Theory in practice

Fossil preparation

        It goes without saying that many beginning collectors have found a fossil that needs extracting, cleaning or preparation. Seldom does it happen that specimens are prepared by the mother nature itself, and so do not require any work to be done. A professional preparation requires not only a specialistic equipment but first of all a lot of knowledge, time and manual skills. However, we might want to prepare the findings ourselves. The basic issue is to choose the right tools for the right type of rock. You should take into account a potential difference between the hardness of the specimen and the rock it is embedded in. Fossils extracted from the ground, loam or clay just need to be washed with soap and water, and wiped with a cloth if needed. Limestone fossils generally need to have the outermost layer removed. Chisels come in handy in this task, but you might also substitute one with a hard screwdriver, a hand engraving machine, or a mini grinder with a wide range of milling cutters and brushes. Fossils embedded in various types of slates and chalk are especially prone to damage during preparation. The latter matrix sometimes requires a scraper, a paintbrush, a soft brush and a sharp object, e.g. a pin. The hardest to prepare are the specimen embedded in flint or ironstone; however, if we succeed in cracking the rock in the right place, it might turn out that the fossil is very well preserved. Aside from the mechanical preparation, there is are also chemical techniques, but they require a higher level of initiation, and are dangerous in a certain way. We do not recommend it as a first-choice method. The only cheap and easy chemical technique to prepare a fossil using a vinegar solution bath. If the fossil is harder than the matrix, you might want to boil it in the vinegar solution an hour or so. One should bear in mind that ammonite shells are also made of chalk, so if we overdo the solution or the time we might lose the rose along with the fossil.

Below we present you a few tools and utensils helpful in preparation:

de40a1b24b0eb9f68c37bfa39988 Bench grinder helps remove the excessive amount of rock, though it is not recommended in precisive work.
d6cae99b9742f6f5513e7ed1b1b8a4b36215350a85c7e69bce5fca7f373d0d31 Mini grinders are irreplaceable when it comes to preparation. When choosing the right model we should pay attention to its power, rotation frequency and regulation. Thanks to it we will be able to work on different types of rocks with a proper precision.
62h613 The choice of mini grinder accessories is also essential. Apart from milling cuters, steel and brass brushes of different hardness level are also used.
3bb74bbf4217a668062849b567b7 Impact graving machine precisely removes the excess of matrix from the specimen. The knob on top allows us to regulate the point’s hitting frequency.
full Scrapers, chisels, burins, slot drive screwdrivers are useful during the initial stages of preparation, e.g. extraction the specimen from the matrix.

Ammonite cleaned with a mini grinder with a steel brush.
Belemnite rostrum and fauna from Wrzosowa cleaned with a mini grinder with a brass brush.