White BOC is now creasing? DIY what did I do wrong?

I think I may have skipped over a step or maybe I read the process wrong for making my own screen?

Laid out a wood frame with a center strut. 85" long and 55" wide with the center strut at the 44" mark. Then stretched some black out cloth over the frame and stapled it to the outside edge ( my wife held it to the frame and I stapled down). Then with the 1" remaining, I wrapped around the back and stapled again.

It went into my basement fine a week ago, but 3 days ago a crease appeared and then today I have 3 more? Did I skip a step? We have a dehumidifier in the basement so moisture isn't an issue. That fabric was super tight when we originally stapled down but I guess its getting loose.

Do I need to:

- Re-Wrap the BOC?
- Maybe spray the BOC with water and let it tighten up?
- Or do I need to paint over the raw BOC to make it thicker?

Also, I have enough fabric to do it again, maybe I could just wrap the new BOC over the old stuff and staple down again? This would make it a two-ply and be the easiest option.

Any help would be appreciated. Thanks to everyone out there for some much chatter on this.

We really stretched it tight, but with the re-wrap it's even better. I'm able to get another 1/4" of stretch now, and re did two corners. Wasn't bad at all, screwdriver to extract the staples and two cold beers.

You are a wealth of information and very helpful to us noobs. Thank you.