Advice needed

[beginner-James]

Evening folks or Morning depending where you are in the world.
I've just been painting with Golden transparent paint and I need advice.
I'm spraying a fine blending in light green very light green
28 drops titanium White
14 water glycine mix
1 green
1 shading grey (as this has blue in it I thought I would or could use it) and it worked out quite well very close to Pantone 558u

but the problem is I can't see it hit the board. The only way I can see the paint pattern is by painting the blue masking tape first I was using a white shield as well.

Maybe I should spray a black shield first as I don't have any black card or paper

Beginner-James

 

[beginner-James]

and if I light it up with easel light ok DIY desk light I can't even see the colour. But I'm sure in the morning sunlight I will see it as to dark a blending if that's the case how will I go about lighting it up.

Beginner-James

 

[erwin de pan]

It is difficult if you can not see what you are doing.
If you put a white paper next to it, can you see the difference?
It is a covering color that you have made, so to make it lighter you can use the same mix with a little more white.