Snuff back controlled coating dispensing apparatus and methods

A method of dispensing conformal coatings from coating apparatus and onto substrates, the method comprising the steps of:

• dispensing a first amount of conformal coating through a discharge of a nozzle, said discharge slot having an outlet;
• depositing said first amount of conformal coating on said substrate to form a first coating pattern thereon;
• stopping the dispensing of said conformal coating;
• after said stopping, then activating a snuff back device to withdraw conformal coating into a snuff back passage communicating with the discharge passage and away from said outer;
• thereafter dispensing a second amount of conformal coating through said discharge and from said outlet;
• and
• after activating said coating apparatus to begin dispensing said second amount of conformal coating, reactivating the snuff coating device and discharging at least a part of the conformal coating in said snuff back passage into the discharge passage.

Coating apparatus comprising:

• a pressurized coating supply;
• a dispensing device including a discharge passage having an outlet and a snuff back passage communicating with the discharge passage, said discharge passage being operatively connected to said coating supply by way of a valve connected between said dispensing device and said supply, said valve operative to selectively allow coating material to flow from said supply into said discharge passage;
• a snuff back device operatively connected to said dispensing device and including means for selectively withdrawing an amount of coating material into said snuff back passage and away from said outlet once said valve is closed;
• and,
• control means for actuating said snuff back device to expel at least a part of said amount of coating material from said snuff back passage after said valve has been actuated to allow said coating material to flow into said discharge passage.