Making Ceiling plaster is not something
that should be done by an amateur, this is something needs to be followed
specifically in the directions, and all precautions need to be used
for everyoneâ??s safety. If you have no experience with making ceiling
plaster, it is suggested, you wait and have a professional assist you.
Once the plaster is made, it will not be water resistant, and this cannot
be done overnight. Once made use immediately than discard any unused
product.  

Now that you have made the decision
to go forward with making the ceiling plaster, and you have y our protective
gear on, such as protective eye wear, and rubber or latex gloves, be
sure you have an open and well insulated area to mix your cement. Take
a large bucket, or tub whatever it is you will be mixing in, place over
a spread of newspapers, or something to protect your surface with, than
you need to mix roughly, one 10 pound bag of powdered gypsum, and one
pound container powdered wall sizing. Put these inside your bucket or
metal container, please be sure you are wearing a protective mask and
are doing this is an open and well insulated area when using powered
substances. This is very dangerous to your health! Now add one tsp powdered
alum. Mix these with a wooden paint stick, or wooden spoon of some form,
stirring and mixing well. Begin adding your water a small amount at
a time, depending on how much you need. Remain stirring till you have
a lump, yet smooth cement type substance, stir thorough out your process
so this does not dry and harden inside your bucket. DO NOT ADD TOO MUCH
WATER. Diluting the mixture will ruin your plaster.  Use your best
judgment.  Once it has been mixed properly you are ready to apply
the ceiling cement to your ceiling project. Please do so with caution.
When finished store in a bakery or cloth bag. Any container made of
plastic may crack and cause mess.  Seal up and store in a dark
cool place, label your item as ceiling plaster, and keep away from all
children and animals.