Liquitex gloss gel medium is a high-viscosity medium that dries to a crystal-clear gloss finish and makes an excellent collage glue. Translucent when wet, it is transparent to translucent when dry, depending on the thickness of the application. I prefer to use gloss medium as my glue as opposed to matte medium because it does not dull the intensity of my colors with matting agents. If you prefer a matte finish, choose a matte or satin varnish for your final two coats of sealer.
I work standing at an easel, and this is another reason why gel medium is a good choice: Gel doesn’t run down the panel and puddle on your easel shelf. It stays where you put it. Also gel is the consistency you need when putting it down on thicker, more resistant papers.
Golden polymer varnish with UVLS (ultraviolet light stabilizers) is a waterborne acrylic polymer varnish that dries to a protective, flexible, dust-resistant surface. I use this product as my final sealant over collage. It is important to note polymer varnishes must be thinned before use. They have been formulated to be thicker than traditional varnishes to maintain an even suspension of matting agents. This ensures more consistency in surface reflectance.
Varnishes are available in a highly reflective gloss and an exceptionally flat matte. The matte varnish will lighten dark value colors.
I prefer something more in the middle, a satin finish. If you want to mix your own version of satin, experiment with a combination of matte and gloss varnishes that meet your personal preference. I combine approximately 80% matte with 20% gloss and dilute that with 20% water.
Liquitex gloss gel medium and Golden polymer varnish with UVLS are two of the products I use regularly. Since I use a lot of each I buy the biggest containers I can.