Taxidermy.Net Forum - MUSTY SMELL IN OLD HIDE

Depending on the type of skin and how it was tanned that many years ago, it could be a number of things that are causing the odor.
Any heavy or oily skin that was tanned with old formula tans may be digesting itself over the years. However you would probably be able to see this in the leather. If its not a heavy skin or one that may have been oily, it may have milldew from past environment issues, Old dust or smoking environment would have absorbed into the hair especially if it has fairly hollow hair. A suggestion would be to comb and brush hair carefully to clean as much of the embedded dust as possible. If it is a Furbearer comb only as a brush will ruin the guardhair and underfur construction. If you can see any composition of mildew or surface contanimation on the leather below the fur then you will need to clean it sufficiently to remove what you can without breaking the hair off. Distilled water ,and a small amount of simple green added to denatured alcohol would help in removing contanimation. But you only want to use a very little simple green as you wouldn't want to add additional smell to try covering it up with another one. It would take some effort but if the skin has sentimental value it would be worth the effort. Start by working on an area about a square foot in size and staying with that area till you feel its clean, Mark the borders of each square foot completed with white out dabbed on the fur at edges of these areas. When finished with an area Gently use compressed air and comb to dry the skin surface. experiment with the amount of alcohol and water combination until you have a liquid that works well. alcohol will help absorb and evaporate water you don't want to allow the surface to become too saturated. Warm air and a fan will help further the drying process overnight.
Here up north you find a lot of big moose hides that were smoked during tanning process and actually they are quite valuable because of the process.
Deodorizing isn't removing anything and it would need to be repeater routinely