What SleepyCreek said! Boro is really tolerant of re-working, but play it safe and bring it up to temperature a bit slower by putting it in the kiln. I've lost two killer marbles recently to shock late in the game (melting in the twisted surface decoration), when I should have been garaging them in between phases in case they had gotten too cold (they had) - it was a sad reminder that yes, boro can shock.
Fortune Cookie say, "When things go wrong, don't go with them!"
Current Glass-Melting Apparatus:
GTT Lynx powered by 2 5 LPM Oxycons and
a sexy Barracuda running pure tanked Oxy