Under body refinishing advice

Talk about the E-Type Series 1

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IOM42E
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#1 Under body refinishing advice

Post by IOM42E » Wed Mar 22, 2017 12:47 pm

The external underfloor panels of my 67 FHC owned 39 years had a combination of original panel etch primer, some patchy anti-chip and some colour spray-drift two pack following full professional refinishing about 20 years ago. The shop did not finish the underside as they assumed it would be waxoyled or similar.

The under floor panels suffered very little corrosion whilst the car was dry stored inland but now I live by the coast good protection has become an issue.

I have stripped the steel to good metal and following rigorous cleaning and de-salting treatments, I tried an off the shelf tannate emulsion and a non-toxic 2 pack mastic paint system. My paint shop was to apply anti-chip and a 2 pack top coat to finish off.

I now find the tannate will easily scratch off and the 2 pack mastic flakes off with it - could be preparation, but never had an issue with prep. before. There seems to be little adhesion of the blue black tannate emulsion to the steel - and worse, yellow 'rust' coloured patches can be seen under the tannate where there were none before the treatment.

I would have preferred a phosphate wipe to deal with any residual rust followed by a zinc based bonding primer but after researching, gave the tannate a try. Fortunately not on a large area.

I would welcome any views both on the tannate system and recommendations for any other refinishing for the underside of my car.

Very grateful for any comments - Nigel
Nigel
1967 FHC RHD

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mgcjag
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#2 Re: Under body refinishing advice

Post by mgcjag » Wed Mar 22, 2017 2:04 pm

Hi Nigel...what was the emulsion....if something like Kurust its only supposed to go on the rust...if you brushed it all over and have it on some non rusty shiny steel it will not form a good bond and easily scratch off.....the problem with these convertors is that it turns the top layer of the rust black and makes you think you have cured it, but scratch the surface and the rust is still under there
Steve
1969 S2 2+2 & Building a C type replica

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cactusman
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#3 Re: Under body refinishing advice

Post by cactusman » Wed Mar 22, 2017 2:10 pm

I have no direct experience of it but POR15 paint is supposed to be good. It is said to bond better to slightly rusted steel, forms an enamel like layer that is very tough and water proof. I think it comes in black....others may have tried it and can comment. Lots on YouTube about it although it is not cheap. I believe it can be over painted after it is dry but not sure...I would avoid bitumastic under seal. Cracks and traps water....quite the reverse of what you need....
Julian the E-type man
1962 FHC
1966 MGB....fab little car too

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IOM42E
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#4 Re: Under body refinishing advice

Post by IOM42E » Wed Mar 22, 2017 6:03 pm

Thanks for coming back on this new topic Steve.

The product is Rust 123 from Rust UK. Comprehensive user info is on the rust store .com under Rust Converter which is the same product. You are right that the product needs rust to work but it is advertised as suitable for painting on clean steel. From my recent experience, it does not appear to adhere well to the clean steel - something that the user can't know unless you happen to scrape some off - and yes the rust is just under the purple surface.

I am back to clean steel again now so happy to hear any best practice ideas for sealing the external floor panels and rails against the demon rust. Happy days.

Nigel
Nigel
1967 FHC RHD

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IOM42E
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#5 Re: Under body refinishing advice

Post by IOM42E » Wed Mar 22, 2017 6:13 pm

Thanks Julian, I have posted some more info following Steve's response above.

And yes - bitumastic is problematic and I would not use it. The product I have used is a two pack paint that forms a very hard coating - but this is of no use if the substrate coating has not properly adhered.

It is becoming clear that tannate emulsion is for more heavily rusted metal than my external floor rails and panels. Back to clean steel again now so keen to hear any suggestions for paint system so I can discuss them with the paint shop.

Cheers Nigel
Nigel
1967 FHC RHD

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mgcjag
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#6 Re: Under body refinishing advice

Post by mgcjag » Wed Mar 22, 2017 6:31 pm

Hi Nigel....I have had very good results with Eastwoods Extrem Chassis Black.....use the primer on bare clean metal http://www.frost.co.uk/eastwood-extreme ... rimer.html and the Extreme topcoat http://www.frost.co.uk/eastwood-extreme ... quart.html Ive done the underside of my 2+2 and all the IRS components....brush applied and you get quite a good finnish and very easy to use and looks good 8 years on
I have used Por15 but not on the car...underside of my mower etc....it cures rock hard and more difficult to apply, 2nd coat whilst 1st coat is still tacky so ok for small parts....
Steve
1969 S2 2+2 & Building a C type replica

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288gto
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#7 Re: Under body refinishing advice

Post by 288gto » Wed Mar 22, 2017 9:56 pm

Hi Nigel,

Rustbuster sell some excellent products, unfortunately 123 is not one of them. It supposedly acts as a rust encapsulator rather than a rust remover.

Stripping back to bare metal leaving a roughened surface and then painting with an epoxy primer, preferably a zinc based one is your best bet.

The 121 Rustbuster sell is very good, however I can't stress enough how important surface preparation is.

We have painted exterior structural steelwork on buildings exposed to the weather and elements with this product and it is still rust free 5 years later with no signs of it lifting where the paint layer has been compromised by drilling or damage.

I have even burnt areas off while welding and it has only rusted in that damaged area.

For the underside of your car the epoxy once hardened then needs sanding to provide a key for a good rubberized stone chip coating.

I know this isn't really good to say these days but I generally find the more hazard codes a can has on it, the more durable it is.

And a good excuse for me to show off a pic of mine.....sorry. :oops:

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Simon
Simon
1969 S2 OTS

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IOM42E
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#8 Re: Under body refinishing advice

Post by IOM42E » Thu Mar 23, 2017 8:47 pm

Hi Simon

Oh for a jig that exposes the underside of the car - and a car stripped sufficiently to go on one. Very envious. I am working with about 2' of head room but that is ok as any higher increases arm ache! A pillow helps.

The 2 pack mastic I have used is Rust 121 and it does seem to do what it says in the supporting online info. The one slightly negative comment I have read is that the substrate has to be solid because if the painted surface can flex the mature epoxy coat can crack and in the worst instance e.g. bad substrate, flake.

I have since read that it is best applied direct onto clean steel and that it can be applied over 123 (tannate emulsion) where there is no rust present, however this may not produce the best result - see my initial post. Wish I had read some of the threads earlier.

I will try a test section of 121 on clean steel to prove the adhesion as I have plenty of product and update this post. If it fails, I will be trying Steve's suggestion of Eastwood product.

Thank you very much for all contributions. Any other comments most welcome - Nigel
Nigel
1967 FHC RHD

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paulsco
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#9 Re: Under body refinishing advice

Post by paulsco » Thu Mar 23, 2017 8:50 pm

I really like Dinitrol products.

On my Jaguar 340 I prepared the metal with metal prep and painted it with red Bonda primer which is Zink rich and then sprayed on black Dinitrol 4941 which is a textured self healing wax coat.
This was 20 years ago and it still looks good.

On the bottom of my E-Type I decided I would use Rustbuster epoxy mastic 121, but this failed to dry properly and remained slightly tacky.
However I found it impossible to remove, so I sprayed over it with Rustbuster custom epoxy 421 again in red like the original primer. Both of these are waterproof. I intend to spray on the black Dinitrol 4941 after the car is finally sprayed.

As an aside; I found Rustbuster 421 quite expensive, but discovered that it is just re-badged Jotun marine primer (Penguard HB) https://www.smlmarinepaints.co.uk/primers.

I think the 121 is a re-badge Jotun marine primer as well, but I am not sure which one.
I have bought some Penguard HB; in fact quit a lot of it. it is a great high build primer and comparatively easy to sand, is two pack so not affected by thinners and is very durable.
The only down side is it takes ages to dry:-(

Paul
65 Series 1 FHC, 68 Jaguar 340

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Mikael B
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#10 Re: Under body refinishing advice

Post by Mikael B » Thu Mar 23, 2017 9:11 pm

With the risk of being hammered down :hammer: :seeingstars: I have taken another route. I had no plans of driving in snow on salty roads, dirt roads or leaving the car outside for months in hailing rain. So I painted the under body in 2k epoxy primer followed by 2k top coat to glossy finish same as the other parts of the car. Now after 10 years it still shines lovely, only treatment is a good wash down once a year. I can also then easily see any chipping or other issues and correct but it has not been any :shrug:
Cheers
Mikael Berg
S1 OTS-66 Carmen Red; S1.5 2+2-68 Opalescent Maroon

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IOM42E
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#11 Re: Under body refinishing advice

Post by IOM42E » Fri Mar 24, 2017 6:52 am

Thanks Mikael

Can I ask please, what finish did you use on the panel steel before the 2 pack epoxy primer - if any? And could you let me know which brand of two pack you used?

Many thanks again. Nigel
Nigel
1967 FHC RHD

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#12 Re: Under body refinishing advice

Post by Mikael B » Fri Mar 24, 2017 12:57 pm

Hi Nigel,
My panels was new just welded in place.
I sanded, cleaned and sprayed one layer of yellow epoxi CA primer.
After sealed all welding seems and sprayed 2 additional layers of the same primer.
After drying smothered the surface with sandpaper, cleaning and sprayed 3-4 layers with Glasurit 2k paint Carmen red.
That's it.

Added some pictures from internet, this is not my car but the same procedure for the primer and sealing. I did mine with car on axle stands.

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Mikael Berg
S1 OTS-66 Carmen Red; S1.5 2+2-68 Opalescent Maroon

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#13 Re: Under body refinishing advice

Post by Bill B » Sun Apr 02, 2017 5:53 pm

HI,

Timely thread, this is.

My car has been sprayed underside with Body Schotz (?sp). How ever I sprayed the pontoons and floor cross members internallly with Eastwood Chassis Protector. This being very thin I discovered some few "leaks" on the underside. Both sills where they curve under the floor and are spot welded (factory) have small leaking areas.

So now I am suspecting, despite the Body Schotz I must go and run a bead on all the seams. Most seam sealers need to be protected from UV light, so I thought after that a rattle can of some kind of never hardening, self repairing undercoat would both protect from UV and provide additional protection. Some thing of this sort was on the car originally when I got it at least. Or, perhaps the never hardening spray would be enough on the seams that are not leaking, like the foot depressions which were replaced.

Also, are you folks sealing both sides of the welded seams both in the cockpit and under the car?

Thoughts?

TIA
S1 OTS 4.2 1966
I really go to put this thing back together

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64etype
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#14 Re: Under body refinishing advice

Post by 64etype » Mon Apr 03, 2017 2:09 am

I did something similar, but in a slightly different order....stripped the shell, selectively seam sealed interior surfaces, seam sealed outside of new footwells as seams had been treated prior to welding. No other exterior seams were sealed. Then I pumped heated Evaporust treatment for days through all voids s including sills (it leaked out between seams and that's a good thing), thoroughly flushed voids, sprayed in Boeshield...a low viscosity rust protectant (it leaked out of seams....a good thing), after the Boeshield dried Wurthwax was sprayed into all voids...also seeped out of seams...a good thing). At that point I cleaned up the dried rust preventative from exterior surfaces and started with the paint procedure. The bare metal bottom was etched with a Metal Prep (phosphoric acid), thoroughly rinsed and dried, then sprayed with 2 coats of DP90 2 part epoxy. Immediately thereafter (while the epoxy was chemically "open"), two coats of Eastwood Chassis Black (a two part hardened Urethane) were applied. So the top coats are chemically bonded to the epoxy...this is an important consideration. (The tub was on a rotisserie and suspended over a catch basin).

If I decide to apply undercoat later, there's a solid base. I would not seal the outer seams as my intention is to spray Boeshield inside voids every couple of years...and I want it to leach into and through the seams. This is the same reason I would avoid encapsulation products of any kind inside voids...they block penetrant action.
Eric

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Tony
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#15 Re: Under body refinishing advice

Post by Tony » Mon Apr 03, 2017 10:57 pm

My car underbody is just painted the same as the rest of the car and still looks good after 8 years with no rust showing. I keep an eye on the underneath and any chips keep on top of them with touch up. The fact that you can see what is going on under the car help as it is not covered up with sealants etc so hels. If you intending using the car when salt is down then this approach may not work but is is good enough for just wet days.
Tony (E typed)

Tony

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mark10337
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#16 Re: Under body refinishing advice

Post by mark10337 » Tue Apr 04, 2017 11:31 am

I was thinking of adding some sort of underbody tray to act as better protection against the worst of the salt / stone chips that the road throws up.
-Mark

1969 Series 2 OTS, Regency Red
'Life's to short to drive a boring car'

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#17 Re: Under body refinishing advice

Post by 64etype » Tue Apr 04, 2017 3:17 pm

I'm considering protection for the bonnet areas over the front tires. Hot rodders with steel body cars use a rubber/foam padding material to protect against stone dings appearing in the outer surface of the fenders. Removable alternative to undercoating. Probably not a solution for the floor, however.
Eric

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#18 Re: Under body refinishing advice

Post by Bill B » Fri Apr 07, 2017 5:00 pm

64etype wrote:I'm considering protection for the bonnet areas over the front tires. Hot rodders with steel body cars use a rubber/foam padding material to protect against stone dings appearing in the outer surface of the fenders. Removable alternative to undercoating. Probably not a solution for the floor, however.
If I ever get to that point, which seems far away, I would consider Truck Bed Liner just over the wheels
S1 OTS 4.2 1966
I really go to put this thing back together

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#19 Re: Under body refinishing advice

Post by datmony » Sun Apr 09, 2017 11:44 pm

cactusman wrote:I have no direct experience of it but POR15 paint is supposed to be good. It is said to bond better to slightly rusted steel, forms an enamel like layer that is very tough and water proof. I think it comes in black....others may have tried it and can comment. Lots on YouTube about it although it is not cheap. I believe it can be over painted after it is dry but not sure...I would avoid bitumastic under seal. Cracks and traps water....quite the reverse of what you need....

Please do not use POR 15 on your etype. I think this stuff is absolute junk. I used it on a CJ I was restoring years ago. Laboriously followed their overly complex and expensive procedure and the results were terrible. Now..... actually paint this stuff over rust and it is like concrete. You can take a piece of junk steel and cover it and that rust will stop because it is sealed from the air. Paint it on the really nice piece of clean metal next to it and it will literally peal off in sheets despite following their procedure.

It has it's place on the tractor in the field that needs a refresh, the truck frame that isn't worth blasting properly, etc...... on something like this there are far better products in my opinion...... it just can't adhere correctly to good (even roughed up) metal.

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#20 Re: Under body refinishing advice

Post by datmony » Sun Apr 09, 2017 11:52 pm

[quote="64etype"]I did something similar, but in a slightly different order....stripped the shell, selectively seam sealed interior surfaces, seam sealed outside of new footwells as seams had been treated prior to welding. No other exterior seams were sealed. Then I pumped heated Evaporust treatment for days through all voids s including sills (it leaked out between seams and that's a good thing), thoroughly flushed voids, sprayed in Boeshield...a low viscosity rust protectant (it leaked out of seams....a good thing), after the Boeshield dried Wurthwax was sprayed into all voids...also seeped out of seams...a good thing). At that point I cleaned up the dried rust preventative from exterior surfaces and started with the paint procedure. The bare metal bottom was etched with a Metal Prep (phosphoric acid), thoroughly rinsed and dried, then sprayed with 2 coats of DP90 2 part epoxy. Immediately thereafter (while the epoxy was chemically "open"), two coats of Eastwood Chassis Black (a two part hardened Urethane) were applied. So the top coats are chemically bonded to the epoxy...this is an important consideration. (The tub was on a rotisserie and suspended over a catch basin).


I really like this usage of Boeshield. That stuff is amazing. This is a good approach right here. Short of an acid bath, about the best you can do.

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