Hi all, I'm a long time lurker who's just getting started on a Model IV build. Y'all's build logs and comments have been incredibly helpful thus far.

Anyways, I was washing out my right fuel tank today when I decided to peek inside. This is what I found:
5AE276A9-B82C-4FD3-A660-F67F19049359.jpg

Is that normal? There aren't any leaks but I'm worried there is serious delamination going on and that I need to toss the tanks. Side note - after washing it out with water, the tank felt warm to the touch and exhausted warm air. Would washing them out cause some sort of reaction?

Regardless, thank you all so much for any help beforehand. This build has been a lot of fun and I'm excited to get it in the air.

Will