material. A second peel without further etching, a "rip peel", will remove any cell walls that are parallel to the surface, and would otherwise be destroyed when subjected to acid. Details of the modern application of the method can be found in reference (). Even the latest technique does have some disadvantages; most notably, smaller fossils that may lie between cell walls will be washed away with the acid etch, and can only be recovered by a thin section preparation. In order to mount the slides for microscopy, a series of steps are necessary: A glass slide is wetted with acetone, and a fresh layer of acetate is placed upon it. The acetone allows the acetate to 'suck' itself onto the slide, maintaining a good contact by suction. This will later be dissolved, allowing sections of the resin-mounted peel to be cut for transmission electron microscopy. A thin layer of epoxy resin is applied, covering the acetate and spreading onto the slide. This will serve to attach the preparation to the slide once the underlying acetate has been dissolved. A glass plate is greased, and the smooth side of a peel pressed down onto it. The rough side of this peel is covered with warmed (55 °C) epoxy resin, and pressed down onto the previously-prepared slide. After about 45 minutes the glass plate is removed, and the resin is left, warm, to cure. The preparation is washed in acetone and acid to remove any residues, which would otherwise produce optical artefacts when imaged. Specimens recovered by film pull are prone to wrinkling, especially if the surface to be peeled is not perfectly smoothed—if acetone pools, it can cause the acetate to wrinkle. Transfer technique The transfer technique is a technique to stabilise and prepare fossils by partially embedding them in plastic resins (i.e. epoxy or polyester) in order to preserve the position of the preserved fossil once all of the rock matrix is subsequently removed. Notable examples of this technique are fossils preserved in oil shale (such as those from the Messel Pit) or other substrates that will deteriorate under atmospheric conditions, or fossils preserved in acid-soluble carbonates (such as fossils from the Santana Formation). The technique is notable for delivering exquisite preparations of both very high scientific and display value, as the area exposed in this method is protected by the matrix prior to the preparation, while the initially