The flesh would naturally decay in the air, so to stop decay, the mummy was thoroughly dried out by putting it in crystals of a natural salt called natron. This dried it out in 40 days (scientists call this desiccation). Once it was dried it would not decay.

The brain was then filled with a natural plastic-like substance.

The next stage was annointing with oils to keep the skin supple, while the body was packed with sawdust and linen so that it would keep its shape.