Sun damaged orchids
 

It got to almost 105 degrees two days in a row and since I was working a lot, I didn't notice the affect it was having on my orchids. One of them, a miniature phal, has yellowing on almost every leaf now, but the leaves aren't shriveled. My dendrobium also has slight discoloration in quite a few leaves (just a lighter green).

I'm guessing there's no way to actually REVERSE the damage, but I was wondering how I could prevent it in the future. I have a sheer curtain on the window I keep my orchids in front of. Would closing that be enough on hotter days or should I actually move them?

All my orchids are by an east window.

No, you cannot reverse the sunburn, but ABSOLUTELY PULL THE CURTAIN. You might also consider moving them on days that you know are due to be intensely hot.

I have some orchids that get afternoon sun, and when I know it will be very hot, I move them. Better they get little light for a bit, than cooking them. Don't beat yourself up - it happens - I have a few times not realized how hot it was going to be and ended up with quite burned orchids.

How warm does it have to be for them to burn?