Maceration is the technique, which removes all meat and tissue from the bones, which are then put together again afterwards.
To remove grease and meat, bones are cooked and cleaned and afterwards they are placed in a bath of enzymes (Bio-Tex for example) so the bones become completely clean. However, there will still be fat inside the bone and the larger the bone, the more fat can drain out. This is still a research topic for conservators.
Another way to clean bones is to put them in a closed container with dermestic beetles (a, museumwise, extremely harmful beetle that eats all meat and tissue). After a few days the bones are eaten completely clean.
A third methode is devellopped at the Zoological Museum in Copenhagen. Here they put – especialy large – bones (like the fin whale from Vejle Fjord) in elephant manoure. Research has shown that this manoure contains a lot of special enzymes, which are very effective to clean bones.
Finally, there could be used a treatment with hydrogen peroxide in order to whiten the bones. This treatment is, however, controversial, because of the damage peroxide causes to the bone surface.
Here below shows a foot of a Wild Boar (unbleached) and a set of Deer legs (bleached).
In many years I have collected bird skulls and, in lesser way, also other animals. They are laying in my little self made museum vitrine.