I have no idea about "ratios."
I squirt a large squirt of Elmer's into an old plastc 35mm film thing, and then I add HOT water until I get it the consistency I want. It mixes better the hotter the water is, and it will take much LESS water than you'd think (if you're getting it too thin, just squirt in more Elmer's). You can make it any thickness you want, right up to a semi-gel. I like it about the thickness of thick enamel paint. Several drops of dishwashing liquid (I use Dawn if I have it) breaks the surface tension of the stuff so it flows well and doesn't leave bare spots, and also might help with it removing easy, I dunno, but it works. I add some red food coloring so I can see where I'm putting it. The red coloring will NOT leach or "bleed" out onto white paint--I've tested it.
I apply the stuff with a soft paintbrush, and then rinse the brush out immediately with hot running water--it comes right out. For things like airplane canopy framing, I put it on with a toothpick, and the stuff flows beautifully right up to the frame line. Lovely stuff to work with!
The batch I'm using now I mixed up about 2 years ago and it's still good. If it dries out or something, a fresh batch is only about 5 minutes away.