As we are using acrylics in March you may find that acrylic matt medium is mentioned and added to the paint. There are also acrylic gels available. This video explains the difference between the two and how to use them. We have been using acrylic Matt Medium in class for a while now.
My tip: For your next class prepare your paper with a coat of either an acrylic gel or acrylic medium (add a small amount of water and paint straight onto your paper) allow to dry. This is now ready to paint on. Notice how different it is to just painting on paper! You have now changed the paper with the acrylic medium or gel.
1. Add a Gel to extend the paint (make it flow a little easier) but also to give peaks and troughs - a thicker way of applying paint. Think palette knife
2. Add a medium, i.e. matt medium to make paint flow, also can make the paint transparent
3. Stay away from Acrylic VARNISH - please check and this is not any of the above so not needed :)