Freeze-fracture

Freeze-fracture is a natural occurrence leading to processes like erosion of the earths crust or simply deterioration of food via freeze-thaw cycles.

Ambient gases, often water vapor, will condense on the cold surfaces, reacting with them, obscuring detail and further warming the object allowing it to reshape.

Freezing something from liquid or gas phase to a solid allows fracture but has different effects depending on the material involved and how quickly it is frozen.

In the example of water, ice forming slowly results in larger crystals leading to a clear glass like substance.

If frozen quickly as with snow, the crystals are smaller and less organized, scattering light and appearing white.

Changes in the eutectic around the forming crystals is also significant which can be disadvantageous, or used in the case of cooling solder advantageous.

The requirement for freeze-fracture studies may increase with extra-planetary objects having surface temperatures cold enough for elements that are gases on earth to be naturally solid.

Excessive stress results in multiple almost simultaneous fractures, as when shattering a sheet of glass with a hammer.

Better know examples relate to preventing freeze-fracture damage to water supply pipes or engine cooling systems in colder climates.

The sudden release of the energy fractures the entire pane into small less damaging pieces, as with a car windscreen.

[20] Materials and colloid sciences use freeze-fracture techniques to investigate the nature of more complex substances.

Due to the conditions required for the transmission electron microscope at the time the rapidly frozen and fractured virus itself could not be viewed directly.

Instead Steere made a carbon re-enforced chromium replica of the fractured surface based on a procedure devised by others.

[23] Steere overcame the problem of ice crystals forming on the fractured viruses by etching them away as done by others in 1955 prior to making the copy for viewing.

[25] Much cheaper, non-commercial alternatives which did not rely on a microtome or etching to clean the fracture face were later established.

[26] For the Bullivant & Ames method cheaply modified standard coating machines already routinely used in electron microscope laboratories, initially using a Meccano set.

For smaller electron microsopy labs these could be more easily used than a large, specialized, commercial piece of freeze-fracture etch replication equipment.

During the 1960s-1980's it became apparent that the cell's lipid bilayer was shown to split into two halves revealing the interior when fractured under suitable conditions.