Undersealing/Rust treatment

  1. Saxperience Forum Bum Joined: Mar 2009 Stoke-on-trent Posts: 2640 Mk5 Golf GTTDI Mk2 VTR Project
    #1
    Ok before anyone jumps on me I know this has been asked a few times but I want to get a few opinions on what works best.

    Basically I want to underseal the whole car and take my time to do a proper job so that hopefully its not going to be crusty again a year later.

    I have previously painted the underside of the bootfloor with hammerite straight over rust paint ( I got rid of all of the crusty bits and smoothed it as much as possible first ) but it only took a couple of months for it to start creeping back through the paint and now after a year or two it just looks as bad as it did before and am doing the whole process again!

    What i'm asking is has anyone actually got a good method that has worked for them and kept the rust at bay for a good amount of time?

    I'd appreciate if anyone has any before and after photo's or even a photo of what your car looks like after a year or so of being undersealed.
  2. Frequent Poster Joined: Oct 2013 Bridgend, South Wales Posts: 948 Mk1 VTS, FF BG 182
    #2
    Jigs is the man to ask on this subject.
  3. Saxperience Forum Bum Joined: Mar 2009 Stoke-on-trent Posts: 2640 Mk5 Golf GTTDI Mk2 VTR Project
    #3
    Thanks Any other input welcome
  4. Saxperience Hardcore! Joined: Dec 2007 smurfland. Posts: 17346 Ex saxo owner.
    #4
    I've used red oxide on the underside of cars many times,after wire brushing off the loose rust.It lasts pretty well.
  5. Saxperience Forum Bum Joined: Mar 2009 Stoke-on-trent Posts: 2640 Mk5 Golf GTTDI Mk2 VTR Project
    #5
    Quote:
    Originally Posted by stevo67 View Post
    I've used red oxide on the underside of cars many times,after wire brushing off the loose rust.It lasts pretty well.
    Do you topcoat it with paint?
  6. Saxperience Hardcore! Joined: Dec 2007 smurfland. Posts: 17346 Ex saxo owner.
    #6
    No not always it's a personal preference,you can if you want to but not necessary mate.
  7. Newbie Joined: Feb 2015 Posts: 29
    #7
    I've found Hammerite/Smoothrite to be a waste of time, It's too hard and chips too easily.

    I've used Zinc 182 and then sprayed over it with hycote double acrylic. That lasted years just behind the front wheels where it tends to get grit blasted from stones off the front wheels. But, I have since given the whole underside a couple of coats of Bilt Hamber Dynax UB and inside cavities Dynax S50.
  8. Saxperience Forum Bum Joined: Mar 2009 Stoke-on-trent Posts: 2640 Mk5 Golf GTTDI Mk2 VTR Project
    #8
    Quote:
    Originally Posted by Healey View Post
    I've found Hammerite/Smoothrite to be a waste of time, It's too hard and chips too easily.

    I've used Zinc 182 and then sprayed over it with hycote double acrylic. That lasted years just behind the front wheels where it tends to get grit blasted from stones off the front wheels. But, I have since given the whole underside a couple of coats of Bilt Hamber Dynax UB and inside cavities Dynax S50.
    Yeah Hammerite seems to do an awful job seeing as its such a well known brand and its not exactly cheap either, didn't last 5 minutes!

    Will check those out aswell cheers
  9. Saxperience Forum Bum Joined: Mar 2009 Stoke-on-trent Posts: 2640 Mk5 Golf GTTDI Mk2 VTR Project
    #9
    Quote:
    Originally Posted by stevo67 View Post
    No not always it's a personal preference,you can if you want to but not necessary mate.
    I'm considering this and then some kind of underseal over the top possibly
  10. Frequent Poster Joined: Dec 2002 United Kingdom Posts: 700 Mk6 Golf GTD Saxo VTS Project Rally Car
    #10
    I did two coats of red oxide, two household undercoat, and then two household Gloss, cheap and easy to touch in when it chips.
  11. Saxperience Forum Bum Joined: Mar 2009 Stoke-on-trent Posts: 2640 Mk5 Golf GTTDI Mk2 VTR Project
    #11
    Is red oxide ok to go over pitted metal? I plan on using phosphoric acid first to hopefully convert the rust
  12. L-plater Joined: Sep 2015 Posts: 48
    #12
    Best thing to d o is cut rust out get new metal welded in then underseal

    You are chassing rust after it starts

    Sent from my GT-I9100 using Tapatalk
  13. Established Member Joined: Aug 2012 Posts: 2009 Saxò VTS 16v
    #13
    What about red oxide as primer,Dynax-ub for protection against rust and Hammerite as top coat in a color of your choice?
    1 user thanked this post:
  14. Saxperience Forum Bum Joined: Mar 2009 Stoke-on-trent Posts: 2640 Mk5 Golf GTTDI Mk2 VTR Project
    #14
    Quote:
    Originally Posted by gerrankin View Post
    Best thing to d o is cut rust out get new metal welded in then underseal

    You are chassing rust after it starts

    Sent from my GT-I9100 using Tapatalk
    I will be cutting out the badly affected areas but I think there will probably still be bits here and there of light pitting in places
  15. Frequent Poster Joined: Dec 2002 United Kingdom Posts: 700 Mk6 Golf GTD Saxo VTS Project Rally Car
    #15
    Quote:
    Originally Posted by Ben_SaxoForte View Post
    Is red oxide ok to go over pitted metal? I plan on using phosphoric acid first to hopefully convert the rust
    I had mine on a spit and took the floor back to bare metal.
  16. Saxperience Hardcore! Joined: Dec 2007 smurfland. Posts: 17346 Ex saxo owner.
    #16
    Quote:
    Originally Posted by Ben_SaxoForte View Post
    Is red oxide ok to go over pitted metal? I plan on using phosphoric acid first to hopefully convert the rust
    Yes in a word mate.
  17. Saxperience Forum Bum Joined: Mar 2009 Stoke-on-trent Posts: 2640 Mk5 Golf GTTDI Mk2 VTR Project
    #17
    Quote:
    Originally Posted by SGregg View Post
    I had mine on a spit and took the floor back to bare metal.
    It will be back to bare metal just I have a few areas where the rust has left some light pitting in the surface, not bad enough that its softened the metal though
  18. Established Member Joined: Aug 2012 Posts: 2009 Saxò VTS 16v
    #18
    Quote:
    Originally Posted by Ben_SaxoForte View Post
    It will be back to bare metal just I have a few areas where the rust has left some light pitting in the surface, not bad enough that its softened the metal though
    For pitting on surface I would suggest trying to use Bilt Hamber Electrox,it's a primer and i've heard good things about it,it's pretty thick and should help cover any pitting left from the rust,at least the majority of it.
  19. Established Member Joined: Aug 2012 Posts: 2009 Saxò VTS 16v
    #19
    Quote:
    Originally Posted by VeiRoN View Post
    What about red oxide as primer,Dynax-ub for protection against rust and Hammerite as top coat in a color of your choice?
    Never mind,Dynax-Ub is not designed to be painted over,by the way it dries to a matte black finish not brown as I've mistakenly stated previously.

    Would 2 coats of red oxide and 2 of hammerite instead suffice as protection?
  20. Saxperience Forum Bum Joined: Mar 2009 Stoke-on-trent Posts: 2640 Mk5 Golf GTTDI Mk2 VTR Project
    #20
    I will be going with the red oxide for primer i'm a bit suspicious of using hammerite again though as it seemed to just let moisture right through it last time I used it. Considering maybe using some POR 15 as it seems to have good reviews
  21. Established Member Joined: Aug 2012 Posts: 2009 Saxò VTS 16v
    #21
    Quote:
    Originally Posted by Ben_SaxoForte View Post
    I will be going with the red oxide for primer i'm a bit suspicious of using hammerite again though as it seemed to just let moisture right through it last time I used it. Considering maybe using some POR 15 as it seems to have good reviews
    I know,the thing is I would like to use paint that is suitable to use with a brush,I'm not looking for a perfect finish just good protection from rust,I know of other products that would be more suitable (Dynax-Ub is one of them) but they are all more of an underseal rubbery finish than just a plain top coat finish which is what I would like to go with.

    I have a picture of the axle I'm refurbishing and just decided to go with 2 coats of "No Nonsense" red oxide primer,this is just 1 coat waiting for it to dry but it seems like a nice product,still unsure on what to use after:

  22. Established Member Joined: Aug 2012 Posts: 2009 Saxò VTS 16v
    #22
    Quote:
    Originally Posted by Ben_SaxoForte View Post
    I will be going with the red oxide for primer i'm a bit suspicious of using hammerite again though as it seemed to just let moisture right through it last time I used it. Considering maybe using some POR 15 as it seems to have good reviews
    If you're just going to protect the boot floor I would just use 2 coats of red oxide and 2 of Dynax-Ub,the Hamber product is pretty good stuff and should protect from rust pretty well and it's designed to resist debris and stuff thrown from the road.
  23. Saxperience Forum Bum Joined: Mar 2009 Stoke-on-trent Posts: 2640 Mk5 Golf GTTDI Mk2 VTR Project
    #23
    Quote:
    Originally Posted by VeiRoN View Post
    I know,the thing is I would like to use paint that is suitable to use with a brush,I'm not looking for a perfect finish just good protection from rust,I know of other products that would be more suitable (Dynax-Ub is one of them) but they are all more of an underseal rubbery finish than just a plain top coat finish which is what I would like to go with.

    I have a picture of the axle I'm refurbishing and just decided to go with 2 coats of "No Nonsense" red oxide primer,this is just 1 coat waiting for it to dry but it seems like a nice product,still unsure on what to use after:
    Looks pretty good that does, yeah that's pretty much what I'm looking for aswell just something brush on that's going to leave a good solid finish, after all its underneath the car doesn't need to look amazing. I don't want to use rubberized coating either on the boot floor as I think there's a good chance it would end up trapping moisture between it since there are alot of tight corners and seams under there
  24. Frequent Poster Joined: Dec 2002 United Kingdom Posts: 700 Mk6 Golf GTD Saxo VTS Project Rally Car
    #24
    Quote:
    Originally Posted by Ben_SaxoForte View Post
    I will be going with the red oxide for primer i'm a bit suspicious of using hammerite again though as it seemed to just let moisture right through it last time I used it. Considering maybe using some POR 15 as it seems to have good reviews
    If you use POR-15, don't get any one you, it's a bitch to get off skin and the brush will dry rock hard if you don't buy the proper brush cleaner.
  25. Saxperience Forum Bum Joined: Oct 2004 South Posts: 3638
    #25
    the biggest problem with underseal is people apply it too thick.... it wont dry and will start to fall away after a few months..

    using a compressor and a paint gun apply a thin coat
  26. Saxperience Forum Bum Joined: Mar 2009 Stoke-on-trent Posts: 2640 Mk5 Golf GTTDI Mk2 VTR Project
    #26
    Quote:
    Originally Posted by SGregg View Post
    If you use POR-15, don't get any one you, it's a bitch to get off skin and the brush will dry rock hard if you don't buy the proper brush cleaner.
    I have gone with the POR 15 for the underside of the boot but when doing a bit of research ive found people saying it should only be applied to bare metal/rust which is a bit of a bitch as it looks like I'm going to need to get every last bit of paint off, hopefully it will be worth all the work..
  27. Saxperience Post Whore Joined: Jul 2010 Morley, Leeds Posts: 8469 Civic ep3 type r powered by TDI NORTH
    #27
    Under seal is wank now has been for years. The best stuff now by a million miles is upol rapture.its a 2 pack spray on under body/truck bed coat can be applied smooth in a spray gun or textured using a stone chip gun, it's impossible to chip as it stays in a rubbery form. I used it on my civic just jet washed with a steam cleaner and some chemical guys orange degreaser then scotched with a red scotch with thinners to lubricate. Then just masked up the break lines fuel lines and tank then sprayed. It's also tintable so can make it match.
  28. Saxperience Forum Bum Joined: Mar 2009 Stoke-on-trent Posts: 2640 Mk5 Golf GTTDI Mk2 VTR Project
    #28
    Quote:
    Originally Posted by Bedford126 View Post
    Under seal is wank now has been for years. The best stuff now by a million miles is upol rapture.its a 2 pack spray on under body/truck bed coat can be applied smooth in a spray gun or textured using a stone chip gun, it's impossible to chip as it stays in a rubbery form. I used it on my civic just jet washed with a steam cleaner and some chemical guys orange degreaser then scotched with a red scotch with thinners to lubricate. Then just masked up the break lines fuel lines and tank then sprayed. It's also tintable so can make it match.
    Does look like good stuff, is it safe to be using 2 pack stuff without air fed breathing gear though?
  29. Saxperience Forum Bum Joined: Mar 2009 Stoke-on-trent Posts: 2640 Mk5 Golf GTTDI Mk2 VTR Project
    #29
    Thought i'd update this to show some of you who may be interested, I've gone with the POR-15 for the boot floor, wire brushed, sanded and then sprayed with phosphoric acid before applying the POR-15 and this is how it came out i'm pretty very happy with it so far and it feels nice and smooth and seems to be a nice solid covering.

    Ignore all the holes it hasn't been shot by a machine gun that's where I drilled all the spot welds out to remove the beams which were totally rotten.. will be welding some new pieces in when I get a chance and its not raining! next is to remove the fuel tank and do the same to that area