I finally got some get-to-the-point pics with a new utility truck taillight assembly. Takes an 1157 in the brake/tail light, and 1156 in the turn signal. The reflector bowls were factory-painted matte chrome silver, very similar to the reflector material in our cars.
Here's the taillight assembly as made, with the silvery reflectors:
And after I painted the reflectors white:
Here are the reflectors after I applied Behr
Ultra Pure White, which has a reflectivity value of 94, even higher than the Sherwin-Williams stuff. I used a foam brush to apply it. It goes on thick, and took 2 coats for full visual coverage:
I used a luxmeter app on my phone to record the tail, brake, and turn signal output with the stock reflectors, then with the white reflectors. Same bulbs on the same power supply at the same distance.
Tail, stock reflector and then white reflector:
Brake, stock reflector and then white reflector:
Turn signal, stock reflector and then white reflector:
This isn't a calibrated luxmeter setup, so while the readings are valid (~ish) for more/less comparison, they aren't valid on their own to determine exactly how much light the lamps were putting out.
For fun, I put the best-so-far of the "LED bulbs" suitable for this kind of lamp, in the turn signal with the white reflector:
Yeah, lookit that: less light than the stock bulb in the stock reflector. Pffft.
