Hi.
I'm Catmacey (Matt Casey) the author of the site mentioned in bebx2000's post.
The chemicals I used to etch boards are the standard off-the-shelf choice here in Barcelona (Spain), the manufacturer Repro Ciruit are based here too. Their catalogue is here
http://www.reprocircuit.com/00-archivos/catalogo/fraccionado1_15.pdf but has no additional info...
Most of the eletronics stores here in the city carry the same brand alongside ferricchloride.
I'm not certain of the exact composition stengths or the chemical process involved. I just know that it works. You get a litre bottle of the acid and a smaller tub of the perborate. The idea is to mix them in equal relative proportions eg. half the bottle of acid to half the tub of perborato. It's pretty tolorant of inaccurate proportions and will keep for a week or so in an airtight tub once mixed. I tend to make it up in small quantiies, just enough to do the occasional board or two. Then top it up with a bit more acid if it's not working fast enough.
Hope that's helpful
Matt Casey