An insight from my recent NaOH experience is that to really make things happen you need to mix the stuff up and use it right away while it’s still hot, this will produce the volcano effect visible in @Scrabble ‘s gif from last page and will also heat the seattube to the point where water sizzles when you pour it on the outside of the frame. In my case the bright yellow paint turned orange for a bit but paled to yellow again once it cooled down.
Would be very interested to see the paint cleaned up post sizzle please? I'm tempted to go down this route to remove a firmly stuck seatpost but I really dont want to lose any paint.
An insight from my recent NaOH experience is that to really make things happen you need to mix the stuff up and use it right away while it’s still hot, this will produce the volcano effect visible in @Scrabble ‘s gif from last page and will also heat the seattube to the point where water sizzles when you pour it on the outside of the frame. In my case the bright yellow paint turned orange for a bit but paled to yellow again once it cooled down.