OK, actually trying the spray bottle now. MUCH MUCH better!
Lots of thoughts:
Although I saw online that TiO2 is supposed to be very soluble in ethanol, it’s not. Basically zero. I got some results by shaking before pumping, dried real fast, nice
The water/TiO2 mix can do a pretty wide range. But, whatever I do, I kept getting the following:
Each pump must be a hard, fast squeeze to avoid spattering. Good idea to point the first squeeze away to avoid spatter.
But any way you do this, it is never going to make a fine mist. It will land and dry as droplets.
Attempting to make one continuous sheet layer like you would with paint tended to just streak and crack up as it dries.
But, here’s the key- never go that far. Mist it down, not enough for droplets to merge. It will be blotchy when it dries. Light mist again. If you do too much at once, it will dissolve and move the prior layers.
As has been said, look at it at like 45 deg with a light source on the opposite side. If you see ANY spot of glossy tile, that will not burn black. As long as you see matte surface, you don’t need more.
This suddenly burns WAY faster. Very black at 50mm/s. Was 10mm/s with spray paint.
Washes off easily. Surprised I wasn’t clogging the spray bottle.
Wasn’t using PVA glue. Started to work on another idea that I think is better.
PVA white glue is “polyvinyl acetate”.
There is also PVA “polyvinyl alcohol”, PVAl, used as mold release for castings. It covers even very slick surfaces well, dries fast, water takes it right off- much easier than PVAc. Or it just peels off. They used to sell one with purple color at Hobby Lobby, I have an old one.
Polyvinyl alcohol might be pretty useful, I didn’t get a chance to try it fully. It could have a key advantage over PVAc glue in that it washes off much easier. But just water and TiO2 is working pretty excellent, the only prob I’d want to try to “solve” is being able to lay down a whole wet sheet layer instead of misting over and over.
The layers can be very consistent and burn a million times better and clean easily with just TiO2 and water. The only complaint is having to do like 5 coats.
I got this to go way faster by microwaving the tile. The mist droplets land and evaporate in like a minute and you can hit it again.
Perfectly dry tile does not get very hot in the microwave. Wet the back first, let it soak, unglazed ceramic is porous. It’ll get super hot and that’s best, each coat flash-dries. You can also dry a coat in the microwave.
At 50 mm/s, the LI went back down to 0.1mm. It’s pretty great! However, the shading has some issues, I think now it needs that Dot Width Correction which it did not need before.