With all this dry heat we are having in the Southwest, keeping one's paper moist while printing moku hanga is a challenge. I have developed my procedures to account for the dry air. I have never had the benefit of printing in a humid environment and so may have to relearn or adjust much of what I do if I ever print in an area with high humidity.
My studio has large doors which allow a nice breeze to flow through the studio which can quickly dry out the paper. So, after the paper has been moistened, I take care to keep it covered. Some papers will dry out very quickly such as an Okiwara 60g. Once a paper starts to dry out, printing will become problematic and the ink will transfer unevenly.
Each variety of paper requires more or less moisture depending on the thickness or sizing. I have some Japanese hand-made paper from 1900 which has minimal sizing and so absorbs moisture quickly. Where as, a machine made paper such as Shiramine needs far more time to absorb moisture and be ready for printing. traditionally, paper will sit in a damp pack for 6 to 8 hours.
Once printing begins, I make sure the paper is always covered with a plastic sheet. For easy access, I tape a strip of foam core along the open edge of the plastic wrap so I can easily access the moist paper and slide the printed sheet under the plastic. I make sure the wrap is large enough to extend beyond the paper edges, holding in the moisture.
Depending on the size of the paper, there are two options to use. The first is a side by side layout. This needs more table space and is an easy set up. The other option is to create a bi-level wrap where the paper to be printed is on the lower level and printed paper is placed in the upper level. This option is great if there is a shortage of table space which is often the case.
Ink formulas can be very personal and have usually evolved to match one’s own personal preferences. Some folks add rice paste to the mix while others apply it to the block. I add the paste into my ink mix. For my colors, I use Mixol pigment pastes to create my color mixes. The colors are light-stable and are very intense which means a few drops will create a strong color.
My one secret ingredient is glycerin which slows down the water evaporation. Just a few drops will help keep the ink moist on the block. Glycerin is available at most health food stores.
When inking the block, I am always looking for that perfect balance of moisture between the paper, the brush and the block. I think I have my ink mix a bit wetter than a traditional mix. I often start printing by rubbing a small amount of rice paste onto the block and then wiping it off. This makes the block hydrophilic allowing the ink to spread out evenly. When brushing out the ink layer, bubbles are a sign of too much water. I blot the brush onto the towel to pull the extra moisture out. Blotting excess moisture from the brush will then allow it to pick up the excess water off the block, getting back to that perfect balance of moisture between brush and block.