Black out blinds

We have the tommee tippee black out blind and ive put a bit of velcro just under the curtain pole and then stick it up every time its used i felt like it was a real faff to keep it stuck tk the window and to actually block the light otherwise x

We have those and also have victorian sash windows and it was fine for us, but the suction does get strong, which it should as they're quite heavy. But if you break the seal with your nail and don't just try to pull it off forcefully I think it should be fine?

thanks for your replies, it seems that it doesn’t actually block out all the light?

They don’t fully block out the lights as the gaps between the suction cups are quite large so it would make sense to get the Velcro to stick on. We used 2 sheets for our windows as they were quite large. But now we just got custom blinds. You can check blinds2go they do fully black out and they are not as expensive as going to a curtain or blind shop

We have one and weren’t rolling it up/taking it down during the day and our window cracked. We assume due to the heat caused by the blind.