Artemis BJJ (MYGYM Bristol), Can Sönmez, Bristol, UK - 24/06/2015
To begin the americana, grab their wrist with your opposite hand. Grasp their elbow with your other hand. Keeping both of your arms straight, lean diagonally forwards, using your weight to drive their arm to the ground (as per the picture, you can also follow Cindy Omatsu's example and use your head to add further leverage). The elbow of your wrist-gripping arm goes next to their head. Remove the grip you have on their elbow, then with your palm facing up, slip that hand underneath their elbow. As it slips under, turn your hand so the palm faces down.
With the hand you just slipped under, grab your other wrist. This means you now have a 'figure-four' on their arm, a solid grip. To complete the submission, keep your head down and lift their elbow, pushing their knuckles back in a straight line along the ground, like a paintbrush. You want to move their knuckles, rather than pulling their elbow down as well: that goes up (but only slightly), their knuckles go back. Also, keep the knuckles in contact with the mat.
You can also vary your angle, which will affect how far you have to push their knuckles. For example, Saulo Ribeiro teaches sucking the trapped arm in to their body, then lifting the elbow. His angle is such that he doesn't need to paint the hand back at all. It will also vary depending on the flexibility of your training partner's shoulder. Finally, you can try twisting your fists downwards, like you were revving a motorbike. That should further increase your leverage.
Finally, Rener has a helpful tip on securing your base when going for the americana. He likes to slip his opposite side leg underneath theirs, twisting his hips slightly in that direction. That's worth giving a try if you find it difficult to stabilise the position when you're trying to finish the submission.
Teaching Notes: I always mention using the head to push down the arm, but nobody ever does it. Not that it's essential, but that indicates I should probably be demonstrating it rather than just mentioning you can use your forehead. I also didn't mention looping the arm around if you ended up holding under the head, but that didn't come up in sparring or resistance anyway. Worth putting in though. As the class wasn't too big, I had time to run through an armbar from guard too.