the applied finish has something to bite into. Eastwood sold a very good product that would etch the metal and leave a white coating behind...perfect for painting, but not a durable finish left bare. I have no experience using that rust converter you picutured, but just throwing out what I ran across over the years.
     
  17. Milspec

    Milspec Friend of Leo's

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    Good to hear that it has worked on your Twin. I was just speculating since amps do get pretty toasty inside. With tubes running well over 300 degrees at times and carnuba melting at approx. 180 degrees, I was just worried that the chassis would get too hot for long-term wax survivability. I have never measured the actual temperature inside the chassis of a tube amp, but have been burned by one in the past so it had to be over at least 120 degrees on the metal plate.

    Again, just tossing out my concerns, but good to hear you have had success with it.
     
  18. Axis29

    Axis29 Poster Extraordinaire Ad Free Member

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    Your thoughts are perfectly logical and reasonable. My experience is a tiny spec of anecdotal evidence. Chances are you're probably closer to the truth, my friend! LOL
     
  19. Milspec

    Milspec Friend of Leo's

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    I doubt it, I tend to over-analyze things to death (my biggest flaw), but if it has been working well in real life then that is the reality.
     
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