Is embalming necessary for cremation?

No. It is your choice. It may depend on such factors as whether the family selected a service with a public viewing of the body with an open casket, or to enhance the deceased’s appearance for a private family viewing; if the body is going to be transported by air or rail, or because of the length of time prior to the cremation.

(Source: ICCFA FAQs: http://consumer.iccfa.com/faq)