Coating Inkjet Prints -- As of 11/20/02

I have been experimenting with print coatings that raise the dMax to over 2.0 and make the fragile surface of the inkjet prints much tougher and more durable. Frankly, the coated carbon-pigment prints I've been making have a visibly higher dynamic range than my toned silver prints, and the coated surface is so tough that the print can be displayed without glazing. Once the glass is gone, the dynamic range of the print can really shine.

I don't expect conservative gallery owners to accept the idea very quickly, but side-by-side with glazed B&W prints, the unglazed, coated inkjet prints will speak for themselves.

The usual print sprays that we can buy cannot give the dMax increase that I am looking for. A thicker coating is needed.

So far, I favor applying the coating with a #30 wire-wound ("Mayer") rod (from Diversified Enterprises 800-833-4644) for Epson Archival Matte ("EAM") and a #15 for Eclipse Satine. For 8x10" prints I've been using a 16" (12" of winding) 1/2 inch thick rod that sells for $22 (but there is a $25 minimum). It's the only process I've tried that can do a perfect finish in one coat.

For coating material, some on the Digital B&W Print forum like the Golden water-based acrylics for the first coat. The Liquitex version -- readily available -- at 3 parts Liquitex to 1 part water is also a good coating. In fact, I favor something like the Liquitex because it has no UV inhibitors, which often yellow the print too much.

I currently think polyurethane ("PUR") may be a better coating. It's superior toughness and resistance to humidity and chemicals may have significant advantages over the acrylics. The best practical answer I've found is the water-based (easy, even if not at tough as the 2-solution, solvent-based, industrial-strength ones), aliphatic (non-yellowing), Hydrocote (800-229-4937) Polyshield Gloss PUR. This is available in one-quart size via mail/telephone order. The wire-wound rods apply it easily with no dilution. It dries very quickly, but takes about 7 days to cure completely.

The two papers that I've used that work the best are Eclipse Satine and EAM. They both can be coated with a single application. The finish ends up a pearl/luster that is very nice, although this is clearly subjective. For a flatter finish, Legion Photo Matte may be a good choice. It also coats well with one coat using the #15 rod.

To apply the coating with a rod, I tape the "top" 1/8 inch of the print to a piece of 1/4" thick glass using Scotch Removable tape. (Have the print upside down so that the larger bottom border is the one taped.) The glass is for a smooth, flat surface that I can razor off dried coating if necessary. I've been using a couple sheets of copy paper under the print. For some papers it helps also to tape down the bottom corners, although I usually don't bother with this.

About 7 cc (for an 8x10) of Polyshield pulled straight from the can with a syringe fitted with an MIS bottom-fill attachment is used to lay a "bead" on the tape and glass above the print. I make sure there are no bubbles in the PUR not only before I lay down the bead but also after the bead is on the tape & glass. I pull some water into the syringe and discharge it immediately a couple of times to stop the PUR from setting-up in the nozzle.

Just before pulling the rod across the print, I use a blower to be sure there is no dust on it. Since the can of PUR is only open long enough to pull out what I need, there should not be any significant amount of dust in the coating material (I hope -- so far, so good).

After the "bead" (or small, long pool) of coating is on the tape and glass above the print, I pull the rod through the bead and down across the print. The weight of the rod supplies most of the downward force needed. I don't roll the rod, but rather drag it smoothly and not too slowly, keeping the speed of the pull as constant as possible. If I get horizontal banding, it is often because I've pulled the rod too slowly. After I've pulled the excess coating away from the bottom of the print, I immediately rinse off the rod. I definitely don't want the PUR to set-up on the rod.

I quickly remove the tape from the print. If the PUR sets-up too much before the tape is pulled off, it will pull off part of the print paper with it.

I usually put the 8x10 print on a dry paper towel as soon as possible. The screw-driver that I used to open the can makes a handy tool to run under the print edges to separate them from the paper and glass under the print.

A damp sponge soaks up the excess coating material and will clean the glass easily.

Once the glass is clean and dry, I usually pull the print on its paper towel back onto the glass and dry it a bit with a hair drier. By this time it is also dry enough to just hang up to dry.

Between the tape, handling and other problems, I lose a little less than 1/4 inch of each print edge, but that still leaves a good 8x10 print area.

I'm still experimenting with this, so my materials and methods may change.

While the coating process is still experimental, I think it holds great potential for taking our pigmented inkjet prints to a level that, in many respects, exceeds the quality of the traditional silver print.


If you have any comments or questions, please do not hesitate to contact me.


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Paul Roark
Solvang, CA
USA