Gum prints require that you use a substantial paper that will stand up to repeat soaks in water. Prints can be made with only one coat of emulsion, but most of the time you will find that multiple coats are necessary and with each coat the paper has to be soaked in water. Pure cotton papers can be very expensive, but well worth the cos. The less expensive papers will work just fine for gum prints and you will find that the cotton fiber papers offer better control over the emulsion and how it develops on the paper.

I have found that if I mask the outside edge of frame I get a neater edge, also when I apply the emulsion I use a plastic salad spoon to dollop the emulsion onto the centre of the paper. I use Schoellershammer Linen 225 gsm & 300 gsm, it handles my abuse of it’s surface quite well.
My paper is often stretched on to large oak tabletops which I bough at an auction when I was a student 25 years ago. I use brown packing tape, the type that you wet and apply.
I use a glass rod to spread the emulsion smoothly and evenly. If I want a more randon feel I then use a sponge or wall paper emulsion brushes, there is r4eally no limit to application techniques in my personal experience.
Once developed I coat the surface with a acrylic glaze which allows me to work over the layer with another exposure or work onto the surface with airbrush, sponges, brushes, even tint the surface with coffee which is much like chinese inks, by laying on layer by layer you can increase the density of the colour. I can erase some portions of the surface with a fibreglass rubber, the type that is used by architects beforte the days of CD and computers. I bought out the old stocks from local supply stores at one of their sales decades ago.
I also use a flatbed laminator, to flatten the surface and cure the image. If my flatbed is too small I then use an old steam iron.
I work very large too, because I work in a newspaper as a senior sub editor and photographer, I have access to very negative printers, and they are capable of one metre or larger continous film negatives.
As I use my own profiles I can control the neg outputs very accurately. All my negs are punched and pinned at the newspaper so that I can emulate the registration process at my home studio.
I expose using mecury vapour lamps even though we have an abundance of good clean and reliable sunlight in South Africa.
Once I have completed the image I either either photograph it or have it scanned using a large drum scanner. The digital image is then output digital once I have colour corrected and tweached the image through photoshop.
AS I do limited prints for boardrooms or family portarits I find the potasium dichromate allowsme an edge against my competiton and gives me a unique product at the end of the day.
I started this process mostly for editorial and annual reports when I worked as a commerical illustrator early in my working carreer.
I am now re-visiting the process as a fine artist and finding the process a huge amount of fun. The advantage of working so much bigger than the average is so that I can scan the image, reduce the image and finally when I output limited prints my images have a tighter grain with an even finish.
I often work on the edges of the images and my use of pigments span, water colours, gouche and acrylics, inks and house hold coffee and herbal teas.
For me the potassium dichromate image generates a base image which allows me to functions as a illustrator and fine artist.