Well, actually, Polaroid silver prints are subject to dichroic fog or bronzing if the pH is not right and if they are exposed to oxygen, and this is why they apparently need a stabilizing agent. That is what the print coater is for. I suppose that lacquer may be ok, but IDK. Never tried it. Our coaters used to dry out and I asked about the contents of the coater so I could make my own. I was treated to a lengthy description of the reasons for it and the contents but this is about 40 years ago so I have no memory of it except what I said above. It is apparently a lot more complex than the MSDS would lead one to believe.

I don't think Polaroid would go to all of that trouble if it was not useful in some way.