I don't KNOW but I imagine that it was placed in a glass vial and then the end of the vial was melted and closed off. This would stop a lot of the processes. There would be no further dehydration, Once it had used up the oxygen that was in the vial when it was sealed nearly all decomposition would stop. Nobody knows what is actually in that sealed vial and even if it is blood what "preservatives" might have been added. The various changes could have to do with the varying temperatures or how much light it was exposed to...Or indeed it could be the will of a god that has chosen to communicate with us through a vial of blood. All questions and no certain answers. Some have faith and that is all they need and some will forever be asking how, why, and what...