I have a Harbor Freight heat gun with 2 heat settings and it seems to work well on low just hold it 5 to 6 inches from the capsule and rotate the bottle. Most HF stuff is junk but for $8 on sale what do I have to lose, some time you get lucky and find something good from them.
If you use a ink jet printer after you print the labels you can spray them with a rattle can of lacquer, that will seal it. It comes in either satin or gloss finish. You can get it at Home Depot or Lowes, Deft is the brand HD carries.