Blisters Possible Fault Cause Solution 1st stage burnout hold too short
Ensure 1st stage burnout hold time at 220¨¬C is 4.5 hours. If problem still occurs, increase hold to 5.5 hours.
Flasks de-wax at too high a temperature
Do NOT exceed 240¨¬C in the 1st-stage burnout (see burnout section).
Flasks placed in furnace too soon after investing
Do NOT burn out before min. 1 hour after investing.
Flask placed too close to or touching elements
Leave a minimum of 50mm gap between flasks and elements.