There are several types of secondary flaking or retouch, the two most important of which are backing or blunting retouch, and invasive or normal retouch. Invasive retouch can be steep or shallow, depending mainly on the kind of edge being retouch; this retouch can also be scaly in character. Backing is most often applied to blades to blunt the back or to bring its end to a stout point. I'm not familiar with French, but since écaille means (I think) .scale, I would presume invasive retouch is what you need here, IMHO. (PS: I'm having a tough time responding to KudoZ....)

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Note added at 11 hrs (2006-10-04 17:51:55 GMT)
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On the other hand, it may be scalar (in steps): see for various (illustrated and defined) retouch types at:
RETOUCH TYPES
Scalar retouch, or scaliform retouch type, is a semi-abrupt form which fractures on the end of the removals in steps or scales. It is a more extreme form of ...
www.hf.uio.no/iakh/forskning/sarc/iakh/lithic/retouchtype.h...