From The Spirit Artist - Rev. Rita Berkowitz:
You will feel the strong impression of your face taking on the features or expression of another being. You may feel as if cobwebs are flowing around you face. Avoid rubbing you face with your hands. You must remember that this form of mediumship depends on others in the circle.
A good transfiguration mask of ectoplasm covers the mediumís face and the features of the spirit entity appear. There are times when the mediumís face will fade and the face of the spirit will appear.
When developing this form of mediumship a soft light should be used have a minimal amount of shadow. The other members in the circle should be commenting on what they are seeing. This will build a firm cooperation with the spirit workers.
From Trance and Transfiguration Medium Jay Love's website:
Transfiguration is a form of physical mediumship, which is achieved by an ectoplasmic mask that forms on, or just in front of the mediums face; whereby the persons loved ones press their features into this mallable mask. For all those present in the room to witness. This ectoplasmic mask is created by a combination of the etheric energy of the people in the room witnessing the phenomena combined with the energy of the medium. The spirit world utilises this energy to convert into a semi physical substance. People who have witnessed this type of mediumship feel the immense love and compassion that spirit bring into the room. It is a more intense form of mediumship, mental and physical mediumship combined into one.