I'm in the process of finishing my new plane.  I'm using blue 3m vinyl tape for masking and, when removing the tape, I'm pulling up a lot of the primer and dope.  The tape is pulling it off all the way to the balsa.  The balsa was finished by sanding to 600grit, then doping with Randolph nitrate dope that was 50/50 with thinner.  I added microballoons to help with filling the grain (I didn't use silkspan).  The temperature was in the upper 40's (That's my basement this time of year).  There there were 4 or 5 coats of the dope/thinner/microballoons.  Could the microballoons or the low temperature have affected the adhesion of the dope to the balsa?   Oh,  the primer is DC540 and I guess the good news is that it adhered well to the dope. 
Thanks for any help,
Rick

The temp. could also be causing you problems. I always warm the shop for an hour or two before I paint in the winter, it makes the paint flow better too.

Derek

 Oh,  the primer is DC540 and I guess the good news is that it adhered well to the dope. 

Best primer I have ever used for planes

I decided to sand it off and start over.  Only took 2hrs to sand off the port side, will finish the starboard tonight.
Rick

Rich, I don't know why you're not using silkspan, but you almost certainly should.  It not only helps to fill the grain, but it puts a hard "skin" onto the balsa that makes it harder to ding and gouge, and it adds considerable overall structural strength, to boot.  If you're trying to fill all the grain then you'll have a lighter plane in the end if you use silkspan, too.

Lighter, stronger, easier, better looking -- what's not to like?

This may be obvious, but pull the tape back over itself and roll it off of the paint, this will limit the area subject to the force of the peeling tape. A hairdryer set to low can help too.