One of the better notions of gum printing is simply knowing when to stop. The flip side to that has to do with never ending the quest for the best marriage between the sizing on the paper, and the gum solution mixture. Since I began printing forty years ago I have always mixed my own gum from raw crystals. The days of easy reach of high grade gum crystals seem to be in the past. Now, mostly powdered gum or premix is the primary choice. Although, the crystals can be found, but not the clear crystals of the past. There is a slight amber cast to the gum mixed with crystals from the different gum batches I have.
My gum solutions were historically 50% gum/H20. In the past year I tried out the pre-mixed gum, rated at 14 Baume, and after extensive searching I got something of a conversion to % solution. Turns out to be approximately 35%-37%. I had originally thought that to be a bit thin, believing the thicker gum might aid in light penetration through the many color layers. Turns out, that's not valid. I have been getting very good results with that gum viscosity.
What that change demands is a reciprocal alteration in the paper sizing. The thicker gum remained on the surface of the paper better than thinner gum, using the same sizing. I used to size in 2 1/2% gelatin, twice. That, using the 50% gum solution. That was slightly overkill though. I have just prepared new sheets of printing paper for the next gum prints, using Fabriano Artistico paper sized with 28.5% gelatin for a full minute at 115 degrees. I am thinking this combination will make a good balance for keeping the image closer to the surface. The Tulip prints go to show how an image can be a full toned image, but sort of 'falling into the paper' softness. For some images I don't mind that. Capt Jack was one such image.
Upcoming print images are "Room into the Sky", an image from the Mission at Tumacacori, Arizona, filmed some years ago. One thing that remains constant, is that ci continue to learn the finer points of technique in making gum prints, with all the years I've spent learning this craft.
I have recently added a new section to this book, covering advanced techniques, using the five primary control variables for making a gum print. Ten pages that add to the other material in the book; mostly focused on the process.