Overland Defender Chassis HDG Vs. Zinga Vs. External Coating

  1. Wheely

    Wheely Member

    Messages:
    26
    Location:
    Accra- Ghana
    Hi guys,

    I am stripping down my Defender to prep it for my Africa Overland.

    I am down to 3 options:

    -Hot-Dip Galvanising
    -Zinga (Cold Galvanising method): Zinga is an active zinc performance coating which works in conjunction with the metal beneath whereas paints are only passive barriers. Regardless of how thick paints are applied, they remain as barriers. Once they are breached corrosion sets in immediately. If the Zinga layer is sufficiently damaged to expose the base metal below, the steel would form a layer of surface rust but no corrosion would take place beneath it.
    -External Coating paint Epoxy Mastic 121: (winner of the Winner of the Classics monthly 3 year test http://www.rust.co.uk/filestore/3 YEAR TEST SUMMARY PDF.pdf) Epoxy Mastic is a two component Epoxy paint composed of nanoscale corrosion protective pigments in short chain molecules with very low surface tension. This allows the paint to flow into all of the pits and troughs on the steel's surface, ensuring a tough penetrating primary bond. This is the best kind of bond you can get with a paint finish.The high build epoxy forms a super strong protective barrier over the corrosion inhibiting pigments that hug the steels surface Excellent penetration and adhesion within a high build coating equals exceptional mechanical strength.

    What are the pro's and con's of each of the 3 alternatives? what would you guys choose and why?

    Thanks,
    Simone
     
  2. fizzy Forum Supporter

    Messages:
    4,713
    uk
    Hot dip is the best of all but expensive.
    I have used various epoxy paints - the best value seems to be jotun epoxy aluminium jotamastic 87AL - the aluminium gives added corrosion protection.

    https://www.smlmarinepaints.co.uk/primers

    Epoxy ideally needs a sand blasted finish - it can be brush applied.

    I have no experience of Zinga.
     
  3. atomant48

    atomant48 Member

    Messages:
    744
    Salisbury UK
    Time a factor?

    Hot dip (presumably) gets someone else to do all the work. Depending how you're doing it epoxy Mastic would be you doing the prep and the painting. I'm not a fan of a galv finish - but then the epoxy is not to everyone's taste either. What final finish are you after?

    The epoxy can take days to cure before you carry on with the build. I'm guessing the hot dip is ready to go once you get it back.
     
  4. CompoSimmonite Member

    Messages:
    4,209
    Location:
    Werrington, Stoke-on-Trent
    Hot dip will acid clean internal cavities as well as outside and then coat internals with galv so no contest IMO.
     
  5. Rannsachair

    Rannsachair Forum Supporter

    Messages:
    1,090
    Location:
    Lochgilphead, Argyll, Scotland
    I would go hot dip galvanised too. If f your chassis is good, it is a lot cheaper than a new galvanised chassis., I unfortunately found my 2002 chassis was not as good as I thought and came back from the galvanisers with pin holes where the rear crossmember attaches, the rest was perfect. In the end was good to find the faults and O ended up buying a new chassis.
     
  6. rcx132

    rcx132 Philip

    Messages:
    1,842
    Location:
    London, UK
    I always go for the epoxy primer because I don't want to risk warping my chassis. Dunno about Land Rover's but I've measured Jap chassis' and they are straight to within a few mm, even small warpage could potentially cause handling issues.

    With hot dip you would ideally also get your chassis professionally cleaned by acid/caustic dip or similar methods, so that the zinc can properly adhere to the inside of the chassis. Others on here will tell you it doesn't matter, but no textbook, manufacturer, or commercial manual will confirm that, they all say the metal needs to be cleaned. The hot dip factory will do some cleaning before the dip but in most cases the cleaning they do is only designed as a final stage. Last time I was at the plant they said their process will remove smutting and light rust but not paint or embedded rust and that's using a five stage cleaning process.

    The epoxy takes time to apply if doing it by brush. I'm going to spray my next chassis, it just means you need some method of hanging it so your spray gun is horizontal when applying.

    The epoxy 121 is just overpriced rebranded Jotun, and not even the best Jotun product.

    If using epoxy, if you care about the car, I would also top coat it as most epoxy's are not designed to be exposed to UV or chemicals, that's what the top coat is for.
     
  7. CompoSimmonite Member

    Messages:
    4,209
    Location:
    Werrington, Stoke-on-Trent

    Land Rover chassis are never very straight, even brand new from factory, and measurements are + or - a certain figure so no worry about distortion from hot galv.
     
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  8. rcx132

    rcx132 Philip

    Messages:
    1,842
    Location:
    London, UK
    Well there you go, maybe Land Rovers are more suitable for hot dip. I've only glimpsed at Land Rover chassis' but they do seem much beefier than Jap/German 4x4's.
     
    CompoSimmonite likes this.
  9. steveo3002 Member

    Messages:
    5,054
    cambridge uk
    epoxy mastic 121 is much the same /some say re labeled jotun jotamastic thats much cheaper if the price helps you decide

    ive been pretty happy with it on cleaned up steel...only bits to come back are where ive been slack on the prep
     
  10. Pigeon_Droppings2 Member

    Messages:
    1,971
    Location:
    london
    I'm a big fan of epoxy...I've had good results once the steel is well brushed. I also like the fact that it's easily repaired if it gets damaged....haven't tried the other methods though so they may actually be better.

    Personally I prefer to roller my epoxy on with a mini foam roller...I find a brush just puts it on too thick for my liking.

    Hot galvanising sounds like the gold standard to be honest...but I'm restoring for enjoyment so I'd always opt for doing it myself even if it takes an age. Each to his or her own I guess...and if you are on a timescale maybe best to outsource the work.
     
  11. rcx132

    rcx132 Philip

    Messages:
    1,842
    Location:
    London, UK
    Not convinced that hot dip is better than epoxy. Hot dip is an active surface, it reacts with acid. Road spray is slightly acidic so the zinc slowly but surely burns off. Epoxy doesn't react that that, so if not damaged it lasts and lasts. Zinc does have other advantages though eg it gives anodic protection so the two are probably hard to compare.
     
  12. fizzy Forum Supporter

    Messages:
    4,713
    uk
    Get epoxy aluminium or epoxy zinc and you get the same advantages.
     
    Pigeon_Droppings2 likes this.
  13. CompoSimmonite Member

    Messages:
    4,209
    Location:
    Werrington, Stoke-on-Trent
    I never leave galv unpainted on chassis. Several coats of polyurethane paint over the galv is my method.
     
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  14. GW8IZR

    GW8IZR Gone.

    Messages:
    2,323
    Location:
    Anglesey
    Some of the local LR's have had galv chassis and sheep / cow excreta and slurry rips it off in no time, if you do have it galved I would definitely paint it as well, also a black chassis doesn't attract as much attention from the scum.
     
  15. darren.a.roberts Member

    Messages:
    113
    Cambridge
    Have you looked at any of the BuzzWeld products?
     
  16. clift_d

    clift_d Member

    Messages:
    462
    Location:
    Hackney innit (UK)
    HDG and paint / PPC.
     
  17. Wheely

    Wheely Member

    Messages:
    26
    Location:
    Accra- Ghana
    Thanks so much guys for your feedback! No one commented on the Zinga - is that such an unconventional product? According to their website it has most of the benefits of HDG (without the ability to galv the cavities though) but it doens't have the risk of wrapping.

    I was thinking of getting to the stake of applying Zinga which can be readily sourced in Ghana where I am, and apply on top the epoxy mastic (or the Jotun alternative) - thoughts?
     
  18. Sputter Forum Supporter

    Messages:
    50
    Location:
    Shropshire England
    I started using zinga on odd things that couldn't be readily galvanised about 10 years ago. If you haven't used it before Wheely, it's strange stuff that is worth trying at least once in a lifetime, just because it so different to anything else. I can remember the first time I dipped a brush in and thought how strange it was. Leave the brush out and it soon goes hard, then softens again when you next dip it in the zinga pot.
    It's great for restoring the rust proofing on non-cosmetic areas that have taken a bit of a ding, only thing to watch is that it likes clean metal - said to be best if bead blasted, although I've only ever used a fine grit paper.

    One good point for me was that unlike paint, it can be applied when the weather is cold, so you can protect bare metal and then paint it later when it's warmer - maybe that's not so much of a bonus in Ghana

    Zinga does protect for much longer if it is pained over. I have not tried it with epoxy paint, though looking at their website they says that's no problem, just wait 24 hours before painting.
     
  19. Wheely

    Wheely Member

    Messages:
    26
    Location:
    Accra- Ghana
    Great thanks!

    I finally found out that Jotun is available in Ghana! They have many types of epoxy paint - which one would you guys recommend for the chassis ?

    Thanks a lot!
     
  20. Dave109 New Member

    Messages:
    1
    Location:
    leeds, england
    The Jotun/Epoxy 1:1 argument settled, from the horses mouth:


    Hi Dave

    Thanks for contacting me Dave I am very happy for you cut and paste this reply for me and put this one to bed.

    Rustbuster can state without any reservation at all that our Epoxy EM 121 Epoxy Mastic or any of our other products are not manufactured by Jotun Paints.

    To clarify it is not the same as Jotun Smart pack or Jotun Jotamastic. The product is packaged and produced by Rustbuster Ltd at our Spalding facilities using Epoxy Resins formulated specifically for Rustbuster Ltd. We also supply in twelve colours, Jotun Smart Pack is not available in twelve colours. The hardener comp B is a totally different colour and viscosity to the Jotun product with faster curing times. Using the same thinners is common in the coatings industry paint manufacturers do not refine their own thinners. Even the largest paint manufacturers do not actually manufacture all of their paint lines. Epoxy Mastic is a generic term used in the coatings industry for a high build, high solids surface tolerant epoxy. So yes basically the poster is talking rubbish and maybe even liable. The products others are using are not the same as the product you have used to great success.

    Rustbuster also formulates all of its branded chemical products, our products are unique and packaged in small containers specifically for the DIY and restoration market, if any of the forum users want to purchase in large trade packs or bulk orders of any of our products I'd be happy to offer them a trade discount. Rustbuster are qualified rust prevention consultants and consultant engineers we have level 3 Icorr Corrosion inspection status, and are a member of Icorr, we manufacture to an independently audited Iso 9001 quality assured system. We also work with major vehicle manufacturers on this basis recently supplying a major UK based vehicle manufacturer with products and advice on our Rustbuster Weld-Thru primer for testing at their Weld and Corrosion testing facilities at Cranfield.

    When you buy a Rustbuster product you get the benefit of all of this experience with every tin, we personally answer all of our email enquiries. Something you probably won't get buying a marine paint off Ebay. We are a Micro manufacturer when compared to Jotun but we are small enough to care, you also keep British folk in employment.

    Glad you like the products Dave, all the best with the Mini restoration.

    Regards

    Ian Allen

    Managing Director

    Rustbuster Ltd
     
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