I have been working with Plastic styrene for years but now have a query.
I usually join it by running the liquid plasticWeld glue down the join and this works fine by literally welding the two pieces together. However, I find myself forced to join a clean piece to a painted piece.
I cannot scrape the painted piece for fear of fracturing the 'Paint job' and spoiling the look. I am aware that it does melt into the paint but I wondered if there was any method to go down to the original plastic base ? There is also the chance of spilling the liquid onto the wrong part of the paint job and spoiling the look.
I find, that when dry, it's possible to snap of the join, taking the painted edge with it. If I use superglue then it's the same effect. The joins do hold in position but are not really very strong when it comes to bumps.
I have to stick plastic letters along the side of a painted hull where they may get knocked off. Here is a picture of someone else's boat to show what I'm after.