When I was in the fourth grade, my best friend and I decided to team up for the annual salt dough volcano project. She’d had some experience, having watched her sister build hers the year before, but I was completely unaware of the process of building the volcano and making it erupt. With the excellent instructions given to us by our teacher, and my friend’s previous experience, we walked away with As for the project.
Thirty-three years later, it was my daughter’s turn to make her own volcano, and three years later, my son built his. We are now volcano eruption experts around here. Next year, I will oversee what may be my last volcano construction project, when my youngest child hits fourth grade. Here is a recipe for the salt dough used to make the volcano and instructions for making the volcano erupt, with some tips for making sure that your erupting volcano receives an A+ scattered throughout.
What you’ll need:
A good-sized, sturdy cardboard box
A box cutter, strong scissors, or a heavy-duty craft knife
A 20oz plastic water or soda bottle; we’ve found that VitaminWater bottles work well because of their wider mouth
Poster board (optional)
6 cups all-purpose flour
2 cups salt
4 tablespoons cooking oil
2 cups water
Rocks, dirt, small plastic plants for decoration (optional)
Acrylic craft paint and brush
Liquid dishwashing detergent
1. Cut the box down to create a tray with 2 to 2½ inch sides. Line the bottom of the tray with pieces of the cut-away box for reinforcement.
2. Line the bottom and sides of the tray with aluminum foil.
3. Place the plastic bottle in the center of the tray.
4. If desired, make a volcano-shaped cone with the poster board, fastening it around the neck of the plastic bottle with the top of the bottle forming the mouth of the volcano. (We always skipped this step, but I think it might make the finished product lighter and thus easier to carry.)
5. Make the salt dough: Place all ingredients in large bowl and knead with hands until well-mixed and smooth. Add small amount of water if needed, but be careful—dough that is too “wet” will not stick or stay in place.
6. Mold the salt dough around the plastic bottle (and poster board cone, if you’re using that) to create the volcano.
7. Embed the plastic foliage if you’re using it—you can buy a few branches or sprigs at a craft store and cut them to the size you want. You can also scatter small rocks and dirt over the salt dough for a more authentic look.
8. Let the salt dough dry at least overnight, and preferably longer. This is important—one of my kids didn’t have time to let the dough dry before the project was due, and the wet dough slid off the plastic bottle, creating a big salt dough pancake with a plastic bottle stuck in the middle of it. That one had style points taken off—you’ve been warned.
9. Paint the volcano and let dry.
Now it’s time to make the volcano erupt. Be sure to bring plenty of “lava” ingredients so you can make multiple eruptions:
1. Fill the plastic bottle inside your volcano about half-full of warm water.
2. Add red/orange food coloring.
3. Add 6-10 drops of liquid dishwashing detergent.
4. Add 2 tablespoons of baking soda to the bottle.
5. Using the funnel, slowly add the vinegar—be ready to pull the funnel away when the eruption begins! The mixture of baking soda and vinegar creates carbon dioxide bubbles like the ones inside a real volcano, which push the lava up and out.
One word of warning—depending on how much salt dough you end up using, the final product may be pretty heavy. It may take more than one person to transport the finished product. Our process is designed to help minimize the ooze, but it’s still a pretty messy project, so be prepared! My now 12-year-old would like me to add that if you want a true eruption, skip the baking soda and vinegar and go with Diet Coke and Mentos; this, I fear, would necessitate providing protective ponchos for the rest of the class and could possibly result in points off for too much realism. Your call. Most of all, have fun—this is one of the most anticipated activities at our elementary school, and every fourth-grader looks forward to finally making their own volcano. Have fun making yours!
sabiya dange on December 02, 2013:
its really helpful to those kids....... but I too want to do an experiment for 9th class, so will you plz tell me an idea.....
a on July 29, 2013:
larcaustin46 (author) from Austin, TX on June 01, 2012:
Excellent question, Juliez--the fact is that a lot of the liquid spews out as the baking soda and vinegar react, so there's not as much left as you might think. One of my children's teachers used a length of rubber tubing to siphon off the liquid--you could also use a large drinking straw or, if the volcano mouth is big enough, a turkey baster. Anyone else have any suggestions?
Juliez on June 01, 2012:
Thanks for this "recipe". Curious how you handle this when you have to make the volcano erupt 10 times! Do you empty out your 20 ounce bottle and if so,how?
Eric Cramer from Chicagoland on March 16, 2012:
Great hub! I will have to try this with my two sons. Cool idea!
Eileen Goodall from Buckinghamshire, England on March 16, 2012:
This is such a useful hub for those people with kids and doing science projects, thanks for sharing.