Not too much to tell, but as I was trying search for rain gutter repair thread it was all fairly scattered. So my idea here is so collect experience about it to make it easier for others in the future.
So feel free to add your experience here!
While repainting my van I sanded down my whole rain gutter to the bare metal as well. I took out the stock sealer using a screwdriver to get the main volumes out, then used a vinyl flooring knife to “clean the corners” and eventually used a wire brush to get to the bare metal.
This was followed by 2 component epoxy primer and Raptor liner layers.
Now I cleaned the surface using bug and tar remover and sealed the gutter off.
I was happy to borrow a pneumatic dispense gun from our lab so that I could dispense the 3M 08308 Heavy Bodied Seam Sealer easier. Once in I used a spatula to “level it”.
And here comes the main info I could find any answer online:
I needed 5 1/2 200ml cartridges of seam sealer to fill the complete rain gutter up again!
And now I can start to put my roof rack back on again :-)