Hi Bill
Question for you. I had the most succes following your ideas about coating canvas, so I would love to pick your brain about coating paper.
When I use Timeless or Polycrilyc on canvas I dilute about 25% water and 75%coating, multiple light coats, normally 2 or 3. Most of the time I add a tiny fraction of a drop of dish soap to the mix, seems to help the coating to level. The result is a really smooth and even satin, very pretty.
Do you dilute on the same ratio when the print is on a paper like the Epson Hot Press ?
Do you tape the sheet all around to avoid curling after the coating dries?
How long between coats?
How many?
Any other difference on the way you treat fine art paper compared to canvas?
Thanks a lot in advance
Hugo
For the fine art papers I have been diluting 1 part water to 5 parts paint,
measured by weight. So I might mix up 500 grams of Polycrylic to 100 grams of water. Grams and ml are the same thing for water, but the coating is denser and might weigh 1.1 grams per ml. I find it very useful to use a scale for such measurements, there are many advantages to that, including that you don't need measuring containers which have to be cleaned. That dilution easily sprays wet, and since the concentration of paint is higher one gets more coating effect for less work. I think maybe 1 part water to 9 parts paint would be the limit for what I call good spraying characteristics, using my gun and turbine.
I usually make ganged-up prints 44 x about 80 or 90". In that case I first put a 3" swipe of 1" tape in the center of each of the 44" sides, to flatten out the print across its center. Then I completely tape down both of the long sides, which is made a lot easier by the already in place 3" tapes. It's really just the long swipe of tape at the top that's important, since it keeps coating from getting on the back of the paper. The long bottom swipe of tape is to prevent differential shrinkage as the print dries, which could cause minor keystoning. To accelerate drying I often remove the bottom swipe about 1 hour after coating, while the print is still mostly vertical. To minimize the small amount of keystoning that might occur, I also remove about half the swipe of tape at the top, leaving some at the center to support the print. There's much less tendency for paper prints to keystone than canvas. I mount the prints as early as 4 hours after coating, there isn't much curl to deal with at that point. But if want to leave them completely taped up for a day or more your will get very flat prints.
In my dry desert air I usually wait about 30 minutes between coats. I test dryness by touching the tape, which dries much slower than the print surface. If you get little flakes of coating that crack off when you later cut the well-dried prints, or you if you get excessive curl on the dried prints, you probably should wait longer between coats.
I usually apply two coats, putting down about 10ml of by 1:5 solution per each coat. I weigh the gun after each coat as an ongoing QC thing, leads to very good consistency and avoid long term process drifts due to gradual changes in filters, residue build-up in the gun, etc. I have a few pieces that present better with a more matte like look that comes from 1 coat, and a few that look best with the very wet glossy look that comes from three coats. Of course, when laying down one coat you need very good technique to avoid banding.
The main difference in handling fine art papers versus canvas is that you need much more glue for mounting, especially if the print still has some curl. The moisture helps de-curl the print, buy you must have enough moisture available to wet the print enough to at least partly relax the curl, and to be certain there is still enough wet glue to attach the print at the edges when the curl is gone.
