I suspect, btw, that in modern art practice most of the old varnishes have been superceded by acrylics... I need to cover some prints where I don't want to use glass. I plan to try liquitex high gloss. Has someone done that? With inkjet? With gum?
With gum no problem to start directly with some varnish (i tried different ones , spraying and brushing) but with inkjet is a different story: in both cases -dye&pigment ink- i first start with spraying several thin layers of something called FIXATIF (an acrylic based stuff also used for pencil, charcoal etc. drawings), after that it is no problem with varnishes, spraying, brushing etc.
Succes and bon courage .... forget about the 'under-water-shining', i think it is comparable with something like a perpeteum mobile ....