Weird Science: Calling All Chemists

[Kennah]

I'm the volunteer Science Club coordinator at my kids' elementary school. Yesterday, we made slime using glue and borax to see and handle a polymer. I had been wanting to vary the experiment somewhat since we've now done slime almost every year for several years--it's relatively easy and fun so it's a win.

I did a little reading, and it seemed that wood glue might produce slime with slightly different properties. I made a batch in advance, and it seemed slightly "bouncier" than white glue slime. So I had two groups make wood glue slime and three groups make white glue slime.

Mission accomplished!

Wood glue slime and white glue slime definitely exhibit some different properties--most notably that wood glue slime seems to take longer for the borax and glue to react and form into a slime. The result was that wood glue slime is quite a bit messier and stickier, at least at first. It was something of a moment of dread as I had visions of parents with torches and pitchforks.

As the kids handled it, the reaction seemed to complete and it wasn't quite as sticky; however, wood glue slime seems to act more like a liquid than does white glue slime. In any event, the kids had a lot of fun and I got a lot of questions about getting a clean paper copy of the recipe to take home. Wood glue slime can get very "attached" to paper.

In the interest of pushing the bounds of science, has anyone ever made slime using other types of glue?

Gorilla glue is the one candidate sticking in my head (no pun intended) to try.

Am I venturing into dangerous waters?

[slackmaster]

1. Good Lord, I hope the kids aren't eating that stuff

Gorilla glue is pretty dangerous to handle. It's cyanoacrylate based so it sticks to skin and other tissue hard, plus it foams up vigorously and massively when it comes into contact with even a tiny amount of water.

Be careful.

[Maine_Nurse]

2. Trust me...

Just say NO to Gorilla Glue or any polyurethane-based product. The parents might actually break out the pitchforks.

You might want to play with different brands of regular wood glue though. I believe they differ somewhat in their resin types and ratios. Might make a difference.

[Igel]

3. "Dangerous waters"--also no pun intended.

Gorilla glue uses isocyanates to produce polyurethane. Gorilla glue in "drying" is really just crosslinking of the polymer chains, forming polyurethane, a chemical reaction. Water, all by itself, reacts with the stuff to form the polymer. It won't form slime; it'll just set up. The stuff is toxic, nasty, and dangerous. Kids shouldn't be around Gorilla Glue. The other reactant is water. It produces CO2, which is why it foams. Mixing Gorilla glue and water in the kinds of quantities you must be talking about would be a dangerous mess.

White glue has polyvinyl acetate in it. So do some wood glues. (Polyvinyl acetate = PVA) When PVA glues dry they really just dry; the polymers already in the glue just have all the water go away so that they form the plastic. There's no chemical reaction in that.

Making slime involves a chemical reaction, the borates reacting with the polyvinyl acetate in the glues to crosslink the vinyl chains. Really, in the same kind of way (with all the details different) as the formation of the polyurethane. The difference in the wood and white glues will involve either different pHs or "contaminants" (from the point of view of the primary reaction, which is ). Add a few drops of ammonia and see if the wood glue/borax slime goes any faster.

Note that a lot of carpenter's glues use casein. Perhaps in combination with the PVA. Dunno enough about casein to say if it's likely to react with the borax. Sort of doubt it, but it's not a strong doubt.

[TheMadMonk]

4. Water solubility I think is what you need to think.

Messy science is the funnest science whatever your age, but soap and water must be watchwords at the end of the day in a school.


You might also consider cornstarch and water, which I'm sure you're aware behaves like a solid when handled vigorously, but pours like a fluid. Mythbusters did an episode where they walked and even danced on the stuff.

They did it with a deep tub of the stuff so Adam could telegenically sink up to his neck. For a schoolyard something different would be in order. Depending on your connections you might be able to get a few hundred kilos of condemned cornstarch from a mill and build a 10m long running track filled to a depth of 10 cm or so.

Next best thing to walking on fire, and safe enough for a kindergartener.

Make a day of it. A science experiment the whole school can participate in.

[Duwamish]

5. My nephews used to love playing with cornstarch and water.

It really sparked their curiosity and got them away from the video games for a while. But what a mess they made! Good old Auntie cleaned it up because they wanted to play with their Legos. What ever it takes to encourage creative thinking.

[GaYellowDawg]

6. Try it with the "gel" glue.

The blue Elmer's gel glue. The resulting slime looks different and feels a little different.

[Kennah]

7. I, state my name, ...

... do solemnly swear or affirm that I will NOT give Gorilla Glue to kids.

However, I am going to brew up a batch of gel glue to see what happens.