Skim onto ply board ?

In the photos it shows a ceiling which has been covered with artex paper.

I have removed this today and underneath you can see a layer of chip paper i think.

Everything is very loose and i will be removing all of this tomorrow with a steamer.

Underneath the chip paper you can make out what the ceiling has been boarded with and it doesnt look like PB. I think it is ply board.

So my question is, can i skim this ceiling ? If so would blue grit be best used over PVA.

If i cant skim it, do i have to board it out.

Ive also been watching some videos on doing a magic mix. Bonding plus multi. Could i use this mixture ?

 

Just pick the surface of the board with something sharp to check because some older PB was very brown. I took some down here that the paper alone seemed stronger than the modern stuff, pb that is

 

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The ceiling is an older PB. I am just reboarding in 9.5mm tomorrow.

thanks all for the info.

 

Im not a plasterer so cant say if its necessary but when I overboard and where possible space the new boards so they overlap the old board joints.