Heat Pen

This instrument, U060, is useful for reducing compression artifacts in semi-thin and ultra-thin plastic resin sections. It obviates problems associated with the use of solvent vapour expansion. Advantages of heat-pen method versus solvent use:

• Better control of heat above the floating sections.
• Compression artifact is more reduced by using heat.
• Accidental touching of the surface or sections is a lesser calamity.
• Toxicity of the solvent vapour is avoided.

Operation:

The power supply is switched on and the hot filament is moved gently just above the sections (about 1 or 2mm). Sections initial expansion is easily observed through the ultra microtome's stereo microscope. Interference colour of the section will generally change by one shade, indicating reduced thickness and compression. Colours change from gold, to silver, to grey. Keep the tip of the filament at least 1mm away from the boat's sealing wax.

Compression reduction:

Studies have shown that unstretched Araldite sections are compressed (shorter than the block face) by 24-25%. Stretching with solvent vapour leaves 5-6% and heat stretching leaves 2-5% compression. Heat stretching is superior in all tested resins.

Physical data:

• Powered by two AA batteries
• The heat pen filament is interchangeable.

Avoid bending the filament tip. Broken filaments may be replaced or can be repaired with a piece of nichrome wire or thin platinum wire. Crimp wire or use silver dag.