taping doorway for epoxy?

[Entropy42]

I just epoxied the floor of my 2nd garage (primer, basecot, topcoat), and I taped (blue 3M painters tape) the garage door threshold to make a clean line, but the epoxy just flowed under the edges of the tape and made a really scraggly looking line.
Two questions:
For my main garage, is there some trick to making the tape work as I intended?
What's the best way to try to clean up the line that I've got? I'm guessing I'll have to very carefully grind away the epoxy on that edge? The threshold that I was taping had been broom finished, so it was pretty rough.

 

[Justin James]

When we had to paint stripes across cinder block we always ran a small bead of caulk along the edge of the tape. Don't leave a bunch of it on the tape, you want to remove most of it with a damp rag. Also try and pick a caulk color that matches either the concrete or the color your putting on the floor.

 

[Huser21]

Tape off with duct tape, Nashua 357 is great, very strong stuff. I use cab o sil to fill my joints and cracks and I also use it on the garage side edge of the tape to seal it off. Pull it before you apply your last coat and re tape the edge with masking tape. On your final roll as you work your way out the door is the only time you roll onto the masking tape and pull it immediately. Perfect line every time.

 

[Kaizen]

try dry brushing it at the tape for a few coats before you roll up to it. Also try lizzard tape and make sure you mush it down to the floor. I do like the caulking idea as well.