Gum Printing FAILURE

So i was trying this new printing method that caught my attention.
Gum Printing; which is basically Arabic gum and ammonium and the sunlight as my light source.
I used an old 4x5 negative, green watercolor, regular white cardboard. It was a complete failure cause:

1. clouds were blocking the sun all the time
2. maybe the cardboards needed another layer of the solution.
3. my ammonium mix might have been too weak.

Overall it was fun, i love this method, but i need a stronger light, so im probably gonna bet a uv light box, if not, then i will try the potassium mix which is the same thing but it's sensible to any light.