Try Vasalene Hair cream instead of brylcreem. It is a white creamy derivative of Vasalene petroleum jelly. It may melt if you don't seal, but your camera will smell nice, and you will look less like the Fonze with a little in your hair.

I thought I had posted this already but must have only thought about doing so.

Xylocaine (R) 5% Ointment. (Not the 4% which is too thin.)

It is a stiffer brew and does not seem to separate or crack like some of the emulsions when it is squashed into a thin layer between two glasses. I don't know how it goes long term. I dropped my microscope slides and one prism which got chipped. I was not happy. (Fortunately the prism is chipped outside of the 4:3 image area so I can still use it in the vertical plane.) The only slides I have left now are groundglassed already from other tests.