I have tried just about everyone method with either bad or inconsistent
results. so as per usual I did my own thing. I use Ti02 powder, water and tempura paint. I use a cheap detail HVLP from harbor freight and usually do a couple coats.
draw back slow drying and needs multiple coats, but the back is very black and I have my mixture down and application down and it is very consistent. I do still do a test on each new batch of mix i have to make sure I did it correctly sometime I forget things… like the second coat. I’m not saying other methods are good or bad this is just the method that has worked for me so I’m staying with it for now. Maybe it can help others.