# Underbody refresh project



## alexanderfitu (Jan 4, 2015)

Hi all

I am about to tackle an underbody refresh on a W215 CL55 AMG

Everything is coming out (engine/box drivetrain, subframes etc) and all rust underneath is going to be treated etc.

The problem is, there is a combination of good, painted underside areas still in factory underbody paint and there are areas that are really rusty (but no holes).

I plan to flap wheel all the rust, then treat with Bilt Hamber Deox Gel, then etch prime and paint (or epoxy prime and paint?). I understand that if I key the non rusty surfaces ok, I can do this process on both the rusty stuff and the non rusty painted surfaces.

However, some people are advising I use POR15 as its rock hard and will last forever but I have 2 reservations.

1. POR15 is quite thick and this will be a pain around underbody mounting points, thread areas, brackets etc
2. POR15 does not stick to painted surfaces very well, meaning I will have to combine two methods.

Any thoughts or guidance would be very much appreciated, as always.

Some pictures to give you an idea


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## steveo3002 (Jan 30, 2006)

id never used por15 again...epoxy primer like jotun /rustbuster will work great if the rust is cleaned up

ive used por before, when you get it right it does stick well and goes hard like rock , but more often than not its not right and peels off in sheets vw epoxy is more tolerant and will work well over most prep


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## alexanderfitu (Jan 4, 2015)

Very much appreciated, I was going down that road in any case, and feel that it should last as long as POR does, but cover better in corner areas where prep may not be 100%.


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## steveo3002 (Jan 30, 2006)

works great...show me how many pro restoration shops use por15...yeah none


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## alexanderfitu (Jan 4, 2015)

steveo3002 said:


> works great...show me how many pro restoration shops use por15...yeah none


Good point. Our bodyshop says to use epoxy prime as well.


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## conor (Jun 28, 2020)

Yes to epoxy primer.. after doing plenty of research, it seems to be the modern approach.

I've actually decided to go with Epoxy Mastic from Rustbuster as it is supposedly fantastic too. Set's harded than the epozy primer, but can't sand it. It's going underside, so doesn't bother me.


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## alexanderfitu (Jan 4, 2015)

So the question now is 1k or 2k (with all that it entails safety wise, air fed respirator etc)

Rustbuster is 2k and 2k is dangerous to spray inside without air replacement or proper venting.....


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## conor (Jun 28, 2020)

alexanderfitu said:


> So the question now is 1k or 2k (with all that it entails safety wise, air fed respirator etc)
> 
> Rustbuster is 2k and 2k is dangerous to spray inside without air replacement or proper venting.....


That's a very good question. To be honest, 2K is the answer to get the job done right...

But isocyanates are real and dangerous. I have an air fed respirator I bought to do this.. but it get's expensive fast as you also need a 3 stage filter to filter down to .01 micron. The 3 stage unit is expensive. Here is the best value one I could find.. I'm not sure if it comes with filters.. but they expensive too.

Now, I will say this. I had heard rumblings of people using charcoal filters with 2k/Isocyanates and have been fine. I was dubious, but came across Trev on Trevs blog saying they are ok for the weekend warrior.

Let me see if I can find it..... ok. Here is where he starts talking about respirators.

He basically says his face mask with activated charcoal filters are fine for Isocyanates. To be completely honest, i'm all for safety first and not scrimping, but enough is enough. I've spent a shedload on tools for my project and I want it to stop. I'm thinking of binning off the breathing mask and just using a regular charcoal mask based entirely on Trevors recommendation. I think I will check out the SDS on some 2k products also, but I am veering heavily in that direction.






EDIT: Need to ensure rest of your body is still covered.

EDIT2: Also need to keep in mind, Trev seems to have built in some decent extraction into his setup. So if you don't have this, then perhaps you (Me) need to think a little more about how well the charcoal will protect you. Going to look into this now.


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## steveo3002 (Jan 30, 2006)

epoxy isnt isocyanate ...no need for air fed masks

if you havent already bought it , then jotun is VERY similar to rustbusters product , very very similar , but cheaper


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## conor (Jun 28, 2020)

steveo3002 said:


> epoxy isnt isocyanate ...no need for air fed masks
> 
> if you havent already bought it , then jotun is VERY similar to rustbusters product , very very similar , but cheaper


Ah right.. I just saw isocyanates and went off on one


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## alexanderfitu (Jan 4, 2015)

steveo3002 said:


> epoxy isnt isocyanate ...no need for air fed masks
> 
> if you havent already bought it , then jotun is VERY similar to rustbusters product , very very similar , but cheaper


Yup, did some research, Isocyanates are the dangerous stuff, and the 2K stuff I plan to use (Upol Raptor) Does not contain it, so just the usual precautions should be fine for it 

Thanks all


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## Andy from Sandy (May 6, 2011)

I thought I had saved a link and I wish I could find it but I was reading about a mask that works for 2K paint and is not air fed. It is designed for small applications like a DIY job. The information as I recall gave the time limit on its use before the filters needed changing.


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## conor (Jun 28, 2020)

Andy from Sandy said:


> I thought I had saved a link and I wish I could find it but I was reading about a mask that works for 2K paint and is not air fed. It is designed for small applications like a DIY job. The information as I recall gave the time limit on its use before the filters needed changing.


I think any good carbon filters will work against Isos.. I think the main thing is to not leave them around in open air before use.

I think once the sealed pack is opened, the carbon starts binding to all the impurities in the air around it, and over time will become spent. I think it helps to keep the filters in a sealed unit between uses. But yea, I think the TDS for each filter should advise on timings.

That's what I plan on doing now.


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## Ianbuckwell (Dec 23, 2011)

alexanderfitu said:


> Yup, did some research, Isocyanates are the dangerous stuff, and the 2K stuff I plan to use (Upol Raptor) Does not contain it, so just the usual precautions should be fine for it
> 
> Thanks all


Check the Raptor data sheets and here under 'Technical properties and chemical composition' faq, the hardner part DOES contain isocyanates, so go careful.

https://www.raptorcoatings.com/uk/en-uk/faqs#.Yghj6lOnwVE


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## Tintin (Sep 3, 2006)

The masks that you can use with 2k can be used for a maximum number of hours and must be stored correctly. I have this one by Gerson and have used it with 2k non iso primers, aerosols etc, though not with 2k isocyanate paints Seems to work really well.

https://nuagane.co.uk/product/gerso...repair-2-pack-car-industrial-paint-free-post/


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## Ianbuckwell (Dec 23, 2011)

I have used Gerson masks for all my projects with isocyanate containing 2K paints and had no I'll effects (not yet anyway!)


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