Thanks to help from Bulldog I have improved on my tile work.
Getting better but still some work to do. There seems to be some unevenness in the output, you can see like a binocular effect in the bottom centre of a darker patch. Not sure what that is… It may be the original image.
There are also lines going down the image which is strange as I engraved across the image???
800mm/min
100 power
Jarvis
3.5w diode
2hr 9mins
Brilliant picture, lines probably down to belt tension 
Thanks for sharing the photo and the settings, without this information it is “just a fine” picture.
What is the ‘belt tension’… I am using a 3018cnc machine so not sure if this would apply???
No,i guess it wouldn’t 
Looking good…If tile not cleaned first and uneven coat…or not dry tou will get blotches
The vertical lines indicate a mechanical issue with your laser gantry (x axis)…loose belt…debris in gear…belts…loose wheels…wobbly lens…loose laser module…You especially see these lines in tiles…(with wood the burn radius generally hides this anomaly)
tile will show any little anomalies with your system…I,ve spent hundreds of hours trying to solve this …
Basic Mechanical Checks:
Remove all belts from steppers
By hand move both gantries up…down…side to side applying both horizontal and vertical pressure
Feel for any bumps …tightness…wheel slop…bearing wear…stepper bracket moment…
Clean all the track v-grooves and wheels
Grab the laser module …see if there is any movement play
Same for Laser lens
Ensure that x and y gantries are at 90 degrees
Put belts on and ensure tightened correctly
Okey dokey… All noted.
I ha e now tightened all screws etc, a few defo needed a good turn. Hopefully that will solve the lines.
I thought even coverage of the paint might affect the patches… I find getting an even coat tricky to be honest (I’m not the great at spray paints).
I have however managed to ‘colourise’ the tile though. I’m really chuffed with this now.
