Petrol Tank Sealant?

[XS850]

Hi All

Coming towards the end of my CB400f rebuild and time to look at the petrol tank - scabby in places with small rust spots coming through the paint (Light Ruby Red). So, stripped all the paint off plus an enormous amount of surface filler only to find a hardened “black” coloured skin (epoxy?) over the whole surface - looks to me like tank lining but on the outside! Anyone come across this before?
I suspect if I remove it I’ll find lots of pinholes - it wasn’t leaking before but to me it’s been “bodged” so reluctant to leave as is!
Anyone got an early CB400F (75) going spare - colour & paint condition irrelevant
Cheers - Bruce

[Rayzerman]

How is the tank condition on the inside?  The coating may have been an epoxy primer, which likely is best not stripped off.  I wouldn't do anything without first doing a de-rust with EvapORust and verifying no leaks from the inside out.  If none and tank cleans up inside OK, then I'd go ahead and tackle the outside..... filler if needed, a good sanding with say 320 grit and a self-etching primer.

[XS850]

Many thanks to Ted for a replacement tank - stripping old paint off now and it’s much better than the one I started with (welded panel underneath, covered in epoxy, lots of dents and dings) - this one will keep to my standards better I think!!

Bruce