I have a bottle of Liquitex Pourable Medium in my stash. I don't know why or when I bought this, but thought I would use it as a clear glossy topcoat on a piece of art. Here is the piece I am using, which is a gelli print mounted on black canvas.
I put my canvas on painter's pyramids so I could see and take care of any drips that go down the sides. I used a paint brush to apply the medium to the sides. I then poured the medium over the top. I was disappointed because the medium did not self-level, but I think this is because it is old and has gotten a little thick over time. I had to add more dots of medium wherever the coat was thin since it didn't level out by itself. Since it was thicker, it stayed on the top and did not drip down the sides much (which I just brushed smooth).
Here it is with the coat of medium. The top edge toward the left looked kind of jagged when it dried. I also hadn't made sure my art piece was level so the medium was a bit thicker in this corner. (Next time I will watch Youtube videos before trying something instead of afterwards. I would have seen that leveling it was important). I tried to fill in this jagged edge after it dried but it didn't look very good, so I ended up adding another full coat to it to fix this.
I still have a 1/2 bottle of this medium. After watching Youtube videos, I am excited to try mixing this with paint and pouring it over canvas. I will need to buy another bottle to try this other technique, so I can have multiple colors to pour. This medium is expensive, about $14 for 8oz. so I think it's a bit expensive to use it for a top coat. But it did dry to a nice finish. I think the coat may have leveled out better, but also drip down the sides more, if my bottle was new.