Sprayed wood
A braindead person sprayed blue paint on our local sign in the woods. With help of neighbors I took the sign to my workshop to renovate it.
Such untreated, rough wood would take many liters of acetone to wash the paint - with doubtful effect.
Sanding or sand-blasting would be a solution but it would change the surface (rough, with cool hand-tool marks) and probably damage the lettering.
Instead I used chlorine, to remove the top layer of wood and paint. Roughly 0.1 mm was removed but most importantly - uniformly over the whole surface so all marks after axe or power sander were preserved.
Letters got cleaned as much as possible with acetone, then masked and re-painted several times.
Day later me and Pelle took it for hanging back in place. A small operation itself as this sign weights a lot and is hanged high above the ground. We started at 2100 and by 0030 were done - happy and half-eaten by mosquitos.