How to back paint clear plexiglass so I can reverse laser engrave?
I'm trying to back paint a piece of clear plexiglass so that I can reverse laser engrave. I'm then going to backlight the piece with an LED panel but I want the paint to be opaque so that the light only comes through the engraved pieces if held up to the back painted side. It will then have a nice look because the clear acrylic will give the lasered piece floating characteristics. I'm able to create this effect using black krylon fusion spray paint, but it just seems to take 3-4 coats in order to block the light out through the paint. I've tried black vinyl, block out sign vinyl and a variety of painted applications but nothing seems to work better than paint. The vinyl applications are also troublesome because the margin for error is too high with vinyl applications as I need the piece to be very consistent on the black reverse side.
I've also found products out there specially made for reverse engraving, but they are extremely expensive, and upwards of 150$ for 24" - 48". I've talked to a couple people that recommended Krylon Fusion normal paint, I'm just worried that if I were to use a roller, or brush, I'd see the brush strokes from the clear side and it would ruin the piece versus using spray paint, which is slightly difficult to get a consistent piece.
Does anyone have any recommendations for what kind of coating or solution I would be able to use?