What primer for tiling on plywood

[Michaelsf90]

My walls are plasterboard dot and dabbed on brick and a plaster finish. I have mapei plaster primer for those. I also have to tile on plywood. Which is the best primer? Could I use everbuild sbr bond? Would sbr bond be better on the plastered walls? It says mapei plaster primer is water based whereas sbr creates a rubber/acrylic seal. Or should I use bal sbr on the plywood and mapei plaster primer on the plastered walls? Thanks

 

[Swwils]

Is this plywood on a wall or floor?

 

[Michaelsf90]

On a wall. I know it's not ideal but the tile have been there 25 years previous. Our new bath is now also fitted so it's too late to change

 

[opps]

I would go with dilute SBR for both.