Design Challenge Keeping Time

I am showing how to make a hourglass using water and oil instead of sand. This was inspired by The Oakland Toy Lab who made a instructable called Liquid Hourglass.

• Two 16.9 FL OZ Water Bottles
• One or Two Straws
• Duck Tape
• 2 1/3 Cups of Water
• 2 1/3 Cups of Oil (I used Canola Oil)
• Hot glue
• Scissors

Optional Supplies :

• Precision Knifes
• Funnel
• Ruler
• Marker or Sharpie
• Food Coloring or anything to color water

Just take off the label and if you want dry the inside of the bottle but that is optional

Taking both caps from the water bottles you will heat up the glue gun the glue both caps together. Then after the glue is dry you take the duck tape and tape around the caps to secure that they wont fall apart and to make sure their wont be leakage. Something I did was I did three layers of duck tape to make it more secure but you can do as many as you thing will be good.

Taking a small precision knife I made two holes going through the caps I didn't measure the hole or anything I just made them big enough so the straw will be able to fit through. But if you want you can draw out the circles then cut then out.

Using a ruler I measured 2 inches of the straw then made a line with a sharpie. After I just cut on the line using scissors. Since I still had enough of the straw left I used the same straw following the same procedure. Incase you have a bendy straw I used the bottom part of the straw.

The way the straws are going to be placed in the cap on will stick up while the other sticks down. If still confused look at the picture to see. After then you just glue around where the straw ends. Make sure the straw wont fall through the hole.

I filled a cup with 2 1/3 cups of water but to make things easier you can use a measuring cup. Then using the funnel I filled one the empty bottles with water. And did the same with the other empty bottle but I filled that one with oil instead.

To make it more interesting I decided to color the water using food coloring. Incase you don't have food coloring you can grab paint and a stick and just stir the paint in the water till it gets to the color you want.

This is the last step but it's can go wrong easily. What you do is place the cap on the bottle with oil and closed it the same way you will do when closing a plastic water bottle. Then to your sink incase water or oil spills. Place the water filled bottle at an angle and quickly flip the oil bottle on the top of the water bottle and close it quickly. If you are quick enough nothing would have spilled. Also double check to make sure both sides are closed completely. What I did to make sure their wont be any leakage was wrap the caps again with two layers of duck tape. But that is optional.

Now that you are done you can flip it over and watch how the bubbles of water go down while bubbles of oil go up. This should last for 20 minutes so it can be used as a 20 minute timer.