Air bubbles can be avoided by using a container with a hole in the bottom; then, the bubbly part comes last and you can discard it.
For example, I have used a 35mm film container with a hole on one side just at the bottom. This holds about 25 ml of emulsion, which is probably enough for 4x5" plate, or even bigger, I think. Pour the emulsion in the container while keeping the hole shut with your finger (use gloves), wait for a minute or so that the bubbles go up, then coat.... This has worked for me.
Some people have reported squirting a little bit of ethanol on the top of the container to remove bubbles. Denatured might not be good for this.
Also, I don't think you need to sub glass plates with gelatin beforehand. Try to coat as is. It should spread on a clean glass.
If the adhesion is a problem (do not process over 20 deg C or so, anyway), you might need to add hardener to the emulsion and stir well just before coating. Chrome alum, glyoxal or formalin may do the job. Search this forum for more info.
Last edited by hrst; 04-25-2012 at 06:51 PM. Click to view previous post history.