Possible Clues:

• Cause of road rage when followed by a vehicle
• Egg-yolk and water painting medium
• Anger a painter to a medium extent
• Moderate a medium
• Paint one working irregularly with English artist
• Casual worker has time to make emulsion
• Emulsion paint matched up for each area
• Irritation shown with a painter's technique
• That's enough to harden a medium for the artist
• Work for a while, then a long time, painting