I can only make that lame joke in the title of this project log because RedGard goes on pink and dries a fairly dark red. RedGard is a paint-on liquid waterproof membrane. Technically, since I am using GoBoard and approved sealants for the seams and fasteners, I don't need to use something like RedGard. I'm doing it anyhow, for extra confidence. (And also because I bought a gallon of it for doing the test wall before I decided to use GoBoard.) This stuff is pretty expensive, and a gallon is the smallest amount that you can buy.

Even as an extra confidence factor, I only need to put RedGard on the seams and fastener locations. GoBoard surfaces that are intact are inherently waterproof. The drywall above the GoBoard doesn't need waterproofing at all since it's outside of the wet area. I put RedGard on it for a different reason. For setting tile, the convention is to use mastic on drywall, especially painted drywall, because thinset doesn't adhere to it very well. The coat of RedGard solves that so that I can use thinset all the way to the top of the wall. If you do web searches for using RedGard on drywall, you'll see lots of advice about not doing it. But that sort of advice is really telling people to not use drywall (or the drywall and RedGard combination) in a wet area. In my case, I'm tiling over the drywall for aesthetic reasons.

I did most of this with a 4 inch roller, which I was able to dip directly into the RedGard container to load it up. In the corner seams, I used a 3 inch  paint brush (the cheapest model I could get).

I need to use at least two coats of RedGard. As I write this, I'm waiting for the first coat to dry. It looks like after the second coat I will still have more than a third of that gallon of RedGard left. I might put on an additional coat just because of that.

This photo is after the second and third coats and a couple hours drying/curing time. It turned out to be about half a gallon left in the bucket.