Chalkware

A few years back now, my father brought over a box of stuff that my grandmother had given to him for me. The box contained a large assortment of completed crewel and crossstitch which was done by either my grandmother Helen or her sister, Great Aunt Agnes. I still need to go through these items and choose something to have framed. Also in the box was a couple of items I was shocked to have received, chalkware plaques; a red and a yellow rose.
These plaques had hung in my grandparents kitchen for as long as I remember. They are certainly not fine china by any stretch of the imagination, the back of both of them is rough, with no apparent etchings to show where or by whom they were made, and the hook in the back is an archaic piece of metal simply bent into a tear shape and plased into the plaster before drying. I suppose from the back of the piece one may be tempted to believe that they are hand made, but the finish of the rose is too polished to have been made at home as there is definitely some form of a glaze over them both.
The front of the red rose has faired worse than that of the yellow; with many chips of paint missing. I read an article which states that a lot of chalkware was produced during the Depression as it was a cheap alternative to porcelain. It makes sense that these would be around the age of these plaques. I have done some preliminary research on the internet, however, I have been unable to find replicas of these items and have no idea as to their age outside of the fact that they must be atleast the same age as me give or take 5 years.
If anyone has any particular interest in chalkware and can give any details as to how to find out just how old they are I would appreciate it, both of my grandparents are gone now so I have lost any opportunity to ask them.