Physics of why to use metallic (surface) reflectors for UV

Reflective in visible light doesn't infer reflective in UVA and UVB bands.

Unless the reflector has a polished metal or "vapor deposited" aluminium surface , I'd be reluctant to use it as there is a very good chance the surface of the "painted" / powder coated surface will actually absorb UVA & UVB and perhaps reemit the light in the visible bands thereby defeating the purpose of using a reflector / reflector hood partly or even entirely ( all the UVA & UVB may actually be absorbed and fluoresced as visible light ) , see below for basics :


In short - if the reflector is not designed to reflect better than 80% of the UVA & UVB that falls on it's front surface , it's not suitable for use in a reptile enclosure. This means the reflective surfaces are restricted to copper, aluminium, gold or silver.

See this for specular reflectivities of some reflective surfaces :

Ref : Evaluation of reflectivity of metal parts
InfraMation 2010 Conference Proceedings p210-p243, Z. Sarosi

Reminder :
UVA, or near UV (wavelengths 315–400 nm)
UVB, or middle UV (wavelengths 280–315 nm)

This is why I'd be looking for a polished aluminium reflector or a vacuum aluminized surface on the reflector.
The substrate behind the reflective surface is irrelevant ( it only forms the focusing shape and holds the reflective surface in place ).

Interesting note :

There is an paint that is highly reflective in the range 300 - 400 nm designed to hide aircraft and vehicles and artillery in snow country .
It's general composition is :
essentially of 40 parts by weight of calcium carbonate,
l0 parts by weight of highly viscous chlorinated rubber,
6 parts by weight of chlorinated diphenyl,
and 44 parts by weight of xylene.

Ref United States Patent O 3 300,325
CAMOUFLAGE PAINT REFLECTING ULTRAVIOLET LIGHT FOR USE IN SNOWY COUNTRY Filed April 1, 1965

That's so interesting research, I've never even think about such details

@focussport I agree with you, these details are even ununderstandable for most people. Remember my school time, I hated math and physics as others and used some sites such as
https://plainmath.net/35983/two-firms-v-and-w-consider-bidding-on-a-road-building-job-which-may-o to do my study tasks without my involvement. But then I understood how important to know such things at least on a base level.