In this instance I also wanted them to look like this rather than the more familiar angled look.
And to be clear, this is better than straddling a corner at an angle because there's more material surface and more air behind. The only downside (not really) is it costs more (more material) and sticks out more into the room.
So, I'm confused... I thought rock wool came in a rigid sheet form? Yes, yes, yes I am a master of all that is construction. I'm sure Steve has more knowledge in his pinky than I have in my whole brain. Thanks for the illustrations Steve, they're very helpful!
Here in the UK Rockwool is just a trade name - it has a huge amount of variants. My favourite is Knauf - but my local stockist has stopped using them for some reason, shame but little I can do about it. Knauf 'Earth wool' is just so nice to work with, and smells of spun sugar. Additive free and no nasty chemical binders either - but it is a strange burnt colour, instead of 'Rockwool's' green shade. No problems with the images - I have a feeling there will be a few more on my other thread soonish.