Q:

How to preserve a servant zombie

In a world that will tolerate necromancy but will not tolerate the theft of bodies or the killing of others, it is possible to create zombie servants, if a necromancer can find a subject lawfully, and I am assuming this is a rare or uncommon occurrence. What would be the best way to preserve the zombie for longevity, but still allow it to perform tasks?
I need the zombie to be as resistant as possible to decomposing or being consumed by insects etc. I am also not looking for a magic spell that will preserve them but some natural or scientific process / body perpetration to do it.
I remember seeing a clip on mummification, the person was covered in salt removing moisture from the body but would this not limit their movements? Also I have heard mention of 'bog bodies' but it was mentioned that their bones dissolve.
These zombies are just like humans, because they were made from them, if tendons are broken they cannot move that piece of their body. So if the zombie is dehydrated then the joints that move the most will eventually crumble. This will result in either the tendon giving way or the joint losing key parts disabling the joint from working correctly.
The zombies need to be in good working condition so they can perform task like walking an angry bee hive into a crowded meeting area, and not drop it, etc.
The question how to keep a reanimated mummified body in good condition, I felt, drew the conclusion that these mummies are to dehydrated and crusty to be sustainable, and would require oiling. But I fail to see how, after their tendons and gaps form in them, they would not be able to continue on without heavy magic influence.
Here is a little how the souls and my necromancy work. Each person has a soul this soul allows the animation of their body. If after death a person has basically left you a deed to their body you can animate this other body. This process requires the linking of your soul to the body creating an animate body bound to your will. If the person had lost an arm and bleed out and you sew the arm back on the zombie would not be able to use this arm, it would be purely decorative.

A:

You could have your Zombie spend all their time not mobile fully submerged in a fomaldehyde based fixative solution:  Wikipedia on Formaldehyde fixtive solution for tissue samples
The biggest downside of this is Zombie Bloggs would become extremely susceptable to fire.  Formaldehyde is severly flammable...   Of course, this could be a useful plot element?

A:

Very likely, this society needs to practice their preservation techniques to find out which one works the best. Since this is a fantasy story, we can't just wait for them to up and tell us.
A dead body is a tasty treat for bacteria (both external and internal) and scavengers. All body preservation methods try to prevent these critters from snacking on the body. Mummies do this by dehydration and removing organs. Bog Men are made by making the bodies a very inhospitable environment for the things that can get to the body while transforming the body into leather. These methods take time, and are often dependent on local environmental conditions. I therefore suggest the following, assuming that none of these environments are readily available:

Drain the body of blood as soon as possible. We want to remove as much water from the body, and taking out the blood will deprive a lot of nutrients to invading bacteria.
Remove the digestive track, and as many internal organs as these necromancers will allow, as soon as possible. These bodies will be magically animated, so I'm assuming they won't need to eat things. In any case, the bacteria in there need to be removed, or they'll eat the body from the inside out!
Dry (or "cure") the bodies. Pack it in sand, salt, or anything else, but the less water which remains in the body, the better.
Tan or taw the bodies. Tawing is similar to tanning, but produces a more flexible but less durable product. We need to tan or taw the bodies so the skin becomes durable, and will be less likely to break. Obviously, we do want the skin to retain some flexibility, so these processes shouldn't go to the point that the skin becomes brittle.
Cover the bodies in wax or oil, and do so regularly, so that the bodies have a layer of something to protect themselves from the environment. 

