Oh gosh, Sjarz, I really have never done anything like that so can't advise you. Are you decorating a wooden plate or a ceramic one? If ceramic, I'd contact one of those "paint your own items" places and see what they advise. For wood, I think most people use a clear glass plate on top of the painted wooden one. Maybe Painting Fool or Kraftymom will have some recomendations for you. Luvs

Unfortunately without firing there is no food safe sealer for decorative painting. Even though acrylics are non-toxic, it is recommended that they do not come in contact with food. But that doesn't mean it can't be done.
Here are a few options...

1) If painting a wood or ceramic plate, you can keep the design to the very outer edges or use them as a charger plate for under a glass one as Luvs mentioned.

2) If painting a clear glass plate, you can REVERSE paint the design on the BACK side of the plate so food can be served on it.

For either the glass or ceramic plate I would recommend using FolkArt Enamels. The pieces can then be 'fired' in your oven to make the paint permanent and washable.

Thanks for the replies, gals. I hadn't thought about only painting the saying around the edge of the plate - doing that would likely eliminate much contact with food.
So, Krafty, if I use those Folk Art Enamels and 'fire' them in my own oven, would you think they would then be food safe?
I love the idea of the glass plate over the wood, but not sure whether I could find what I need there.
Good thoughts from both of you and thanks again.
Suzan J

Firing the FolkArt Enamels does not make them food safe.

Just wanted to say thanks again to both of you for your thoughts on this budding project - had a look around at some clear plates and some glass ones and I think now I can make this with the words painted on the back of the clear one and the glass ones as a base underneath...hopefully it will work out in real life like it is working out in my head...
Thanks again, Krafty and Luvs...
Suzan J