FDM support material removal requires a heated caustic bath with agitation. Typical removal times range from 4 to 48 hours depending upon the volume of support material on the part prior to placing it into the tank, the of dissolved solids in the solution tank, the pH level in the solution tank and the solution agitation around parts. Leaving parts in too long can result in a degrease in mechanical properties. Because hydroxide needs to diffuse to the parts surface, high dissolved solids inhibits this diffusion and low pH decreases the concentration diffusing.
Using the VCN process to remove the support material eliminates the diffusion step thus lower pH and high dissolved solids is not a problem. The removal time required is generally 5 to 10 times less than the time required in agitated or ultrasonic tanks.