From a spiritual perspective, it is best for people to wear any sāttvik (spiritually pure) colour to a funeral. It is preferable to wear lighter colours such as white and pale blue to a funeral as they are more sattvik. Wearing black funeral attire is common in many societies and cultures. However from a spiritual perspective it is most likely to be detrimental to both the family and the person who has passed away.
Since the colour black is tāmasik in nature, it has maximum capacity to attract and transmit negative and distressing frequencies in the environment, i.e. to the extent of 70%. This means, out of all the possible negative vibrations (ghosts included) that there can be in the environment, the colour black can attract up to 70% of them.
Along with this, the surviving relatives who are mourning are generally in a depressed state, also adds to the Raja-Tama frequencies in the environment.
The combination of these two factors makes it conducive for ghosts to possess the mourner through the medium of his black clothing and weakened emotional state. As a result, the overall increase in Raja-Tama also affects the subtle-body of the deceased, increases its distress and impedes its onward journey in the afterlife.
On the other hand, wearing white coloured clothes to a funeral repels the Raja-Tama frequencies and attracts sattvik frequencies. This makes it less conducive for ghosts to possess mourners and give the subtle-body of the deceased any distress.
The continued wearing of black throughout the period of mourning only makes matters worse and also prolongs the state of depression. The negative vibrations of black continue to retard the progress of ancestors and aid the activity of ghosts.
The subtle-bodies of the deceased ancestors, who cannot move forward in their journey in the subtle-realm stay in their family’s homes. They can cause problems for the surviving members of their family. The problems that they cause are a plea for spiritual assistance to help them move on in the afterlife.
Refer to the article – Why would my departed loved ones and my other ancestors want to give me pain?