Skeleton cleaning and preparation
Most of the animals processed are still fresh, and therefore the flesh can be removed with ease and without the discomfort of bad odours. The general process for a medium sized animal (jackal, fox, and caracal) may be summarised as follows:
First step: Slaughter animal and remove skin and intestines. I usually bury the latter somewhere in our garden. (Francois nowadays also tans the skins using a very rudimentary method - more info about hide treatment elsewhere).
Removal of excess meat: Remove most of the meat (also destined for burial). This is the most important part of the process. The more thorough this is done, the less work further down the line. It is important to take special care NOT to remove the tendons during this step. The tendons are literally your friend when it comes to skeleton assembly – especially with vertebra assembly.
Preparation for degreasing: Drill two holes at top and bottom of the femur and humerus. This is done to allow bone marrow to escape from the bone cavity. Failing to remove bone marrow will result in bones turning yellow as fat will leach through the bone causing discolouration.
Maceration: Place carcass in water/soap mixture. I use normal dish-washing liquid and plastic drums with lids to limit bad odours. The lids should be perforated (one or two 1/2inch holes should suffice) to allow oxygen to enter the container. This is important as it allows optimal bacterial activity. The dish-washing liquid assists in degreasing the bones while maceration is in process.
Degreasing: After two weeks (2 weeks in summer; in winter closer to 4 weeks), remove stinky water and pour a 50% ammonia solution into container. Leave for 2 – 3 weeks. Interesting fact: The “stinky” water may be used to inoculate a compost heap with bacteria and accelerate the composting of garden material.
Removing ammonia: Remove the ammonia solution and soak bones in clean water for up to 3 days. This is done to dilute and rinse excess ammonia.
Cleaning of bones: Remove carcass from container and start the tedious process of removing rotten meat. This is done with a simple pocket knife (I find small knives work better). The ammonia takes away most of the bad odours and the meat attached to the bones should be fairly soft and easy to remove. A small brush or toothbrush may also be used to remove excess flesh in the hard-to-get-to corners and cavities. It is important not to remove all the tendons. This part of the process is the most time-consuming, tiring and will leave you with smelly hands.
Bleaching: After cleaning, the remains are placed in a 10% hydrogen peroxide solution for 24 hours. The bones are then removed and placed in the sun to dry. Important: Chlorine-based bleach should be avoided as free chlorine will attack the calcium in the bones resulting in flaking and degradation.
Assembly: This is the fun part of the project and a bit like building a jigsaw puzzle. Superglue and epoxy plays a vital role in the assembly of the skeleton. I prefer using wooden rods to strengthen the vertebra column instead of wire. The wooden rod may be steamed and bent in the required position, rendering the final product with a specific posture. Once the skeleton is assembled and mounted, the final task is to remove the tendons and re-attach bones with glue where the tendon previously fulfilled this task. However, this last step is determined by the objective of a project. A ligament skeleton has specific advantages when considering educational objectives, e.g. the study of motion.
Polishing: A polishing tool (e.g. Dremel) is used to do final touch-up and to remove unsightly matter. I prefer not to treat the bone with a varnish or lacquer, but this is a personal preference.
A last note: The technique described above is a general one and provides a framework for the processing of medium sized mammals. The processing of birds, fish and small-sized mammals require specific adjustments and additional processing steps.
One of the advantages of the method described above as opposed to using dermestid beetles or burying the carcass in a compost heap, is that the cartilage sections of the skeleton, e.g. vertebra discs and thoracic cage (a bony but cartilaginous structure in front of the rib cage)stays intact; as does the tendon connections of the ribs to the vertebra.
It is important to note that with road kills, different parts of the bones and/or skull may be shattered. It is often a challenge to slot the various bone fragments into their correct spots and might take some time to complete. However, it is somehow surprisingly gratifying when the shattered skull of a badger is finally transformed to its former glory - almost as if the ungracious death of the animal is corrected and some lost glory restored.