So far, I've been in the #2 camp, that IGSF and Canson Baryta are very similar, likely made in the same coating plant, but slight differences can be appreciated. However, your question gave me purpose to go through the AaI&A database, compare LAB values, pull a couple of sheets from these two brands that I have here in my lab and flex them, examine under black light, look at their surfaces under raking light for texture difference, and lastly spray them with Premier Print Shield side-by-side to see if they absorb the spray identically.
My results were:
1) L*,a*, b* media whitepoint = statistically identical.
2) UV blacklight examination = identical
3) substrate thickness = identical
4) anticurl layer on verso = identical
5) baryta odor = identical
6) texture under raking light = identical within subjective visual rating limits
7) substrate rigidity/flex properties = identical within subjective rating limits
8 Scuff resistance on unprinted surface = identical
9) Spray absorptivity - not quite the same, IGFS absorbing more spray and staying "microporous" rather than "sealed coating" until somewhat higher amounts of spray applied
Item 9 is subtle, admittedly subjective, and may be a batch variability issue, but the reason I didn't take to IGFS when it was first introduced was its scuff resistance combined with difficulty in coating with the ultra low viscosity sprays like Premier Print Shield compared to other "traditional fiber papers" like HN photo rag Baryta. The Canon Baryta I purchased seems to be a little easier to coat successfully in just one or two passes, IMHO. The IGFS seems to take three successive coats minimum to cover uniformly.
So, my conclusion:
Well, for all practical purposes end-users will conclude these are identical papers so buy on price, and it's almost guaranteed they are coated in the same plant with essentially same image receptor coatings and anti-curl layers. However, Canson could be supplying the base sheet for it's branded version of this product, whereas Ilford may be getting a base sheet (roll) for IGFS from another paper mill. Physical properties can be spec'd very very close and underneath the coatings would be hard to ascertain that they are different, but Canson could legitimately be providing a chemically different alphacellulose base paper for coating (there's a lot of other chemistry and physics in paper making besides the fibers). We have no easy way of knowing, but if I'm correct, then it would be consistent with other's findings that the papers curl slightly differently when wet with ink. Moreover, Canson could be requesting Ilford to make other slight modifications to the coating chemistry that we don't know about. That plus subtle base sheet differences could account for why I'm seeing differences in trying to top coat them with Print Shield as well as why others like MR seem to observe subtle differences in the two products.
cheers,
Mark
http://www.aardenburg-imaging.com
