The water in your photo paper

[Paul Verizzo]

Yes, there is. And it might be a lot more than you would imagine. Think up to almost a 1/4 teaspoon per sheet.

We all know that humidity is hard on dye inks. Canon even makes a point of how their inks and papers keep images sharp by not letting the ink migrate. To say nothing of H2O being the universal enabler of chemical reactions.

The background: I live in Florida on the water. I have a digital thermometer/hygrostat and I'll estimate that the average, year round humidity is in the area of 70-75%. No AC in the summer which lowers the RH, all natural climate. The paper tested has been here for six years.

To find out just how much water can be in photo paper, I took 20 sheets of heavy 320gram? matte double sided paper, Royal Brites brand. I weighed them on my lab scale, 227.11 grams. I warmed up the oven at its lowest setting with a cookie tray to diffuse the heat. After it peaked and got down to 175F, I spread out the paper over some small bowls to maximize surface area. I kept them in there for an hour, periodically turning the oven on for 45 seconds. The temperature hovered between 150 to 190 degrees.

At the end of the hour, they weighted 214.97 grams. That's .61 grams per sheet! Or, to further check, that's 13 drops of water or almost a 1/4 teaspoon!

So if you have the habit of spraying your dye prints with any typical varnish, lacquer, or shellac, you are locking that water right in!

Some further thoughts:

1) So your paper has a polyethylene coating, front and/or back? First, the printable surface is outside of the PE, despite the forty year old urban legend otherwise. And PE is NOT a moisture barrier. Do this simple experiment: Take a rag or paper towel, thoroughly wet it. Put it in a PE kitchen bag, seal it with tape. In some weeks or months, the rag or towel will be bone dry. I learned this through attempts at cigar and print head storage. Doesn't work.

Therefore, if you spray your prints, do it front and back. After drying, of course.

2) Consider making a simple dessication chamber. I started down this road quite awhile ago, but now I know I will use it! I got a pound or so of silica gel at a hobby store for about $10 and a terrarium hygrometer for about $3 on eBay. A cheap plastic kitchen drawer silverware divider and a giant Ziplock bag completes it. Put the silica gel in the divider, put it into the big Ziplock, lay a paper towel over it to keep the gel off of your paper, put your paper in, and lay the hygrometer on top. Yes, in theory per #1 above that ziplock is not a perfect moisture barrier, but with all that gel and the hygrometer, it would take years to make a difference.

3) I would suggest keeping your paper in the chamber, printing, and then when dry to the touch, put it back in in order to remove any moisture from the inks still within. At zero percent RH, which is attainable, I'm guessing that a day should be sufficient.

4) Even if you live in a desert environment, typical year round average RH is still in the 20%-30% range, all depending on specifics.

5) Consider printing, let dry to the touch, and then spray the back, let dry and then put in the desiccator. That way when you go to spray the front, there is no time for humidity to get back into the paper. BTW, lacquer dries almost instantly, shellac not far behind, petroleum based varnishes the longest. I would go for several coats of shellac or lacquer.

My next archival post printing project could be called, "Beyond laminating and sprays." Why they bring their own problems and what you can really do to stop print degradation. And it's cheap. Stay tuned.

 

[Roy Sletcher]

Yes, there is. And it might be a lot more than you would imagine. Think up to almost a 1/4 teaspoon per sheet.

We all know that humidity is hard on dye inks. Canon even makes a point of how their inks and papers keep images sharp by not letting the ink migrate. To say nothing of H2O being the universal enabler of chemical reactions.

The background: I live in Florida on the water. I have a digital thermometer/hygrostat and I'll estimate that the average, year round humidity is in the area of 70-75%. No AC in the summer which lowers the RH, all natural climate. The paper tested has been here for six years.

To find out just how much water can be in photo paper, I took 20 sheets of heavy 320gram? matte double sided paper, Royal Brites brand. I weighed them on my lab scale, 227.11 grams. I warmed up the oven at its lowest setting with a cookie tray to diffuse the heat. After it peaked and got down to 175F, I spread out the paper over some small bowls to maximize surface area. I kept them in there for an hour, periodically turning the oven on for 45 seconds. The temperature hovered between 150 to 190 degrees.

At the end of the hour, they weighted 214.97 grams. That's .61 grams per sheet! Or, to further check, that's 13 drops of water or almost a 1/4 teaspoon!

So if you have the habit of spraying your dye prints with any typical varnish, lacquer, or shellac, you are locking that water right in!

Some further thoughts:

1) So your paper has a polyethylene coating, front and/or back? First, the printable surface is outside of the PE, despite the forty year old urban legend otherwise. And PE is NOT a moisture barrier. Do this simple experiment: Take a rag or paper towel, thoroughly wet it. Put it in a PE kitchen bag, seal it with tape. In some weeks or months, the rag or towel will be bone dry. I learned this through attempts at cigar and print head storage. Doesn't work.

Therefore, if you spray your prints, do it front and back. After drying, of course.

2) Consider making a simple dessication chamber. I started down this road quite awhile ago, but now I know I will use it! I got a pound or so of silica gel at a hobby store for about $10 and a terrarium hygrometer for about $3 on eBay. A cheap plastic kitchen drawer silverware divider and a giant Ziplock bag completes it. Put the silica gel in the divider, put it into the big Ziplock, lay a paper towel over it to keep the gel off of your paper, put your paper in, and lay the hygrometer on top. Yes, in theory per #1 above that ziplock is not a perfect moisture barrier, but with all that gel and the hygrometer, it would take years to make a difference.

3) I would suggest keeping your paper in the chamber, printing, and then when dry to the touch, put it back in in order to remove any moisture from the inks still within. At zero percent RH, which is attainable, I'm guessing that a day should be sufficient.

4) Even if you live in a desert environment, typical year round average RH is still in the 20%-30% range, all depending on specifics.

5) Consider printing, let dry to the touch, and then spray the back, let dry and then put in the desiccator. That way when you go to spray the front, there is no time for humidity to get back into the paper. BTW, lacquer dries almost instantly, shellac not far behind, petroleum based varnishes the longest. I would go for several coats of shellac or lacquer.

My next archival post printing project could be called, "Beyond laminating and sprays." Why they bring their own problems and what you can really do to stop print degradation. And it's cheap. Stay tuned.

Interesting!

Generally commercially made paper will be designed to have about 8% moisture content and be somewhat balanced or inert at 50% relative humidity.
Moving outside these parameters could lead to other other problems such as wrinkling, distortion, retaining static electricity, dimensional instability, and a whole host of problems best avoided when trying to process the paper under controlled production conditions.

Further complications are added by the additional treatments and coatings applied to the surface to make the substrate printer friendly.

Now back to my dessication room, if my wife will let me have one. I will trade the threat of creating one for some space for a proposed Pro 10 this summer. Hopefully.


RS

 

[Paul Verizzo]

As you've probably gathered by now, I'm sort of fearless in the "Try it, see what happens," sense. Nothing blew up, the paper prints just fine. I think that locking in over a half gram of water canNOT be a good thing, at all. Ever.

Front side coating, I'm discovering, have serious problems. I've been experimenting with Krylon Archival UV acrylic varnish, simple Delft lacquer, and so-called clear shellac for coatings. Also a UV inhibitor made for fabrics, mineral spirits based. Other than the latter, every coating introduces some image degradation. Loss of contrast (I think), loss of detail. "Clear" shellac still has some yellow in it.

And I don't see any indication thus far that something like the Krylon really inhibits UV, at least with just two coats. Of course, any coating will stop gas fading.

My test image is a tile of four of my combined color and B&W test image. That gives me one quadrant of naked image, one quadrant of UV blocker only, one quadrant of UV blocker and whichever spray I'm testing, and one quadrant of spray w/o UV blocker. In one simple glance, you can see it all.

Don't stay in your dessication room too long. Plays hell on your skin unless you are well moisturized before entering.............