I'm re-gelcoating a boat. I am spraying the field one color, and a
different color boot stripe. I am trying to achieve a very crisp line
between the two colors but it's proving to be a challenge with the
thickness of gelcoat I'm trying to build at approx 20-25 mils.

I'm spray the stripe first taped on the top and bottom edge. Spraying
the dark blue after.

Need a very crisp line between the two. This way after it is sanded,
the two colors will be flat, just like it popped out of the mold.

I'm using 5 layers of 3M's 213 fine line tape, one layer right over
the other both edges of the boottop. Then spraying the gelcoat until
it fills the void.

Pulling the tape while the gelcoat is tacky results in an edge that
sags.

Pulling the tape after it sets up results in a chipped edge.

I am now sanding the over spray off the top layer of tape until the
tape's edge is exposed. This yields a very crisp line, but it is labor
intensive.

Are there any tricks out there?
How do they put stripes in a mold?
I'm trying to achieve perfection cuz good enough is just not good
enough.
Thanks,
Dan