First of all, I think it is 'encre' = ink!

I suspect this is talking about a process that used (back in the 60s, at least) to be known as 'thermography', which was a poor man's alternative to true embossing.

We used to print with an ink which was then passed under a heater, and it would swell up and produce a raised, shiny letter.

From documents I've seen, a process ostensibly similar to this still seems to be used sometimes for posh companies' letterheads, etc.


Perhaps this link might give some clues:

http://cat.inist.fr/?aModele=afficheN&cpsidt=13900906

Although the FR term does indeed seem to be "thermographie", it is clearly used a lot more widely than just in the printing field.

Here you go, this is getting closer:

Fondation québécoise du cancer: Première source d'information au ...

L'impression thermographique utilise le chauffage d'encres spécialement traitées afin d'imprimer des lettres en trois dimensions, simulant ainsi ...

www.fqc.qc.ca/encyclotexte.asp?id=143


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Note added at 15 mins (2007-03-28 17:02:39 GMT)
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or simply 'thermography', of course, though I think that is more ambiguous, given other current uses of the term.