Incomplete infiltration results in which block characteristics?

• A. Moist block, soft
• B. Hard block, dry
• C. Brittle block, crumbly
• D. Clear block, uniform

Answer: (A)

Incomplete infiltration means paraffin hasn’t fully penetrated the tissue, leaving moisture trapped inside. That moisture makes the embedded block feel moist and soft, rather than firm, which is exactly what you’d expect when the wax hasn’t replaced all the water and air spaces. When sectioning, a moist, soft block tends to be difficult to cut cleanly and can cause tearing or smearing of the tissue.

So the best choice describes a block that is moist and soft. In contrast, a hard, dry block would suggest excessive dehydration or insufficient wax penetration, a brittle or crumbly block points to other processing issues such as improper wax temperature or cooling, and a clear, uniform block indicates proper infiltration.