Under seal - Any tips?

[Bagspacked]

Hi
I’ve recently acquired a 1970 280sl with a very solid and original underneath. It’s recently been suggested that I apply under seal to protect against rust and maintain it well. Has anyone done or considered doing this and if so any tips?

[Shvegel]

If it is solid underneath leave it be.  New underseal is a sign it has been worked on and no one knows what is under there.  A solid car showing original underbody is more valuable. 

[Cees Klumper]

Also, if the underside is original, should it not already have a thick layer of protective coating? You would only add a layer on top of that. I would suggest carefully inspecting that original undercoating for any cracks or lifting, and just spot-address those.

[kampala]

Bags
Here are the responses to the same question you asked earlier. In case you could not find your post.

https://www.sl113.org/forums/index.php?topic=33776.0

[Bagspacked]

Hi Shvegel
My car has absolutely zero rust, very original and very solid underneath. Was recommended to protect it as Ireland & U.K. havent as dry a climate as say California. Car will be garaged but we have rain. Makes sense to have something protecting

[mnahon]

If you plan to drive it in the rain, it's also very important to make sure all the drainage is working well. This is often overlooked and leads to cars rusting from the inside out when water gets in to cavities, like rockers, and has no way of getting out.

Pawel has written a document showing many of the drain passages. Do a search for 'water drains' and you'll find that document as well as lots of other posts with info on this.

BTW, the going joke is if you've found 'absolutely zero rust', it's simply because you haven't looked hard enough.

[paults1]

I used Wurth under coat that look near the same as the MB factory coating, I also purchased their spray gun to apply it. I think you can also apply it with a stiff brush.