Photographing Church Art

As a side project I'd like to photograph some of the art inside the church I attend. Specifically, there are a number of mosaics, about 11"x14" in size and are recessed about 6"-8". They are currently lit with an incandescent light located in the recessed area and I'm fairly certain these lights can be shut off if necessary. Since they are set back, without the light the mosiacs are dark, even if the church is lit well.

I was thinking about using strobe/flash units with a diffuser (one on each side) but I'm not sure how much they would reflect. Also thought using a few continuous LEDs set up the same way. It could be that I may have to experiement but I thought I would ask first. Any tips or advice is appreciated. Thanks.

Think of the subject surface as a mirror...if your light source is positioned to the side so you do not see it in the mirror, the surface of what you are photographing will not be reflecting the light into your lens as surface glare.

If you overpower the existing incandescent light with your supplemental light source(s) by 3EV or more, it will not matter that they are warmer than your supplmental light. Here is a series shot with a 'contaminated' ambient source vs. a 'correct' artificial source, with different levels of mix to show where any contamination is no longer detectable