Can be 2 part poured. To clarify can also be injection molded, RIM, Reaction Injection Molding. According to the school textbook 20 years old I literally pulled off the shelf…
“Two components, an isocyanate and a polyol are pumped and metered to a mixing head where they are impingement mixed under high pressure. The mixture is then injected into the mold at a low pressure of 35N.CM2 (50psi) and a low temperature of 65+/-20C. The mold is filled to 20-50% with the mixture which foams and fills the cavity. To keep bubbles in the part to a minimum the mold is oriented so that the mixute enters the cavity at the bottom and rises to the top”. To get best results the gate should be placed so that the more intricate areas os the part cavity are filled before the foaming begins. The thickness of the skin formed is dependent on the temperature of the cavity wall…"
From Mass Production Technology for Industrial Design Part 1
M. de Leeuw
School of Industrial Design
That book is STILL my bible and from one of the best courses I’ve ever taken!
I also still have Part 1 and 2 of these Mass Pro books. Both are essential (ying/yang). When you’re outnumbered by Engineers 30:1 it helps to know your basic MFG & materials. Makes you more grounded than just a fluffy aesthetic guy.
A vendor I deal a lot with is UFP Technologies based in Georgetown MA. They do IMEVA too (aka CROCS).