Digital BW, The Print

There are several good reasons why you might want to spray an ink 
print, for example:

- hide bronzing,
- protect the surface from fingerprints, etc,
- add some waterproofing,
- protect from harmful UV,
- increase longevity,
- ... and perhaps others too.

Should I take on trust that the chemicals sprayed on (e.g. Lyson 
Print Guard) are actually totally harmless to the print?  Am I being 
naive?  It does hide bronzing - I can see that; it does provide some 
waterproofing - I've check that; but surely the solvents and 
whatever other stuff is in the spray will interact in some harmful 
way over a longer period of time.  Does anyone know of any science 
to support the "harmless"?

The reason for the question is that I like the idea of what the 
spray achieves and am considering it's use on certain papers - 
PermaJet Oyster - to hide bronzing) and on prints for sale on 
Hahnemuhle PhotoRag and PermaJet Alpha and Omega.  But once sprayed -
 it's permanent.  Just how risky is this?

I've seen reference to spray being used on glossy and matte, coated 
and uncoated papers with dye and pigment inks.  Can one spray really 
be ok for all of these combinations?

Any contribution to either put my mind at rest, or frighten me off 
using them would be appreciated.

[I've tried searching this group but I'm sure I've not been able to 
find some of the previous references that I've seen to spraying.] 

Steve
http://www.virtuallygrey.co.uk