curious alternative to impressioning

[GringoLocksmith]

On Saturday in the shop I made my first attempt at impressioning a key. The other guys looked on, incredulous. None of them use this method, and most don't even know about it. Ultimately I validated all their doubts by failing to produce a working key.

But then the one co-worker whose Spanish I never understand decided to show me a different technique. After picking and rotating the lock, he took out a box of matches and tore off the heads of about five of them. One by one, he put them in his mouth, gnawed on them a little bit, and then stuffed them into the keyhole. I guess he expected the plug to turn freely once he got enough matches in there. But he tested it too soon and the upper pins snapped back into place when he spun the plug around. I had to disassemble the lock to dig the soggy matches out of it with tweezers and picks.

My question:

How was this process supposed to work, and what's the term for it in English?

[elbowmacaroni]

I suppose that is similar to the idea of packing with floss... I'd still consider it to be a form of impressioning

[femurat]

Since he did it after picking the lock, I don't think it's impressioning. It's just, as elbowmacaroni said, an alternative to filling the keyway with dental floss to prevent the pins from falling when you turn the plug. I'd call it an alternative to a plug spinner

[rai]

Floss packing was used by Zeke 79 to fill the keyway on a sargent keso I believe, because there are some traps that pins fall into to lock up a cylinder that is turning without a filled keyway, memory is vague on the exact setup but it was once explained in zekes post.

[gnarus8429]

I have done it with heavy duty (carpet) thread and had success. On the other hand I tried it on door trying to recover evidence in a homicide case that I picked the wrong way and failed. I think that the problem was there were just too many people watching and that affected the canooter valve on the lock. I'l have to try the floss the next time. I would think that he wax would be advantageous in helping the string hold its form. Definitely not 100% but, if you don't have a plug spinner its worth a shot.