Overlaying multiple textures in Blender

In 2019 I made an internet artwork for Fermynwood’s programme Toggler.

For this work I decided to use a similar aesthetic and process to Visually Similar. I talked a little bit about the process behind Visually Similar in a June’s Development Update. The node tree to overlay each of the transparent textures looked a bit like this.

Click to embiggen

When trying to do the same with the Toggler artwork I came across something weird that meant some textures just weren’t showing. So I decided to ask on Stack Exchange and Reddit why this might be the case.

Click to embiggen

It looks like I wasn’t using the alpha channels properly and didn’t need to use the Add math node, or just needed to use it properly. If were to apply the same process retrospectively to Visually Similar the artwork would look like this.

Curiously several of the textures didn’t show up. I suspect that doing it this “proper” way revealed that I had the order of the nodes incorrect. If I show the work again I’m might edit it so it looks “right”, but in this case the mistakes yielded a more preferable result.