Supplies:
Borax (from the supermarket or a small box from laundromat)
Elmer's Glue-All (White only)
Food Coloring (optional)
Water
One large plastic jar w/screw lid - ala a large peanut butter jar
One plain old cup
Instructions:
Step "1"
Add together;
1/3 cup Elmer's Glue
1/3 cup Water
Food coloring
Shake, stir or mix these ingredients until glue dissolves in water.
Step "2"
Fill an empty cup with 1/3 cup of water
Slowly pour in 2 tablespoons of borax, allow to settle for a minute
Pour off excess water and discard the water
Step "3"
Scrape the wet borax "B" into the jar with mix "A", close lid
Shake like crazy.... oh yeah, shake the jar too
Shake until the slosh, slosh becomes thump, thump
Open and remove the guk, you can scrap extra from the sides
Now play! It may stain things, could get stuck in carpets, who knows?
The Science:
Elmer's glue is copolymer polyvinylalcohol, PVA, a plastic made from oil
Borax is a natural mineral mined from the earth made of boron, sodium, oxygen and water.
Elmer
Elmer: King of the YardWhen you add water to elmer's glue the PVA, being unstable, starts to dissolve in the water.
When you add the wet borax, it is slightly acidic, and it reacts with the PVA to crosslink.
This crosslinking causes the guk to undergo an irreversible gelation reaction much like when an egg boils to become a hard boiled egg. It is safe to handle, but hey! let's not eat it...OK?