Flame polishing

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Flame polishing, also called fire polishing, smooths surfaces by briefly melting them with a flame. When the surface melts, surface tension evenizes the surface, giving a smooth finish. The result depends on the operator’s skill. When done well, flame polishing yields the clearest finish, especially on acrylic, and it’s best for flat external surfaces.

This method is widely used in acrylic fabrication because it’s faster than abrasive methods. An oxyhydrogen torch is often used, since its flame is less likely to contaminate the plastic. Flame polishing is also essential for making glass pipettes used in patch-clamp voltage-clamp experiments.

Different machines and flame sources are used. Gases include natural gas, propane, oxygen, and hydrogen. A specialized unit called a hydro flame generates the flame from distilled water and electricity. The flame’s size, shape, and chemistry vary with the material being polished.