This is a bottle with a glass material, and a PNG texture for the label (I know now that PNGs don’t work with Yafray, but this is how I started the whole thing):
Then I learned that TGA files could store transparency, but only if they were saved with a 32 bit depth, so I took the original PNG and saved it again in photoshop. This was the result:
You can see the label now but the bottle isn’t transparent. So I discarded the Photoshop option, searched through google and found this little program called “Image Converter Plus” which turned my PNG into a fully transparent TGA:
Here’s the url if you want to try it: