Hi David, I have been casting labels and Chiyogami paper for a few years now and have sorted out the problems I had at the start. I will take you through what I do and you can take it or leave as you please.
To start with, I have to say that I use PR and an inkjet printer, but the principles should be the same. Also, I do not have a pressure pot and the results are fine. I have tried using Avery label paper but I just cannot get on with it, though many people use it. I use high definition paper to suit my Canon printer. I first paint the tube white with car primer paint - this helps the white parts of the label stay white and also gives a good surface to take the glue I use. When the paint is dry, I stick the label on with tacky glue, which can be found in craft supply shops. When the glue is dry, I give it 2 coats of clear PVA glue, again found in craft supply shops, allowing drying time between coats, making sure to work it into the label ends. This is important to avoid resin soaking into the ends and spoiling it. I used to use Mod Podge, which worked well, but the PVA is cheaper!
I think the trouble you are having with white parts discolouring is probably due to the brass tube showing through if the resin soaks into the paper. Remember, the white parts are just the paper itself.
Another thing I do that might not be necessary, is after the casting is trimmed to length I dribble some thin CA onto the exposed ends of the label, wiping it off before it dries. Just to prevent water soaking in, as I wet sand to final size.
That's really it. Any questions, just ask.
Harry
