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Sealing Bare Metal Prior to Painting
hulbyw - February 16th, 2014 at 09:00 PM

Apologies if this has already been covered. I am considering removing all the paint on my Beetle and treating any surface rust myself, rather than paying a professional.
Question, is there anything I can seal the bare metal with to stop it rusting before the car is trailered to a professional painter for a 2pak paint job. 10 years ago I stripped the roof, painted it with etch primer then undercoat and then acrylic top coat, however now there is a small area of surface rust under the paint and I want to avoid that happening again. I am guessing I didn't get the top coat on fast enough before some moisture got into the primer
Cheers...............Wayne


cam070 - February 16th, 2014 at 09:45 PM

I think the POR15 guys do something along these lines. Check out the advert in VWMA mag for more details.


HappyDaze - February 17th, 2014 at 07:40 AM

I've used Kephos [now called Paint-grip 253, I think] a few times, and it seals bare metal for months. It washes of easily when ready for painting. A friend had a 20 litlre drum of it, so it worked out economical.....otherwise it's expensive. JUST DON'T INHALE IT ! :td:


68BUS - February 17th, 2014 at 08:16 AM

If you are going to go with 2 pac then the best bet is to use an epoxy primer.
If you are blasting it yourself you can solvent wipe and then epoxy eaxy panel the same day.
Otherwise get some deoxidine (rust converter).

-Cut and strip the panel.
-Wire wheel inside the seams (preferable to do this with a small blaster to aid adhesion as the wire wheel will smooth the metal too much.
-Deoidine as per instruction.
-Use watero dilute / wash of deoxidine (it is an acid).
-Use metho to dry the water.
-Use compressed air to dry the metho.
-Wax and grease remover before paint.
- Then use a epoxy primer. I have just sent my blaster Dupond 840r. For a 4.5 litre kit plus 5ltrs of thinners it cost me about $260-300.

The epoxt undercoat is brilliant. They can lightly score the surface to aid adhesion of body filler. At the end of the day they will need to epoxy prime again to etch into it and then change to their high build primer within the 3days of it fully curing.

It is a long process but you only go back to bare metal once (if you have done it right anyway) then at least the first stage id done right without any shortcuts. If you pay for a cheap paint job after that (not saying you will) at least your paint may deteriorate in 5 years but your metal wont.

This is a good article on it.
http://www.v8.co.nz/articles/proper-paint-preparation-85 


68BUS - February 17th, 2014 at 08:20 AM

The other thing that I forgot to mention. After long consultation with a mate who is an old school painter my current bus got extra treatment before going to the blasters.
Because the blast media will not get into all the seems and the epoxy primer is a bit thick to do the same I scratched out all the seams, panel joins etc... basically anywhere metal meets metal.
I then flooded every bit with penatrol. Every seam, window sill, behind fuel tank, roof gutters etc.....

That way once the blasting and epoxy if finsihed any little bit of steel that does not get epoxy covered will have penatrol on it anyway. The blasting will take off any penatrol that is on the outside od the seams so that paint adhestion is not affected (not that is matters I think).


grinderman - February 17th, 2014 at 09:27 AM

I am using the same DuPont 840r epoxy primer surfacer on the 57 splitty project and it grips like shit but it still sands nicely, so I can definitely recommend it.


helbus - February 17th, 2014 at 05:43 PM

I recommend 408 Protec epoxy. Now called Barrier 408 Protec epoxy
It is a PPG product and if you do a search for Barrier 408 Protec epoxy on Google or Youtube you will see more info. You can put body filler over it, and it is a better way to do the fine filler repairs with the epoxy under the filler. All the resto cars we have to do that were 'restored' 20 plus years ago all have rust on the steel under the filler where it is on bare metal. Filler attracts moisture, and on bare steel it will rust.
Epoxy can be left on a panel for months and no moisture will get in. Then sand it with a block, fine fill any lows or ripples, and then prime and paint. You cannot paint directly over epoxy.


68BUS - February 17th, 2014 at 06:49 PM

I wish more body shops worked like you. Filler on bare metal is a recipe for disaster in Australia. To humid to begin with.almost guaranteed moisture in it from day dot.


helbus - February 17th, 2014 at 07:17 PM

We don't do modern crash work, only resto work, and damage repair to already restored cars. Aluminium, steel or fibreglass panels

Currently I am working on the restoration of a 1937 Cord 810, 1954 RHD Kombi, and the other panel beater is doing a 1964 Ferrari 330 and 1967 Mustang fastback.

In the paint shop is a 1955 Alvis Graber, 1955 Bristol 404, Healey Sprite, 1960's Lotus Elan roadster and BN2 Austin Healey.

In assembly is a Mk7 Bolwell, FJ Holden ute, 1972 Bristol 411, Austin Healey BJ7

We have recently done damage repair to an EH Holden, Pandarus Kit car, Leyland P76, Austin Healeys, Triumph Spitfire, Aston Martin DB5.


hulbyw - February 17th, 2014 at 07:18 PM

Thanks folks for all this usefull info. However if I use epoxy, I will need a correct gun, a ventilator and maybe some skills I don't have. I was thinking more of something I can put on that can be washed off later when the car is painted professionally.
Greg's suggestion of Kephos sounded good until I read all the warnings. Sounds like very aggressive stuff.
Cheers


68BUS - February 17th, 2014 at 07:37 PM

Don't be put off. Epoxy is not great to breath. That is true.
But if you are not spraying at home then get a good carbon filter mask and spray outside. A cheap hvlp gun for $50,is good enough. Runs will get rubbed out anyway.

If you are at home you might be able to brush it on????

Otherwise a single pack with have less fumes and over spray but will soak in moisture if wet or humid.
This is the one time not to skimp. If your bare metal do it right and spend less on interior or mechanical. You can't save up later for rust proofing.

Worst case something like lanolin maybe worth looking into. I have heard that the chemical dipping companies coat things in lonolin. It would have to come off though.

Also penatrol is another brush on option. Can get from domestic paint shops in 5&20ltr drums.
If is brilliant. But probably my need to be stripped bare by paint shop


hulbyw - February 17th, 2014 at 08:43 PM

Yep, working at home in the 'burbs, so spraying epoxy is not really an option (for me anyway). I had forgotten all about Lanotec. I will also check out brushable or rollable (is that a word?) epoxy and Penatrol
Cheers


helbus - February 17th, 2014 at 09:53 PM

In Australia in the 'burbs you can spray epoxy. A cheap WorkQuip brand gravity spray gun at about $90 and you are up and running.


68BUS - February 18th, 2014 at 08:14 AM

How much over spray is there on epoxy Helbus?
I never took any notice cause I sprayed it at work. I know the floor copped some but I was spraying right down to it.


helbus - February 18th, 2014 at 05:37 PM

I use masking plastic around all walls of the garage and on the floor, as the epoxy sticks to everything.


vlad01 - March 18th, 2014 at 10:51 AM

I been experimenting with rust bullet automotive formula.

works unbelievably good. sticks to existing e-coat and primers like dog shit and seals repair work well and truly.


68BUS - March 18th, 2014 at 12:24 PM

The only downside to Rust Bullet (literally the only one I think) is the fact that it does not take paint over it easily.
They have good instructions. Basically once it is set it goes to hard for a lot of things to stick to it.
You either have the option of painting the etch / undercoat onto it within 3 days I think before it fully cures.
Or they sell a product that goes onto it and etches into the surface before you paint your next layer. Or you do a new coat of it.

Easy to get around but as long as you are aware you cannot just spray over most rust bullet products.


vlad01 - March 18th, 2014 at 02:04 PM

Are you kidding? normal primer takes it it great. I find it has a very wide over coat window compared to any one paints I have used. 72 hours they state.

if you are worried, scuff it, or coat with regular primer the next day to provide a linking coat. This is no different to epoxy 2 pak.

I found no issues with over coating it yet. far easier than por15 to work with and over coat.


68BUS - March 18th, 2014 at 02:56 PM

Right you are. I just checked the new MSDS and Application info for the automotive range and they reckon it takes new coatings.
I previously worked with the heavier aluminium content industrial coating and it was quite fickle in what you could put over it and how it had to be done.
I assumed that the auto range was the same but I was wrong it seems.


vlad01 - March 19th, 2014 at 01:34 PM

its good stuff. I tryed etch primer on it and stuck really well, even 1.5 weeks latter from application.

I personally think regular primer will stick better. Might try that tonight.

All my test have been done way outside the re-coat window so I am impressed with the results. Within the re-coat window I would imagine it be impossible to remove off the rust bullet.


vlad01 - March 24th, 2014 at 03:02 PM

My testing= light sanding of RB and any auto primer will stick like dog crap without using any prep solvent, no problems at all! Tried this 2 weeks after RB first application.

So if done as per usual sand and prep solvent, you can't go wrong.