I'm no expert here on squirty cream, but I would have to say that you could not consider the cream as a whole to be any of the above. At first glance it may appear to fall into the solid category, but this is only because of the structure that the liquid inside the can holds when heavily aerated. Ruling out solids, you couldn't call it just a gas or just a liquid because it is made up of both, but not to the point of being a molecular compound.

Is it a solid, liquid or gas?

I would say yes.

The squitery foam is what, at least many decades ago, is known as a non-Newtonian fluid - that is a fluid that appears to be a solid untill it is subjected to a threshold stress, after which it flows like a fluid. Such fluids were the subject of my Masters project in Chemical Engineering.

All and none. It is an ill-defined mixture in unstable transition. We used to define solids as holding their shape in defiance of gravity, liquids as conforming their containers’ shapes, and so on, but in practice many materials defy such simple definitions. Even the theoretical boundaries between different classes of material are fuzzy and hedged about with qualifications. For example, a soft solid such as brain tissue sloshes like a liquid when strongly stressed by a punch, say. Roughly speaking, frothed “cream” is an emulsion (sometimes an invert emulsion) of soft-or-liquid fats and gas in syrupy, watery liquid that also might contain stabilising proteins and starchy materials. Droplets, lumplets, and bubbles interfere with the shear and flow of the liquid, thereby stiffening it. A high content of gas reduces the density of the froth, enabling it to stand up in small peaks in defiance of gravity, though it will flow under increased stresses.

So you have a mix of substances of which some are unambiguous gases (Typically nitrogen, nitrous oxide, carbon dioxide, or air), unambiguous liquids (water-solutions and oils) and ambiguous solids, soft fats or starchy pastes. If you wish to pump large quantities, call it liquid; if you form decorative peaks and swirls, call it solid. Just don’t take the terms seriously as essentialist or definitive.

Ommmmm...

Jon

Its a mixture of all three. There are two main ingredients to squirtycream, cream and nitrous oxide. The cream is made up of at least 30% solid and liquid milk fats, and milk proteins. Nitrous oxide when under pressure is dissolved in the fats, but comes out of solution when the pressure is released - when it is squirted. It acts as the propellant, and also whips the cream. While squirting the cream, the fats and protein surround the nitrous oxide gas, which stiffens the mixture.