First, on your paper mark of the area in which you will be applying the emulsion. Traditionally gum emulsion is applied to be larger than the area of the transparency. This gives the print that iconic painted looking border. Always use pencil as pen ink will bleed during development. I simply put little dots at the corners using my ink-jet negative as a guide. (We will be making those in a later section don't worry)

You need make a choice of color and squeeze a little "worm" of watercolor paint into your tray. I am using Charcoal Gray here and making a worm of pigment about 1/4 inch or so.

Often I use more or less pigment depending on the circumstances. The less pigment you use, the more transparent the layer will be, and the less likely staining will occur. A thin emulsion also exposes evenly by allowing UV light to transmit through it.

Then you will add equal amounts of gum Arabic and Ammonium Dichromate Solution so that the proportions are 50%-50%. Precision does not matter in gum printing so I just eyeball it. I make a little pool for each about the size of my thumb which is just enough to coat one print layer. Getting the right total amount just takes practice and experience.

Now take your mixing brush and stir it all together, keeping most of the emulsion together to keep it from drying. I tilt the entire tray and mix it along one side to keep it in a little pool. Be sure to squeeze your mixing brush in a clean area to get any excess emulsion out of it so you can use that emulsion too!

Next, get your sponge brush and load it up with emulsion. Don't worry about getting it all on the brush, just come back for more as you need it.

Begin coating your paper around the edges of the intended image area, then coat the middle. This helps you see the boundaries better as you are coating. Or, if you prefer clean edges, you can mask off the edges with painters tape. I prefer the iconic lively messier borders myself.

The paper may feel very dry at first. Keep coating and it will begin to feel smooth through the brush. If continues to feel dry, you probably need a little more gum arabic and dichromate in your emulsion to make it wetter.

Continue coating in overlapping vertical and horizontal strokes, getting the emulsion layer to look as even as possible. There will always be light and dark streaks from your brush. After a few passes, the emulsion should appear fairly even. When printing multiple layers, these streaks will blend to create a subtle textural effect I personally find pleasing.

If you brush with too much pressure the paper may begin to damage. Also when the emulsion begins to feel very sticky as you are brushing, it means it is beginning to dry and you should stop.

Finally, set your paper somewhere dark or dim to dry for about an hour or two. A low speed fan to circulate the air helps. Most uneven streaks from your brush will tend to diffuse out onto the paper, although some will always stay.