In theory, laminating should help reduce fading, because it limits or
eliminates gas exposure to the surface of the print. But that's where
theory ends and conjecture begins.
Laminates come in dozens of formulations, the adhesives, which can make
up more of the laminate than the plastic on many, can be made from
dozens of different thermal glues, or cold adhesives. The plastic
coating can be made of one of a good dozen different plastics, in
different thicknesses. Some may be "breathable", others not. Hot
laminates usually are identified by two numbers, one represents the
thickness of the plastic the other the thickness of the adhesive.
The thermal glues can and do have different melting points.
So, do laminates protect inkjet prints from fading? Who really knows.
I don't know of any tests, and even if there were, which types, which
adhesives, which temperatures. and for how long? Will the adhesives or
plastics yellow or become brittle over time?
The only thing I can say is that if your printer can print well on
non-inkjet paper or inexpensive inkjet paper, you may find it cheaper to
use a laminate. They will be waterproof, glossy (unless you use a matte
laminate, which is usually more costly) and scuff-proof. They will be
thicker as well.
Most people do not seem to like the look of glossy lamination for real
photos. They look too "plastic". Laminating adds cost. Thicker
pouches are pretty costly, roll and thinner laminate can be fairly
inexpensive inexpensive, but don't add much "bulk" to the paper.
Considering the variables, it's very hard to place a "value" on
lamination, in terms of permanence. If you ever hear of any long term
tests, I'd like to know about them.
Art