The finish you use is up to you. Use a glossy sealer for a shiny finish. If you distressed the jar, a satin or matte sealer would look better. A spray-on sealer will give you the nicest finish, but you can use the paint-on kind as well.
I also wrote a book featuring mason jar crafts for kids that will be published in April 2015.. Mason Jar Glass Bead Votive. . Finally, as for paints I use craft acrylic paint, chalk paints (my favorites) and spray paint (just for metallic gold & silver).
Painted glass bottles and jars.did this with Jones Jones Leichtman Purvis.It was so fun. Finally! This chalk paint can be used on glass and will not wash off with.
If you would like to paint glass, whether its glassware, a window, a vase or a jar. IdeasDecorating BottlesDecorated BottlesRecycled BottlesJarsBud Vases