# What is this foam? **URL:** \ **Category:** Factual Questions\ **Created:** [December 2, 2004, 5:17pm UTC](https://boards.straightdope.com/t/what-is-this-foam/277716 "2004-12-02T17:17:49Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Alectrona](https://avatars.discourse-cdn.com/v4/letter/a/f9ae1b/32.png) [@Alectrona](https://boards.straightdope.com/u/Alectrona)\ **Post date:** [December 2, 2004, 5:17pm UTC](https://boards.straightdope.com/t/what-is-this-foam/277716/1 "2004-12-02T17:17:49Z")
Upon walking home one day, my friend and I came across this hard foamy thing, It is very similar to a meringue but obviously it isn’t because it’s a blob of foam as big as about 3 full rucksacks. It has a similar colour to a meringue, a yellowy cream colour. At the bottom of the foam we could see an alcohol (possibly?) bottle sticking out. The foam is firm 'cause my friend put her foot on it. But if more pressure is applied it would break. So I was wondering, what is this foam, and why would it be at the side of a road?? ---
**Author:** ![Sigene](https://avatars.discourse-cdn.com/v4/letter/s/df788c/32.png) [@Sigene](https://boards.straightdope.com/u/Sigene)\ **Post date:** [December 2, 2004, 6:45pm UTC](https://boards.straightdope.com/t/what-is-this-foam/277716/2 "2004-12-02T18:45:01Z")
Its a common science experiment to pour one particular chemical into another (in a bottle). The reaction produces a polymer and gas (as well as quite a bit of heat) the gas makes the polymer “foamy.” It then “sets up” and hardens. what you found was someone’s science experiment I have completely forgotten the two chemicals involved to make the foam though ---
**Author:** ![WolfpackJeep](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolfpackjeep/32/2921_2.png) [@WolfpackJeep](https://boards.straightdope.com/u/WolfpackJeep)\ **Post date:** [December 2, 2004, 6:46pm UTC](https://boards.straightdope.com/t/what-is-this-foam/277716/3 "2004-12-02T18:46:22Z")
Does it have a slightly slick texture on the outside? It sounds like someone was having some fun with spray-foam insulation, which comes in an aerosol-style can and is typically used to plug holes or seams. It expands and hardens as it dries. ---
**Author:** ![Sigene](https://avatars.discourse-cdn.com/v4/letter/s/df788c/32.png) [@Sigene](https://boards.straightdope.com/u/Sigene)\ **Post date:** [December 2, 2004, 6:46pm UTC](https://boards.straightdope.com/t/what-is-this-foam/277716/4 "2004-12-02T18:46:42Z")
Its a common science experiment to pour one particular chemical into another (in a bottle). The reaction produces a polymer and gas (as well as quite a bit of heat) the gas makes the polymer “foamy.” It then “sets up” and hardens. what you found was someone’s science experiment I have completely forgotten the two chemicals involved to make the foam though ah here it is; first google hit on …science experiment foam [http://www.stevespanglerscience.com/experiment/00000110](http://www.stevespanglerscience.com/experiment/00000110) ---
**Author:** ![Earthling](https://avatars.discourse-cdn.com/v4/letter/e/90db22/32.png) [@Earthling](https://boards.straightdope.com/u/Earthling)\ **Post date:** [December 2, 2004, 6:54pm UTC](https://boards.straightdope.com/t/what-is-this-foam/277716/5 "2004-12-02T18:54:25Z")
Yeah, spray foam insulation is a possibility. Another one (that works on the same principle) would it be foam-in-place packing material, such as [Instapak](http://www.sealedair.com/products/protective/instapak/instapak.html). This material is injected as a liquid foam into a box so that it forms a fitted cushion around a product placed into that box; the foam then dries into a protective shell that’s “hard” but will break under pressure, much like molded styrofoam blocks. The size of these cushions depend on the size of the product they’re protecting, and what you’ve found on the side of the road may just be someone’s discarded trash. The foam itself is light yellow, but would be contained inside a plastic bag (of whatever color) so that it doesn’t get all over the product while still liquid.