I've never tried gelatin sizing for an inkjet print.
Normally, I buy good coated papers, like Arches Infinity (basically, classic arches hot press and cold press with a factory applied coating).
Sometimes I run regular ink jet papers under control of a RIP that lets me run outrageously high ink limits, say 400% (amazing what you can do with the right software) and get pretty good results, very reminiscent of an actual watercolor.
If I were to try to coat my own, I'd be more likely to try an ink receptive coating like "ink aid" than plain gelatin.
And even more lik