I hadn’t painted over ballpoint pen before and wasn’t sure if it would work.
One advantage of painting over old sketches is that if it gets ruined then it doesn’t matter. More importantly, you can learn something new so it should be seen as a positive if your sketch turns to crap.
If you ruin something and don’t learn from the experience then that is the only time it’s wasteful.
Whilst doing this I found that painting over the solidly blocked in biro actually took off some of the shine of the finish which I personally prefer. And as watercolour is essentially transparent it didn’t cover up anything.
I’ve had a quick flick-through this sketchbook and there’s only a few more candidates for carrying out a “paint-over”. Looking forward to the next.