Did you know that
milk (along with a few other common ingredients) can be used to make
glue?
What fun!
Here's a few
recipes that you can try with your kids next time
Science Fair season rolls around at school:
Simple Milk Glue
Ingredients:
1 Enameled pot (non-metallic)
500ml
skim milk
90ml
vinegar
60ml
water
15ml
baking soda
Method:
1) Heat milk and vinegar slowly, stirring constantly until milk begins to
curdle (separate).
2) Remove from heat and continue stirring until curdling stops.
3) Let the mixture sit until all the
curds (thick white bits) have settled to the bottom.
4) Strain the curds or pour off the liquid (
whey).
5) Place the curds on newspaper or paper towel and allow to dry to a glue-ish consistency.
6) Mix curds, water and baking soda. The vingegar will react with the baking soda. Stir until bubbling stops.
7) Store glue in an
air-tight container.
This glue will keep for a couple of days, but once it starts to smell like
old milk you should probably throw it away. This applies to all these glues.
Simpler Glue
1) Add one cup of milk and 1/3 cup of vinegar to a
mason jar.
2) Let stand until the milk separates.
3) Pour off the liquid (
whey) and discard.
4) Add 1/4 cup of water and 1 tbsp of baking soda.
6) Mix and let stand until bubbling stops.
I haven't tried this glue but it seems much simpler than the recipe above and requires no cooking, which makes it easier and safer for the
kids.
A bit more toxic Glue
Ingredients:
1tbsp
low fat milk powder
80mL water
vinegar
ammonia
Method
1) Mix water and milk powder until dissolved.
2) Add drops of vinegar to mixture and stir until milk curdles.
3) Strain curd and allow to dry.
4) Add drops of ammonia to
curd, stirring until creamy.
Haven't tried this one either; I'm
allergic to ammonia. But it follows the same
principles as the other recipes, except it uses
ammonia as the
base to
neutralize the acidity of the vinegar. I'd stick with vinegar for the kids though.
Why it works
It's all about the Casein
All of the above recipes use
milk as a source of
casein, the active ingredient in this type of glue.
Casein is a sticky
protein composed of complex chains of
amino acids that can be used to make glue as described above or even
biodegradable plastics. But that's
another node.
Sources:
http://www.zetatalk.com/shelter/tshlt21z.htm
http://www.tki.org.nz/r/science/scienceschool/resources/1999/milk_glue.htm
http://chemistry.about.com/cs/howtos/ht/gluefrommilk.htm