How can I avoid sink holes in my lip balm tubes? What do I do if I have them and it is too late to pour more on top?
Number one, slowly fill the holes, systematically running down the row, then to the next and so on. Pouring too fast will cause air pockets. The material is hot, hot balm is expanded so naturally it is going to shrink when it cools. Pouring slowly along the row allows a little cooling to take place.
When you get done with the last row go back again, row by row and overfill the tubes. Always overfill; remember you can just scrape off the excess and use it again.
If for some reason you have a hole or two that sink holes, take a hair blow drier or a heat gun and just wave over the hole until it melts and levels out. Just don’t melt the plastic, keep the heat gun moving.