No.1 on the "I hate doing" list

I have finally started the tedious job of cleaning up the underside of the car.
This is by far the worst job in DIY car restoration and takes forever. First up I soften the underseal/stonechip with thinners which makes the underseal easier to scrape of with a chisel. The remaining layers can then be removed with a cloth soaked in thinner.
I have tried mechanical removal with a wirebrush and a flap-disc but this doesn't work.

I have done most of the boot floor, which has had a lot of welding done at various times, with the new metal not being treated with anything other than stone-chip.. I need to get it as clean as possible before sealing all the joins. I am undecided as to the next coat as ideally the clean metal needs a primer where as the painted bits just need a new layer of stone-chip.. On the spitfire i covered everything in hammerite before applying stone-chip so this is also an option. Before I get this far I need to treat the surface corroded areas with a rust stopper, I think I might try the Bilt Hamber products which have just been introduced in Denmark.