Shiva Kavacham is divine protective armour of God Shiva. Kavacham or Kavach means protective armour/shield worrier wears on body to protect his life in battlefield That is physical object, one can see it, touch it and so experience it by sense organs. In Hinduism, deity and their gunas (qualities) manifest in many ways, one of them is mantra. Mantra in simplest definition is, speaking, ability of we humans are bestowed with.
Modern Scientists are doing tremendous research on sound and its effect on 5 elements, earth, water, fire, space and air. On one such experiment, sound is used to levitate various objects and move them in three dimensions. We know Cymatics, which gives manifestation of sound as picture or patterns on various surface. In short, Sound do have effect on basic 5 elements and higher levels of consciousness, which, present disciplines of science may not be aware about it.
So, what is kavacham, well, it is divine sequence of words and sentences in sanskrit language which invisibly manifests into protective armour of particular deity. It protects the devotee from all ill and bad around him/her at present or in coming future.
Any person suffering ailments, hurdles in life, stress due to unfavourable circumstances, failures at every step in life, bad luck, unexpected troubles in life, paranormal or unexplainable evil effects in life etc may choose to recite (and so wear) kavacham for his/her protection. There is no fixed time or day for reciting kavacham. For Kavacham recitation one has to choose place and time in such a way that minimal disturbance is there. It is desirable that one knows the meaning of the verses being sung too, if not so, pure faith and unshakable trust on deity will suffice.
Utmost thing required during Kavacham or other prayers of deities, is pure love, affection and trust on them.
Effects of kavacham recitation may not be immediate or obvious. It can be subtle, invisible and sometime incomprehensible too. It could bring your life on track right away or puts you on track in such a way that you reach the safe destination in the journey of life. It basically corrects the course, defeats the evil around and protects you overall.