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Rust - how to deal with it? scrape out, treat, prime, paint?

Discussion in 'Bodywork' started by rossyl, Oct 27, 2009.

  1. rossyl

    rossyl Hardcore MB Enthusiast

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    Hi,

    I'm going to do some rust repair on my car. I had a previous thread on here that didn't get much response, which is odd considering MB's rust!

    The Process

    From my reading the majority suggest a process such as:

    1. scratch out/grind out rust using a dremel or similar
    2. treat with some form of rust converter/remover
    3. treat with a zinc primer
    4. paint
    My question is what products are best for 2 and 3.

    For point 2:
    Jenolite I've heard good and bad things. Some suggest just buying phosphoric acid as that's all that jenolite is, haven't been able to find a supplier but that might be the best bet.

    Point 3 - I haven't seen any suggestions for the primer to use. Anyone recommend?

    One thing I have found is that hamemrite is not recommended.

    Cheers,
    Ross
    I haven't found a decent reasonably priced zince primer.
     
    Last edited: Oct 27, 2009
  2. bennesspipers

    bennesspipers Hardcore MB Enthusiast

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    I agree about hammerite,not worth the money, but im surprised to hear bad things about jenolite, what bad things exactly ? iv used it for years.
     
  3. lynall

    lynall Hardcore MB Enthusiast

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    When you have done it cover the underneath with ankor wax much better than waxoyl really sticks.



    Lynall
     
  4. Sorry Pete

    Sorry Pete Hardcore MB Enthusiast

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    A long time ago, Practical Classics ran their in-house test of a range of rust-inhibitors. I wish I still had a copy as their test was exhaustive and Hammerite came low on the list - in the range of 'it's better than no protection'.

    I can't remember which came top; I think POR-15 did well, as well as a Bilt Hamber product. If anyone remembers this article, I'd love to know which product came top. I've searched google for ages to find it. As with many things, the most expensive product was not the best.
     
  5. OP
    OP
    rossyl

    rossyl Hardcore MB Enthusiast

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    Cheers. This is for stone chips and surface rust.

    Just overpriced for what it is.
     
  6. Roger Jones

    Roger Jones Hardcore MB Enthusiast

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    Perhaps Hammerite's effectiveness varies depending on what it is applied to. I used it on the barely painted frame of a cheap Chinese-made garden seat a decade ago, doing nothing more than rubbing the frame with wire wool first, then cleaning it. It's still fine and has been outdoors all the time.
     
  7. IanT

    IanT Hardcore MB Enthusiast

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    I don't have a bad word to say about Jenolite, or for that matter, the green 'rust remover gel' that Halfords sell. Both though, are pretty weak in concentration and so you can get better chemicals if you try quite hard.

    I've read about a company called SPL who do dipping of any steel item from components to whole shells in hydrochloric acid and then started to look into whether it was practical to get the acid yourself for careful home use. Speaking to a colleague at work, he has done exactly that and brought me in a pair of small bottles with samples of hydrochloric acid, and phosphoric. That's noticeably stronger (quicker) and so it's easier to use, as it gets down into the pitting much quicker. Jenolite would take many hours of application, rubbing off, washing and re-application to get to the bottom of the rust.

    I think the steps you've got up there are fine, but be prepared to spend a good amount of time replacing the Jenolite and keeping it damp to help it to do it's work thoroughly. I normally use a small artist's paint brush with the bristles cut down to scrub the Jenolite into the rusty areas and keep clearing removed material. Then, once I'm finished with that stage, I wash it down thoroughly, dry it even more thoroughly (get it hot) and then use an etch primer to coat the clean metal before painting.

    As for Hammerite, the only observation I'd make is that it's great while it's new, as it's slightly rubbery and resists chips well, but leave it for a couple of months and then it's very prone to chipping and easily shatters when subjected to sharp impacts. Corrofast is cheaper and seems to retain some of that elasticity for longer.

    Ian.
     
  8. OP
    OP
    rossyl

    rossyl Hardcore MB Enthusiast

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    I've decided on the following

    - Dremel out rust
    - "Ph Down" to remove rust particles (instead of Jenolite, PH down is £10 a litre and is 80% phosphoric acid - use goggles and gloves!)
    - Bonda Rust Primer with Zinc (heard good things on canal boat forums :) )
    - Halfords Mercedes Brilliant silver paint sprayed into a can, then applied using a thin artists paint brush.
    - then top cost with halfords own.

    I've decided on the steps...now all i need to do is find the time!
     
  9. IanT

    IanT Hardcore MB Enthusiast

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    All I'd say about doing the dremel treatment is that you'll be removing good metal and thinning the panel. If it's really practical to grind down to the base of the rust then fine, but otherwise I think I'd go for a chemical attack and the extra patience.

    On the paint front, I painted my (now) spare W210 Avantgarde alloys with Halfords Brilliant Silver (allegedly the MB colour) from their rack, but it's neither a good colour or 'metallic texture' match so I'd have some reservations about using it anywhere visible. Also if it is visible, I think it's important that it is sprayed, in order to place the metallic particles onto the panel consistently, although that's personal experience rather than known fact.

    Ian.
     
    Last edited: Oct 29, 2009
    1 person likes this.
  10. OP
    OP
    rossyl

    rossyl Hardcore MB Enthusiast

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    I was only thinking of using the dremel on the wheeler arches, but might get away with screwdriver, 80 grit sandpaper then 1200 wet and dry. Elsewhere I'll use a screwdriver/stanley knife.
    Everywhere I'll use patience with the Ph Down.

    As for the Halfords paint, I'm keen to use it comes in a spray can. I can spray into the cap and then use it with an artists brush. With it already having thinners, i think the consistency will be easier to work with. However, I'll be sure to use it an out of sight area first to test. Whatecver the outcome, i'm sure it will look better than the orange rust!
     
  11. IanT

    IanT Hardcore MB Enthusiast

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    Completely agree, orange rust be gone!

    The main thing I'd suggest once you have got all of the rust out, is to make sure that you use sufficient primer and filler needed to get a smooth base for the colour to go on. It's even more visible on metallics when the prep isn't as perfect as it could be, plus depending on your view of why Mercedes-Benz had a rust problem at all, where sharp edges remain, the paint can be extremely thin and porous, allowing moisture and air in, starting the process all over again.

    Please do show us some photos when you do it, I'd be interested to see.

    Ian.
     

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