Actually I might know a solution to the drying out of retrobright by adding in an extra ingredient to the mix, but I'll need to experiment with it first. If it goes well I'll make a video.
That would be legit if you could find a way for the retrobright to not dry out without using saran wrap. Please keep us posted with your findings!
Any luck yet I have theory too
Nah. I tried vegetable glycerine, which essentially would've been like adding oil to it to keep it from drying, but it didn't really work. Chances are I used too little, or it was because it was like 95 degrees. I'll try again and let you guys know.