Re: home made spreader/sticker to make sprays rain-fast?
I used to use an egg yolk spray to keep the deer away, but as you say, the rain (or fog in my case) made it less effective.
I put a few drops of olive oil in a hand sprayer and a few drops of hot sauce. I separated the whites from the yolks because they clog up the sprayer. Then I mixed the yolks with water and strained the yolks into the sprayer, because they had clumps that could also clog. Refrigerate the spray bottle between uses. There is a chemical in the yolks that mammals don't like, I forget what it's called. It's not just the rotten egg smell.
If the whites are a good glue, maybe making a separate spray out of them would help. I never tried it, but it sounds pretty good. And you've probably noticed, the deer don't stop going into the garden, they just don't eat. But they are always testing, and enough moisture overnight and bingo, they eat!
And because I have rabbits, raccoons, mice that also eat the veggies and fruits, too, I ended up fencing the perimeter, and it's the BEST thing I ever did! The expense is not too bad if you do it yourself. I did have some trouble with the birds not seeing the chicken wire at dusk and dawn, so I ran a line of colored construction string around the very top, and that has worked so far.
"Life flows on within you and without you"...George Harrison
Coastal California, USA, Mediterranean climate - no summer rain, a little frost mid-winter