Short Note: Vapour Smoothing with Acetone

Vapour smoothing is a chemical post-processing method mainly for ABS (and ASA) FDM parts. Acetone vapour softens the outer surface, which flows slightly and smooths layer lines, then re-hardens.

Procedure

1. Place the part on a stand in a sealed container with a little acetone below.
2. Warm gently to produce vapour (or use a cold method with a soaked tissue).
3. Expose for a short, controlled time (minutes).
4. Remove and let it dry fully.

Advantages and cautions

• Gives glossy, smooth, watertight surface and better layer bonding.
• Over-exposure causes loss of fine detail and dimensional change.
• Acetone is highly flammable and toxic: use in ventilated area, away from flame, with PPE.

Applications

Enclosures, display models, fluidic parts, cosmetic prototypes, casting patterns. PLA is not affected by acetone (use other solvents).

Exam tip

Write the principle, the four-step procedure and the safety note.