You can determine the approximate age of an old bottle just based on its lip. After the glassblower removed the bottle from the mold, he affixed a hot glass lip to the bottles neck.

Do bubbles in glass mean its old?

Bubble: a bubble is a air bubble that became trapped in the glass during the manufacturing process. Bubbles are not considered damage. In fact, bubbles usually add to the appeal of old glass. Glass made after about 1920 does not usually have bubbles.

Does all vaseline glass glow?

Vaseline glass containers are clear, yellow or yellowish-green glass pieces made with 0.1% to 25% uranium dioxide. Many different kinds of glass can have a yellowish-green hue, but the thing that sets Vaseline glass apart from the rest is the fact that it glows green when it is exposed to UV light.