When I make a tile, I also make a mold of the original so I can make multiples. I thought I would share with you a little bit about how I produce a plaster mold. First, I construct the original tile.
After the original tile is constructed, I placed it inside a wooden plaster mold form.
This form was built so it could be adjusted to make various sizes of molds depending on the size of your original. (One note, you can see the bird’s profile is the opposite direction in each photo. I made two original tiles and molds of the bird in left and right profile, but forgot to take a picture of each profile. Sorry if I have confused you.) After the joints are sealed with clay so there is no leakage, plaster is poured into the form over tile and left to set until hardened.
Below is the finished mold after the clay form and clay was removed from the plaster mold. The original tile will most likely not be able to be used, but I have the plaster mold to make more. It is now ready to press clay into the negative spaces.
The Art of Sandy Bruckner 
Thank you Sandy – from another Sandy
Thanks for stopping by.
What kind of clay do you use?
This clay was earthenware
Cool
Can you slip pour the tiles rather than press? Or is there too much absorption
It should be just fine. Slip molds are made of plaster as well. Using slip is something I am interested in and is on my “next project” list.
Do you use some sort of release on your original before you pour the plaster?
You would want to put a release (I use petroleum jelly) on the wood mold frame where it would make contact with the plaster. Clay does not stick to plaster, so it is not necessary to put a release on the actual plaster mold. Hope I am explaining myself clearly.
Is the clay mold fired?
Hi, Heather! The mold is made of plaster and is not fired. It will harden when it dries.
Thank you so much ,I am a newby, because you took the time to do this entry I have been given an A+ course.
You are welcome. Congratulations!