Not sure if this is help to anyone but I use this as a rule of thumb some friendly advise
Static Grass 2mm has been around some time for some time, however 4mm 6mm and certainly 10mm 12mm is a pretty new concept to the modelling world.
So some hints as to where to start
If your Modelling in double O gauge we suggest that you use your 2mm grass as a base grass. it covers well there is no need to paint your base board first and the bold colours are a good start.
Then your 4mm and 6mm grass is your detailing grass
This is where you can add the great colours and height to the grass, make sure you lay in patches. Some 4mm in an area and the 6mm in another, the idea is to multi layer. You can add Patchy Grass and Dead Grass to give you loads of different tones.
Last is the 10 mm and 12mm
These are used a s a finishing grass.
If you have embankments, unkept areas, around loco sheds, behind stations, in a field of battle on your diorama. These will give you the tall grass or as a haze over your wild meadow.
Tools it all starts with a good applicator. It should have the heads to allow the different sized heads to fall through.
A good basing glue, one that will carry a good current from the applicator.
Layering Spray for your detailing and finishing grass
With these techniques there is no reason why you can not achieve a finished area of 1m squared with in 10 minute. You do not need to wait for the glue to dry and with a good selection of colours from WWS you can achieve a real