These don’t like to warm up

I am pretty sure that these tubes are designed to be used exclusively in closed hermetic fixtures such as weatherpacks or enclosed street lights, enclosed recessed armstrong type ceiling fixtures etc. because these tubes need higher ambient temperature to warm up fully even with reduced wattage so they would start out dim and would heat the interior of the fixture and that would make the tube warm up to its full output. I had left this tube operating in bare air on my QT ballast and it never warmed up but when I installed it under a cover in my hermetic weatherpack it warmed up after 10 minutes to full brightness I wish they would have specified that on the sleeve