Re: Repair broken plaster sculpture
if the plaster is completely dry, white glue works well. Just coat each side of the crack with a thin coat and let dry (to seal the plaster), then re-coat and assemble. Masking tape should work to hold the pieces together.
if the plaster is still damp, white glue won't work. You could then use plaster to "glue" it back together, but this can be messy and difficult if you are trying to get a perfect fit (but better if you are filling gaps). Wet the plaster pieces thoroughly (but not dripping wet) before applying fresh plaster (otherwise the dry plaster will rob the new plaster of its water before it sets).