Another plaster crack

FreshlyCutFlowers

Looking for some advice on next steps. 

I've stripped wallpaper of a wall with a steamer. Even being really careful with the steamer caused the plaster board to bulge out on two occasions. 
Once it receeded back in when cooling down but the other (pictured) became a long cracks that still bulges. When tapping in there area down and left to them tile (as far down as my hand) it sound hollow compared to other places.

What do I do from here? I've been told it's fine to just fill in but reading online it is seems I have to tear the board off and fill with plaster..?

Bit worried about it becoming a big job. 
I was going to wash, prime and paint it but plastering isn't something I have experience with. 

Thanks! 

grumbler

Is it plasterboard or lime plaster?

If the latter, it often loses connection with a brick wall and is held in one piece by wallpaper only. "Hollow sound" is usually an indication of some area disconnected from the wall

FreshlyCutFlowers

grumbler said:

Is it plasterboard or lime plaster?

If the latter, it's often loses connection with a brick wall and is held in one piece by wallpaper only. "Hollow sound" is usually an indication of some area disconnected from the wall

I fixed up some of the smaller cracks with tape and sealing up with filler. It seems like a really thin plaster board? Is it normally this thin? 

stuart45

12.5 mm is normal is walls, sometimes 9.5 mm is used.
6mm is for curved work.

grumbler

Isn't plasterboard white inside, not pink?

Can it be just pink gypsum plaster with poor adhesion to the wall?

Also, if it's plasterboard, the wall has to sound 'hollow' pretty much everywhere - except the places where the 'dots' of adhesive are behind.

Grenage

It looks more like heavily blown plaster.

You have two options, fill and hope for the best, or knock it off and get it plastered.

Generally if the plaster doesn't move when given a bit of a press then I'd just fill and sand.  Blown plaster is common and not always an issue if you down need to put something on the wall.

fenwick458

looks like a job for a plasterer. you'll have to knock off all the loose stuff off, prime it and then skim it.
this is the reason I hate wallpaper steamers; they are slower than just soaking the wall with water and scraping it off, and they blow the plaster off