0. Drop is empty
Check the entire depth of focus in the drop, try dark field illumination to check for gelatinous precipitate.
If the protein in the drop in the initial screen does not precipitate,
In an optimization step, clear drops can be used for seeding with crystals from neighboring drops.
- repeat this condition with a higher protein concentration.
- If limited amount of protein is available, place the clear drops over a reservoir with a higher precipitant concentration.