Scorched cacti

Three of my cacti have been scorched in the blazing sun of the recent heatwave. I have taken them out of the cold frame where they were situated and put them in a shady corner of a perspex shelter.
I don't suppose the damaged tissue will recover but I am wondering if there's anything else I should do to them.

Two of them are very spiny with lots of hairs and I thought such cacti could stand strong sunshine ... so much for what you read.

Here are some photos of the scorched bits that faced the sun. The other side of the cacti are fine.

 

That's a pity Michael, it will take a few years to grow out.
I think even with cacti they need to acclimatise, and when small they do burn, in nature they often grow in the shade of other scrub until they out grow it.
Might be worth checking for RSM, I had some rebutias do similar and on close inspection with a lens I could see them.
They seem to make that part of the plant more susceptible to the sunburn.

 

Thanks @pete I'll have a look.