Cellulose Acetate (Pack of 20)

Cellulose acetate sheets and tape provide a quick and convenient means of replicating surfaces, particularly from large objects which cannot be sectioned. They soften in acetone, allowing them to be applied to surfaces which have been pre-wetted with acetone, then the replica can be stripped when dry. For fine detail, positive replicas can be made by coating the surface with carbon and then dissolving away the acetate sheet with acetone.

The carbon replicas can then be examined in the TEM. Alternatively, the replicated surface can be covered with a conductive coating and examined by SEM as a negative replica. Supplied in packs of 20 sheets, or as tape in a convenient dispenser.

This material is cellulose acetate of a thickness 35 micron. It is soluble in acetone. A piece of the replica material of a size suitable to cover the area to be replicated is cut from thesheet. A drop or two of acetone is placed on to the specimen surface and the replica filmimmediately applied (allowing surface tension forces to pull it down; no pressure is required).

The film should be left to dry for about 10 minutes when it will separate very easily from any reasonably flat surface.

It can then be stretched between two pieces of cellulose tape, structure side outwards, wrapped round a microscope slide, and placed in a vacuum coating unit for shadowing and carbon evaporation.

The required area is cut out from the film, and laid, carbon side up, on to microscope grids on a wire mesh standing in a dish of acetone, with the acetone just touching the bottom of the mesh.

After one hour, remove the grids from the mesh and wash individually in acetone before drying.