I'm having issues with a texture map that I've created for the purpose of a cork. I'm pretty confident I did my nodes correctly, but my biggest problem is this isn't a big item and I don't really want to uv unwrap something that is going to be the size of a quarter. Any tips on why I'm getting distortion on the top of my cylinder ?
Smart UV unwrap might work, but this is how I would do it.
make a seam with Ctrl+E along one of the edges of the cylinder.
Select the circle edges with Alt+click (m1 or m2, however you have it set). Mark that as a seam with Ctrl+E.
Select everything (if your cork is a separate object from the bottle). Press U to unwrap. You should get a rectangle and circle in the UV editor, position these how you want.
As a side note, it looks like you have a lot of fireflies. You may want to follow this article: https://www.blenderguru.com/articles/7-ways-get-rid-fireflies. In short, use a larger light source and use multiple importance sampling (properties/world/settings).
You've nearly got it. This is caused by the UV map really not know what it's doing. There are multiple way to fix this issue, the simplest ones is by simply hitting "Smart UV Unwrap".
You can mark seams in blender as well, which is where the mesh will be cut up when you hit unwrap. In this case, simply select the edge loop encasing the top face and hit CTRL + E. This will be where you can select "Mark seam" to, well, mark it a seam.