From what I remember in chemistry, sunlight can speed up the reaction. The stuff does take pretty good, the stud I used wasn't extremely white, but still pretty light. It still took it pretty good. So if you're leaving it to react that long, you might only need one coat. Is your stuff spruce/true whitewood or yellow pine? Like I said, the coffee didn't make much of a difference from what I could tel earlier, but I'm going to check it back out here in a minute since it has dried some more.
I'm going to take pics in a little bit. Are you talking about pictures of the wood or of my jar of mixture?
Sorry I didn't see the coffee part.
I'd like to see what color the mixture turned the board without the coffee.