Thick rubber underseal

[RaceDiagnostics]

A couple of hours work from yesterday.

http://www.racediagnostics.com/gallery/index.php?/category/4#&ui-state=dialog

 

[postie jon]

personally i would try WURTH products ,expensive but good, its defniatly a spray on sealer ,
just google wurth paintable body sealent or spray sealent

 

[Dcal]

Yes, it's jotuns epoxy. Removing factory rubber is a pain but it's a pleasure compared to removing bitumen which is a total batch!

Also I want to have the underside painted rather than being covered in tar.

Totally agree.
Tar has no place on a car restoration IMHO

Did you use a wire brush in a grinder to get all the under seal and primer off?
You probably have done it already, but the only thing I would add is - try to get the finish on the steel as rough as possible before applying the primer.

Grit blast (even a spot blaster) is excellent but a mess, - bristle blaster next best (rcx132 uses one I think) - then if the other options aren't available - sand with 80 / 100 grit paper to get a key before the Jotan.
Certainty won't hurt and well worth doing after you've gone to all that work

Great work as usual

 

[rcx132]

But he has used an epoxy primer (and it looks like Jotan 87 paint) and then top coat. The stone chip at least give a factory "look" (If not the performance of the 2 pack rubber)
Doesn't look like a half solution to me and it's way better than using Bitumen.
You say it's easy to remove (not my experience) but if so, why would you even put it on?

I agree stone chip is not as good as the the two pack rubber coating but it will probably have better performance than what was installed at the factory - because it will all be covered.
I would not like the job of trying to get that little lot off again!
Removing the factory under seal would be simple by comparison.

I did exactly the same on my 75 and there is far more protection on it now then when it left the factory.
RD's is a Merc (I think) so will have better quality control from the factory, but it still failed. (With the Alfa - paint or under seal on the whole thing is a huge bonus)
Unless he's thinking of running it flat out on gravel rally stages I think that will last longer than the rest of the car.

Having said all that I do like the look of the 3M 2 pack stuff and am thinking of trying it out, but am put off by the cost.
You could easily spend more on under seal than the paint for the shiny bits.

Anyone tried the Wurth stuff?
Don't know if it's any better and it hard to track down over in NI

Sorry I didn't realise there was Jotun already on there, so all that is needed is something soft to dissipate stone chips.

I found stone chip a nightmare to remove. Took two days to get it all off my car body, another day or two to get it out of all the crevices, and another day to do the chassis. It wasn't easy!

 

[Dcal]

rcx132 Is that not a good thing?
If I put something on I want it to stay on, but I feel your pain.

The usual suspects for coatings coming off is lack of preperation but too much build can also be a problem especially if it's rock hard and as you say a softer coating is better but bitumen is the work of the devil. Only thing going for it is its cheap but it can lose adhesion and hold water better than anything.

I'm going to apply some of the heavy duty wax over my stone chip.
Not pretty, but it's another line of defence and has a certain amount of self-healing properties.
Also a total pain to get off at a later date.

 

[Dcal]

personally i would try WURTH products ,expensive but good, its defniatly a spray on sealer ,
just google wurth paintable body sealent or spray sealent

Thanks Posti Jon, it's probably worth a try but as rcx132 says I've found them all much of a muchness.
I thought the 3m didn't dry solid then left it another couple of months and it was also rock hard.
If you want soft (like oem) as far a I can see you have to spend big money like £120 per litre for the 3m and that's before buying a gun.

I did once see a video of a guy applying normal pu seamsealer then blowing high pressure air from a normal blow jet to get a oem finish.
It did work but I don't fancy doing the whole underside of car.

But never say never.

 

[rcx132]

rcx132 Is that not a good thing?
If I put something on I want it to stay on, but I feel your pain.

The usual suspects for coatings coming off is lack of preperation but too much build can also be a problem especially if it's rock hard and as you say a softer coating is better but bitumen is the work of the devil. Only thing going for it is its cheap but it can lose adhesion and hold water better than anything.

I'm going to apply some of the heavy duty wax over my stone chip.
Not pretty, but it's another line of defence and has a certain amount of self-healing properties.
Also a total pain to get off at a later date.

At the time, my impression was that the aftermarket products wouldn't really give anything like the OEM protection. I had gone back to bare metal and put on lots of primer and topcoat and just wanted something soft on top to disspiate stone chips. In the end I just put on bitumen. The bitumen didn't work as well as I thought, I couldn't get it on as thick as I wanted to dispiate energy but it's done now. I'll be starting my next restoration soon so got think which method I'll use on that. The 3M stuff sounds good but I'm also tired of buying equipment, i.e. another gun for it. So I'm not sure which method is best.

 

[Dcal]

This thread has got me thinking (never a good thing) and I might have a go at spraying seam sealer.
I have a cheap gravity gun with a 2.5mm nozzle. If I thin the seam sealer, not sure with what yet (2k thinner?) but it might work. Whether it will dry through is another thing but why not?
I also have an air powered seam sealer gun that takes 600cc sausages so would be able to get the pu to a nozzle but I don't think it will work great without thinning / heating or both.
I can also get other "construction" sealers which might be worth a try. (poly sulphide?)

I'm away for a weeks hols but will report back when I've had a go.

Anyone else tried It?
Am I mad (no real need to answer that)

 

[RaceDiagnostics]

I found another rubber underseal, SikaGard® -6440, it looks similar to the Dinitrol 447

https://gbr.sika.com/sealantsandadh.../protective-coatings/Stonechipprotection.html

 

[lexi]

That Sika looks like what you are after. A spray on low mod polyurethane.

 

[james butler]

the gravitex is great stuff
but something that is simply awsome but rediculously expensive and now getting rare to find is origenal vw underseal, it sets into rubber and is nigh on indestructable stuff.
only thing that seems to fetch it off is heat or if the metal its own corrodes away.
i have a feeling it has something nasty in it wich is why its getting very hard to come by.
https://www.google.co.uk/search?q=g...AhWEzaQKHWBlAEQQ9QEIKTAA#imgrc=XKIHFGZ4z-XzKM:

 

[rcx132]

Sika products always seemed good to me and well priced.

 

[julianf]

Saw this whilst out today -

Anyone used it?

(its available cheaper elsewhere)

Can reckons it does 1.8mtrs of coverage.

 

[RaceDiagnostics]

OK, after the old rubber and bitumen was stripped off I had this, what a nightmare getting it off.

Jotomastic 87.

Dinitrol 447, rubberised overpaintable stone chip, it went on easy apart from my restricted access and I was able to get a very high build.

Close up.

2l needed for the floor pans
.

 

[bricol]

I really hope that works - but epoxy paint on a lovely smooth surface like that I found simply detached in large flakes/sheets allowing moisture behind it. Areas I blasted, as per the paint instructions were still attached as per the brown stuff to a blanket 10 yrs later.

 

[Ianb]

The underseal looks good, how many coats did it take to get that build thickness? How long do you have to leave it before painting over?

 

[RaceDiagnostics]

I really hope that works - but epoxy paint on a lovely smooth surface like that I found simply detached in large flakes/sheets allowing moisture behind it. Areas I blasted, as per the paint instructions were still attached as per the brown stuff to a blanket 10 yrs later.

I've been using jotuns for years with no problem.

 

[RaceDiagnostics]

The underseal looks good, how many coats did it take to get that build thickness? How long do you have to leave it before painting over?

One coat, I will leave it a few days before painting.

 

[J.B. Welding]

I'll seconds the Wurth stuff as it sprays out well and its nice and thick.

For priming/intermediate coating the best glass flake epoxy I've used is

https://www.promain.co.uk/specsheets/TM922.pdf

Sherwin Williams, formerly Leights recipe it's used on oil rig legs so you know its good, scoops out rather than pours out of the tin, the hardener thins it to a thick paint you can brush on. Potent stuff wouldn't like to spray it.
I've rusty beams around that I've used to cleaned brushes on 10 years ago, still painted.
Has a long shelf life from the look of it too, priced for special jobs only think I need to use mine up on the tranny s(c)ills before its too late!

 

[Dcal]

I'd be really interested to see how the 447 dries.
Will it stay soft and flexible like the under-seal you removed? It certainly "looks" right.

All the stuff I've tried, dries rock hard eventually and I'm still looking for something that doesn't.

Here's hoping