plaster 
alginate 
1 part water to 1 part alginate(volume) 
too thick 
add more water
1.5 to 1 final ratio
put my arm in it 
maybe beacuse it is too deep and my hand is open. it is very hard to take my hand out and the mould is brocken. 
my hand is swollen 
add plaster 
We used 500g alginate first but it just up to my wrist(should up to my elbow). So the teacher mixed another 500g alginate and poured into the container. Unfortunatly, I took my hand out when I found it is not enough. Though I immediatly put my hand in again, it was useless. This mistake should be the main reason of brocken fingures(and the fingertips are not clear).
30 minutes for the plaster to set
Is there any material to help demould?
