** These suggestions/experiences come from using a 256 electrode EEG hat on human subjects. **

====== Setups that make your life easier ======

Have multiple people squirting gel in the holes. That way the subject gets less bored. 

Tell the subject to go to the bathroom before they sit down with all the electrodes on. 

Put gel in all the holes first. Then put in the electrodes. This will save you time (all those little inefficiencies form lifting the syringe etc)

Keep the monitor on which you can watch the channel data in the same room as the subject, so you don't have to run back and forth in order to see if a channel is good or not. This will also entertain the subject. 

====== 60 hertz!!! ======

Electrical noise can plague your channels. Remove all unnecessary electrical equipment from the room. Pray. 

====== When a channel is bad ======

1. Pull out the electrode, put more gel in the hole and put the electrode back in. Do this a couple of times. Wait while looking at the screen. The channel won't become normal right away, but it might after a few seconds. 

2. Pull out the electrode and scrape the person's scalp with the tip of your syringe. Be gentle. You can try this a couple of times too. 

3. Forget about it. Some channels break over time. Label them as bad somehow (you could keep a log of bad channels in your lab etc.) and leave them out

====== When all the channels are bad ======

Check the reference electrodes, it's probably their fault. Treat them like a bad channel. This situation can be very frustrating because when the reference electrodes are bad the whole display screen goes crazy. 

Otherwise, you can try unplugging and plugging back in the wire clusters. They might have a bad connection. 


====== How to entertain your subjects ======

Show them movies, TV shows or give them comic books. You don't want your subject to be more irritated/bored than necessary when starting the experiment.

====== Cleaning an EEG hat ======

Cleaning an EEG hat with 256 electrode holes full of gel can take a long time. These are several techniques you could use:

** Squirting water through the holes one by one  **

This works but it splashes a lot of water around. It also uses up a a lot of water unless you have a pump and a bucket (instead of a hose and sink.) The water pressure has to be very high for all the gel to go out of the holes. 

** Sucking the gel out with a syringe **

If you have a gelled hat, you probably also have the syringe with which you put the gel in the holes. You can suck a lot of the gel out of the holes with a syringe (push the piston up quickly). This is faster but doesn't remove all the gel. after you wash the hat at the end, the remaining gel forms a film over the holes, so next time you use the hat there are hardened films to poke through

** Washing the hat in a bucket/leaving it there **

This doesn't really help, although the gel is supposed to be water solluble 

** Blowing the gel out with your mouth **

This works well but it's unsanitary and who knows what's in that gel? :)

** Blowing the gel out with an air pyston **

This works much better than the hose variety , because you skip the messy water. What you really need is something with a lot of pressure and a mouthpiece which fits snugly inside each hole. 

** Other? **

There must be better ways of doing this. Someone tried to put the hat over a plastic ball and squirt all the holes out at once. There is a pressure problem here, because that gel is holding on to the hole edges really snugly.