Mask off with good tape. then brush the bleed-prone edge with clear latex
flat or s/g varnish. what bleeds onto the first color is clear. unmask
promptly. Or, dry-brush the 1st color on the bleeding edge,
then proceed with cutting in the 2nd color directly over your dry-brushed
work. same net result.
"Jeff Ishaq" wrote in message
om...
Hello,

I'm painting a square room, and one wall is to be red; the other walls
should be white. All the walls are spackled. I am having trouble
getting a perfectly straight vertical line in the very corner of the
room, where the red paint of one wall ends, and the white paint of
another wall begins. The slight protrusion of the spackle makes this
transition look very jagged, as it also causes paint to bleed
underneath the masking tape when I try to mask off a nice line.

Is there a trick to getting a nice straight vertical line that
transitions from one color to the other in this situation? Someone
suggested to me 'gum arabic', but I haven't the slightest idea what it
is, or what I might do with it.

Thanks!
-Jeff