Glaze or other clear protective coating over veneer plaster?

[historian]

I have veneer plaster over blue plasterboard (interior walls) and foamed e-crete (exterior walls). I built the house but did not apply the plaster. We've lived here ten years and the plaster has held up well except a few cracks and pop-outs. The finish is not smooth but more like stucco. I want to apply some kind of glaze or protective top coat: clear or lightly toned, glossy or matte, but easy to apply without noxious fumes and able to take the occasional spot scrubbing. Product suggestions? Thanks.

 

[casplas]

Varnish .... water based or oil based , or pva and water 4-1 mix 2 coats, just not sure pva will take a scrubbing , Thompsons water seal, all will work depends how hard your scrubbing

 

[Loren]

I imagine you do not have paint on the walls and you might have a pigment mixed in with the plaster? Well around here we have been using a good coat of carnauba wax, and if you want it glossy you can buff it .