(This is a direct replacement for Triafol)
Electron Microscopic Specimen Preparation Triafol Replicas:
The Triafol technique is a method for making electron microscopic specimens which corresponds to a great extent to the indirect replica method described by Mahl and Konig. Triafol foil (trade name for acetobutyrate foil) Instead of varnish composed of pyroxylin and amyl acetate is used for taking replicas. The preparation time is thereby greatly reduced while the quality of the substances remains the same. Whereas pyroxylin-amylacetate (zaponlac) replicas may not be removed from the base until they have dried for 10 hours, the fast drying Triafol foils may be removed after only 3 to 5 minutes, without having to expect deformations. The entire preparation process from taking the replica to finished specimen requires approximately two hours.
Mode of Operation:
For reproducing smooth and moderately rough surfaces, foil of 0.04 mm thickness is suitable while 0.1 mm Triafol foil should be used for rougher surfaces. Depending on the size of the surface to be replicated, cut small foil pieces and clean carefully with a soft brush removing any adhering particles. Wet the preparation spot, which is to be replicated, with a few drops of acetone (spray from a fine glass capillary tube). If too much solvent is used, there is the danger that the thin foil expands too much and then tears when it is removed. Before the solvent can evaporate apply the Triafol foil to the specimen surface with as little pressure as possible and wet the foil with acetone. Always use the dull side of the foil for taking replicas. The dried Triafol replica can be removed from the base after 3 to 5 minutes.
Coat the foil with a thin metal or metal oxide layer in an evaporation unit. After oblique shadowing (angle 15 to 25 degrees for smooth objects, 30 to 45 degrees for rough objects) and application of a very thin vertical vapourization layer, coat the foil on the vaporised side with a paraffin film of approximately 0.3 mm thickness in order to render the thin vaporisation layer more solid. This layer can easily tear during the subsequent solution process because the lacquer expands greatly when it enters into contact with a solvent. When the molten paraffin (melting point approximately 52 to 53 degrees C) is applied from an open glass tube, make sure that no paraffin is applied to the back of the foil.
For the dissolving processes described below, make sure that there is absolute freedom from vibrations because the slightest oscillation causes tearing of the thin replica foils and renders the replica useless due to the formation of folds. Place the matrix cautiously into a methyl acetate bath saturated with paraffin (paraffin side upwards) until the violet colour of the Triafol foil has disappeared.
Remove the matrices after 20 minutes with a glass siphon and rinse again for 5 to 10 minutes in a second fresh methyl acetate bath. Then, dry matrices In a dust-free place on filter paper, with the shadowing layer upwards and the paraffin layer downwards. Then, cut specimens with a razor blade into small squares having an edge length of approximately 2 mm; place these (vapourisation layer downwards) on the surface of clean electron microscopic specimen carriers (specimen diaphragms or grids), and weigh them by placing a small piece of brass wire mesh (0.3 mm wire, 0.6 mm mesh width, size 2 mm x 2 mm) on them.
Place the specimen diaphragms, which have been weighed in this manner, in a bath with heated toluene p. A. with forceps for removing the paraffin. Leave them in the toluene bath until the paraffin has been removed completely (approximately 10 minutes). Remove all paraffin traces in a second toluene bath.
Take out specimen carrier cautiously and dry carefully. The replica foil may easily tear if the liquid which is contained in that diaphragm cone is sucked out suddenly.
Therefore, place the diaphragms on the filter paper first with one edge only. When the specimens are dry, the wire meshes can be thrown off easily.
Contaminated or damaged specimens can usually be eliminated by light microscopic control.