• Question: How does glue not stick to the inside of the bottle?

    Asked by to Ian, Mathew, Naomi on 26 Jun 2014. This question was also asked by .
    • Photo: Ian Stephenson

      Ian Stephenson answered on 26 Jun 2014:

      Normal glue is some kind of bonding agent (sticky stuff) mixed with a solvent (stuff which stops it sticking).

      In the bottle the solvent keeps the bonding agent from setting, but when you pour it out it gets exposed to the air. They solvent typically evaporates really easily when exposed to air, so when you use the glue it “sets” when the solvent has all left. Thats why glue takes time to set (the solvent is leaving), and why it usually smells funny (thats the solvent you’re smelling).

      Inside the bottle, some of the solvent will evaporate, but there’s not much air, so only a small amount can escape – provided you put the top back on the bottle!

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