Car rustproofing

[Gerard Fazzini]

I know there are several threads on here covering this subject but I'm still confused by the myriad of products/ideas relating to this and the order of application.
I'm welding up the inner and outer sills of a Nissan Micra and I want it to be bombproof so I don't have to do it again within the next few years.

So, over the newly welded metal and surrounding grinded surfaces, do I use:

POR 15 or Dinitrol or Jotamastic 87 or Rustbuster 121???

Can all of these be overpainted or do they even need to be overpainted?
I'll need a decent painted finish on the outer sills but as long as the underside is protected against rust, I don't care how it looks so what's best to cover the products I listed?

In days gone by, I'd have used a combination of the Hammerite products but these seem to be outdated now and I was never really impressed by their long term effectiveness against rust.

Hope someone can help!!

 

[RaceDiagnostics]

I have used Jotamastic Smartpack / Rustbuster 121 (same product) where it can't be seen as it goes on nice and thick.

The advantage of 121 is that it can be purchased in small quantities but has a huge mark up.

Jotamastic 87 is good but a bit of a pain to mix in as its not 50/50 and available in reasonable tin sizes, that's what I'm using on the underside of my car at the moment.

I then put dinitrol over the top of the epoxy, but it can be overpainted if desired. On suspension parts I don't bother overpainting.

For anything that will be visible I would use Lechler epoxy as its much better to spray.

If you plan to stone chip the sills then rollering on 87 or smartpack would be fine as they will end up being textured.

 

[Swift&Bold]

I've done Jotun 87 on the bare metal for the chassis and inside the arches then finished with Gravitex and 2k laquer.

I used Rustbuster 1-2-1 for exposed components which are likely to take a lot of direct impact from stones, gravel etc Front and rear sub frames, suspension arms, brake dust plates and that kind of thing.

The comments above by RaceD are all valid regarding price and mixing. I find the 1-2-1 to be the toughest as in goes on thicker, the Jotun 87 goes further so is more cost effective but not as thick, hence the Gravitex coating. They are usually sprayed but I applied with a brush, laying on in strokes for the first coat and stipple for the next coat(s), I did this also for the Gravitex and the 2K but only layed on in strokes.

These products are really best for the unseen areas, for body panels or areas you can see use the Lechler epoxy, it'll save you a shed load of work!

 

[Gerard Fazzini]

Does this Lechler epoxy go straight onto bare metal?

 

[steveo3002]

id go with the jotun for painted surfaces , good cavity wax from dinitrol or bilt hamber for where you cant paint

yes epoxys go onto bare metal (or any sound surface)

 

[Swift&Bold]

I've used the Rustbuster Mil Spec cavity wax diluted down for all the cavities.
There're two schools of thought here, either spray the wax in alone or spray in rust converter first then spray the wax in after it.

 

[Gareth J]

Don't forget to do a bit of critical examination of the finances of this project including how long you anticipate it'll live for, it would be quite easy to spend as much on paint systems the cost of buying a replacement Micra. Last time I looked, they were thick on the ground and generally treated as disposable. Of course if this particular little car holds some special significance that's fair enough. In fact, fair enough either way as it's your project and fair play to you for wanting to do it right!

 

[Gerard Fazzini]

Yeah, the car is very special to her indoors. If I can rustproof it for under £100, I'll be happy as the welding is costing peanuts. There are loads of Micras around but very few with sound bodywork, believe me I've looked. Thanks for the advice guys. I've got a better idea what to use now.

 

[Gerard Fazzini]

Right, decision made: 121 on the inner sills and underneath, Lechler epoxy on the outer sills. The Jotun 87 is far too expensive. Thanks folks.

 

[bricol]

Just a thought. 12 yes ago I had various bits of an integrale blasted to quickly clear surface rust. This obviously left a clean and well keyed surface just right for applying epoxymastic. So I did.

I also applied it to areas I had only attacked and cleaned with wire brushes in angle grinders.

Earlier this year (or was it last? Time flies when waiting 7mths for a 2 week bonnet repair) I had opportunity to inspect things as I dismantled the car for a bit of TLC.

The blasted metal is still covered in pretty perfect epoxymastic. Odd stone chip but nothing much at all. The areas painted onto sound, but not blasted areas were rather less perfect. Rusty. Whole sections detached. Sections missing. ie not just small chips, whole sections, several square inches in area loose, detached or missing.

I can't remember the instructions for epoxymastic, but certainly the Jotun stuff says abraded or blasted to a certain spec to give a good key. I've used Jotun this time after sill replacement on blasted bits, and zinc rich primer on non-blasted areas. Guess I'll see in another 12 years . . . ;-)

After painting, I used Noxudol 700 anti corrosion wax inside, and applied it with the shell in various positions - upside down, sideways, and right way up, to try to get it to creep into every panel gap.

 

[Burdekin]

Just a note, epoxy doesn't like heat so don't use it on inner sills if welding over. Use a weld through primer inside the sills and then liberally coat the inside with a good quality cavity wax.

If you're just painting the sills just use the one primer, no need to get two for a small job. 121 technically should stick better and Lechler sprays better, both will offer good corrosion protection.

 

[steveo3002]

121 is very very similar to jotun....some might suggest its the same thing decanted into smaller tin

 

[Gerard Fazzini]

Just a thought. 12 yes ago I had various bits of an integrale blasted to quickly clear surface rust. This obviously left a clean and well keyed surface just right for applying epoxymastic. So I did.

I also applied it to areas I had only attacked and cleaned with wire brushes in angle grinders.

Earlier this year (or was it last? Time flies when waiting 7mths for a 2 week bonnet repair) I had opportunity to inspect things as I dismantled the car for a bit of TLC.

The blasted metal is still covered in pretty perfect epoxymastic. Odd stone chip but nothing much at all. The areas painted onto sound, but not blasted areas were rather less perfect. Rusty. Whole sections detached. Sections missing. ie not just small chips, whole sections, several square inches in area loose, detached or missing.

I can't remember the instructions for epoxymastic, but certainly the Jotun stuff says abraded or blasted to a certain spec to give a good key. I've used Jotun this time after sill replacement on blasted bits, and zinc rich primer on non-blasted areas. Guess I'll see in another 12 years . . . ;-)

After painting, I used Noxudol 700 anti corrosion wax inside, and applied it with the shell in various positions - upside down, sideways, and right way up, to try to get it to creep into every panel gap.

That is interesting. Thank you.

 

[Gerard Fazzini]

Burdekin. What is this weld through primer you speak of and where do I get it? I've never heard of it but it sounds perfect. I was always concerned about the effect of the heat on the treated metal inside the sills.

 

[Burdekin]

I normally use Screwfix Zinc Galvanising Spray or Upol weld through primer.

Just note even though you can weld through them, it's best to weld to clean metal. Welding through the primer does cause a fair bit more splatter and makes things harder. The weld through primer is good to spray inside sills, chassis rails etc but clean off any areas where you are welding directly, like plug welding the sills to the floor etc.

 

[Swift&Bold]

121 is very very similar to jotun....some might suggest its the same thing decanted into smaller tin

Apparently the 1-2-1 is repackaged Jotun Smartpack but I personally cant confirm that, the Jotun 87 is different though in both mixing ratio and the hardener component.

 

[RaceDiagnostics]

Here is another observation I have made, smartpack/121 withstands heat better than 87, when welding close to both, the 87 will peal about 1/2 to an inch more than smartpack although the data sheets are the same.

The data sheets say 120 degC for an hour rather than welding temps for a few seconds though.

 

[richie00boy]

The areas painted onto sound, but not blasted areas were rather less perfect. Rusty. Whole sections detached. Sections missing. ie not just small chips, whole sections, several square inches in area loose, detached or missing.

Your issue was not the epoxy, but that wire brushes in an angle grinder leave a burnished finish which is terrible to apply paint to. Unfortunately zinc rich 1k primer will be even worse than epoxy.

I no longer use wire brushes but instead polycarbide wheels. Cost more but at least the effect works. And no flying needles!

 

[Gerard Fazzini]

I normally use Screwfix Zinc Galvanising Spray or Upol weld through primer.

Just note even though you can weld through them, it's best to weld to clean metal. Welding through the primer does cause a fair bit more splatter and makes things harder. The weld through primer is good to spray inside sills, chassis rails etc but clean off any areas where you are welding directly, like plug welding the sills to the floor etc.

If I use weld through primer inside the sills, what would you recommend overspraying it with once the outer sills are welded into place? I can access the cavity with a spray tube from inside the car once the outer sills are on but what's the best product to use? The issue with the Micra is that water runs down inside the door pillars and sits inside the sills.

 

[RaceDiagnostics]

Here is an idea, once the car is perfect, only drive it on dry days, buy another cheap one and run that on the wet days. I think that's what I will have to do on my XK8 as they are rust buckets just waiting to happen.