The effect looks great, almost Van Gogh-ish.

Very repeatitive after a while, but looks really cool.

I have seen the same technique elsewhere, but I don't know how in God's name this effect is achieved.

You just use a blunt edge on the face of a (SX70) polarioid & move the emulsion around. Put polaroid on a hard flat surface & use your knuckle or any intrument that doesn't have sharp edges so you don't damage the outer plastic skin. Works best if done soon after exposure whilst the emulsion layers of the polaroid are still relatively liquid.

Here's this guy that does it too. I created this page for him but his domain isn't up yet.

http://www.twinarrow.com/jeff/

What he does is take those Polaroid pictures and just hold it in his hand and use a key and do his magic. The guy himself is a little eccentric but his work is pretty cool. I didn't know that other people did this too.