I only referenced GFS in my above post, but (the more delicate) FB AL was even worse. Smaller GFS or FB AL (awesome paper for B&W) no worries.
I think the larger-width sheets simply have more latitude to distort when under ink. From what I've seen it does seem to vary by printer copy + and printing circumstance. Like any mechanical device working with tight tolerances, it doesn't take much copy-to-copy variation to allow a paper that won't remain flat under ink to contact something it shouldn't with some units. There are also no shortage of bits in the paper path at the ink and post-ink stages of the 3800 that will happily scratch the surface of a delicate, wet, ink-laden paper.
The grain runs in the opposite direction with FB Al large sheets than it does on the smaller sizes. It may be the same with GFS. I'm the guy who wrote the posts on spraying the backs of the 17x25 sheets of FB Al. I have an Epson 3800, and I'll agree that part of the problem is with the printer construction. It's a great printer, that I call my GPH ("Great Printer from Hell"). The new 3880 that a friend of mine has is somewhat better, not prone to scratching in the long direction, but still prone to head strikes at the corners if the paper isn't flattened first before going into the printer.
I've found that the best way to store any paper is so that it is horizontal with the backs of the sheets up. That way, when you pull out the "top" (formerly bottom) sheet in the stack, it won't scratch the sheet below, even if the corner drags as you pull it out, because it's dragging against the back of the next sheet (before adopting this storage procedure, that was another problem). The upside-down sheets seem to lay a little flatter, too.
With my printing procedure, I place the sheet face-down on a clean, smooth surface, bend the sheet edges, one edge at a time, gently toward the opposite edge and then manually "de-curl" the edges, regardless of the size, brand, or type. I do the bending by hand, being careful not to bend it so much that the surface will kink or crackle (which the Harman will do at the drop of a hat). Once it will lay dead flat upside-down on my Foam-core drying board, I gently spray the back of the paper with a little sprayer that you can hold in one hand. I smooth the water out by gently dragging a folded piece of paper towel across the sheet from end to end and side to side, until there is an even, streak-free distribution without gaps, making a very thin film of water. I'm careful not to let the sheet shift around while I do this, so as to avoid wetting the front surface.
Then, I go do something else, such as setting up the print in my favorite printing program (not Lightroom or Photoshop). The sheet will curl downwards on the edges and will lift in the curled areas almost an inch off the board. Once it has settled back down such that the edges have no more than about a quarter of an inch of curl along the long edges, I gently pick it up by a short edge and load it into the 3800. Using the sheet feeder, and making sure that the paper is sitting straight as possible against the back of the feeder at the leading edge I then hit the rectangular "advance" button on the printer. The paper advances to the starting position and stops. At this point, I go finish my settings for the print, taking my time to let the paper dry a little more. For the Harman FB Al, I use thickness and platen gap settings of 5 and Wide. Then, I hit "Print."
The slight amount of moisture in the back counters the tendency for the ink to curl the paper the opposite way from the front (the "seagull wing" shape described in an above post). After adopting this procedure, the persistant problem I had been having with scratches in the long direction on 17"x25" Harman FB Al completely stopped. No more scratches, and no head strikes.
With the Harman paper, it still is somewhat delicate until the pigment has been allowed to dry for a couple of weeks or more face up in the drying rack. The pigment ink particles are encapsulated in a sort of resin that, itself, is prone to scratching until it really hardens. Once it does so, it partly protects the paper from it's own tendency to scratch.
With your climate, which may be more or less humid than mine, you may have to make adjustments. I believe that the paper may have been made in a climate that is cooler than where I live. Though the manufacturer brags of a construction that resists curling, I've found that a sudden increase in humidity, as during a rainstorm, will curl the Harman papers of any size a lot. A small strip of the paper can be used to test that in your area. In one instance, a 6" long by 1" wide piece that I used to test the curl, bent on its own into a complete circle (with the front surface of the paper inside the circle) during a brief rainstorm here that briefly raised the humidity, and gradually flattened back out on its own after the rain stopped.
The Harman Gloss Al isn't perfect, but it's still my favorite glossy paper to date for it's smooth response, detail, and surface that's just slightly glossier than a good air dried glossy silver print. If I could advise Harman, I'd say to get ahold of some good silver print paper, like Oriental, Brilliant, or the like, and emulate the texture of that (Epson Exhibition takes the surface texture a bit too far for my taste). Then, really don't just "say" that you have beefed up the boxes, make it happen! The Hahnemuhle boxes are much better, far less prone to bending and crushing at the corners. I've had a lot of the large Harman paper arrive with dinged corners from most of the major US vendors. That gets costly. I'd rather pay for better packaging of the paper at the factory than totally rely on the vendor to bullet-proof the shipping box, though I'll insist on that, too. Also, the plastic sheet around the paper looks smooth, but almost always slightly abrades the surface of the top sheet in transit, ruining one sheet per box.
Good Luck, Happy New Year, and Aloha,
Aaron
