Water Level Controls and Devices. A water column is used on a steam boiler to reduce the turbulence and fluctuation of the water level so the gage glass can provide a steady, accurate water level reading. The use of a water column is not mandatory.
Preparation. Verify the paint is completely dry. Never use varnish to seal acrylic paint if it is even slightly wet. Dust the surface of the dry paint gently with a clean cotton rag or paper towel. Rinse a jar or cup with water to remove any dust particles. Read the label on your varnish to find the correct water-to-varnish ratio. Mix the varnish with water in the jar or cup.
Because acrylic paint is already naturally glossy, matte medium is handy when a more subtle, non-reflective finish is needed. You can also mix gloss and matte mediums together in equal parts to achieve a kind of semi-gloss. Few Parting Tips. 1  Always mix in the medium after you've mixed the colors together. 2  Don't use oil mediums with acrylics because they aren't compatible. 3  Some medium products claim that they can also be used to varnish your paintings. 4  I recommend you use a removable varnish as a final top coat instead of a medium.