It means you have a major leak in that hose. Orange residue is leakage of caltex coolant, water evaporates but coolant does not and that's what you're seeing. Is it at joint or in the hose? How much loss do you see in radiator after 20-30 min drive? Did you test the t-valve before putting it in? To check now, start car with radiator cap removed after sometime when temperature is reached you should see coolant flow from radiator neck. While you're at it check temperature of radiator from top to bottom, there should be gradual temp change as soon as t valve opens. I still think your radiator is blocked if lower hose is not hot to touch or your t valve is faulty. You can't tell the difference by hand between upper and lower hose temp on a warmed up car.
BTW don't even consider gasket job until your cooling system is upto spec. Mechanics misguide in this regard.
