There are several advantages to the tube acrylics that are fun to experiment with that aren't available with bottled acrylics.
Gel mediums are a clear acrylic substance with the thickness of hair gel. They come in a variety of thicknesses and the purpose is to change the consistancy or appearance of acrylic paint.
Depending on the type of medium it alters the consistency of paint, adds sheen, reduces gloss can add a transparent coat, prime a canvas or protect a painting and bind paint. Artists use
gloss medium to highlight specific elements of a painting such as the edges of clouds.
Gel mediums are available in gloss, matte, and semi-gloss. These mediums are also used successfully in cocllage, decoupage and transfers.
The gels come in self leveling which is used for gloss and, soft gel which is used for glazing and transparency effects. Regular gel extends paint and heavy gel increases the pody of paint and holds peaks. Extra heavy gel is ideal for impasto. The matte finish also retains brushstrokes well.
Fine pumice gel adds texture, coarse and extra course pumice create a granular surface and the glass bead gel contains actual glass beads and give a painting luminescent quality. Clear granular gel adds a textured, translucent area.
One of the important features of gel mediums is that they are archival so they will not discolor or loose adhering properties over time.
Since a lot of my painting is now being done on canvas and I am using primarily the tube acrylics for this surface I have been using both the matte and gloss gel as a protective coat when I finish...which gives the acrylics more of a brilliance and depth which I am liking. You can also mix the gloss and matte for a semi-gloss which is my favorite.
The above mediums are found in both Liquitex and Matisse....