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Plastic type materials do tend to not steal as much heat as glass does.
For what it's worth, glass has a very poor thermal conductivity. The problem is that it's at much cooler temperature than the extrudate if it's not heated.
I've never had much luck without a heated build plate. I tried a lot of combinations and nothing is as rock solid as Garnier Fructis Extreme Hold on a heated (50º)bare glass bed. In fact, I print ABS on that combination now at 110ºC and it generally holds better than Kapton with ABS juice! The vinyl hairspray becomes whatwhat gooey when heated.