Not seen this before

[Donzo]

about 3mm thick,, ,it looks like ply, with holes then skimmed over.
Other side has artex to be skimmed.thought plaster on ply don't go,even with holes.

 

[Casper]

Hardboard.

 

[Kinkyboy]

Holes=@tapit

 

[essexandy]

That's definitely hardboard, the type often used in shops. The shelf brackets went through the holes.

 

[Mouldyoldspudgun]

Yep hardboard defo

 

[Casper]

Thankyou

 

[Jbeesy718]

Called pegboard usually has a thin laminate on one side.

 

[tapit]

about 3mm thick,, ,it looks like ply, with holes then skimmed over.
Other side has artex to be skimmed.thought plaster on ply don't go,even with holes. View attachment 53303

The holes act like magic for plaster. I think you have found one of my early prototypes.

 

[paulf]

The holes act like magic for plaster. I think you have found one of my early prototypes.

The holes are small enough for a tapclit gloryhole.

 

[stuart23]

The holes are small enough for a tapclit gloryhole.
View attachment 53357

That’s bigger than mine

 

[paulf]

That’s bigger than mine

Never mind that look what I found.