If it was put in when they blow the glass it would stick to the molten material. If they sealed the glass after putting it in, you would see the seal. So how do they do it ?
2007-06-30 10:17:50 · 4 answers · asked by Steven W 3 in Science & Mathematics ➔ Physics
An hourglass is hermetically sealed pure glass to keep the sand dry. It won't flow if it gets wet The wooden frame is just to support it.
To make one, they pour the sand into a cylindrical glass bulb that's closed on the ends except for a small hole. Then they seal the hole by melting the glass locally. Then they heat the circumference of the tube half way up until it softens and slowly pull the two halves apart. This causes the midplane to narrow until there's a small neck.
Glass can be pulled like taffy if it's the right temperature. It's also a good thermal insulator, so you can soften one part, while the bottom where the sand is is cool and hard.
2007-06-30 12:08:56 · answer #1 · answered by Dr. R 7 · 2⤊ 0⤋
They make the glass part. The put one wooden or plastic or metal end on, then the correct amount of sand, then the other end. Not exactly rocket science.
2007-06-30 10:24:10 · answer #2 · answered by Lady Geologist 7 · 1⤊ 3⤋
same way as they get the ship in the, no idea
2007-06-30 10:22:02 · answer #3 · answered by Anonymous · 0⤊ 2⤋
Dunno, but it takes hours.
2007-07-01 15:18:51 · answer #4 · answered by Norrie 7 · 0⤊ 0⤋