Never tried it with Ultracoat since I only use Monokote. Easy to find out, tho. On an old Ultracoated or Monokoted wing, apply a very light film of straight trim solvent to a small spot. I would use a cotton ball dampened slightly with solvent. Wipe it on the area so that only a thin, almost invisible film is left (the stuff is incredibly reactive with the Monokote adhesive so it only takes a tiny amount). Apply a small piece of Ultracoat to the spot and wait a few seconds. If Trim Solvent is compatible with Ultracoat you won't be able to lift the test piece after a couple of seconds.