Thistle undercoat plaster; manufacturer says if necessary to achieve the required thickness, build up basecoat in 11mm stages.
If applying the base coat in two layers, at what stage should the second layer be applied? Is it when the first layer has just become firm but not yet gone hard, i.e. when the first layer is at the same stage you would let a base coat get to if you were then going to apply a top/skim coat?
That depends what stage you personally would do that!
With bonding coat, I would suggest anytime between when it's set and when it starts drying. You don't want any chance of pulling it off or having the coats slump, and you don't want the first coat sucking moisture out of the second coat. Make sure the surface of the first coat is roughed up to provide a key, although bonding coat would probably stick well even without. If you do end up leaving it to dry, then you will need to PVA before doing the second coat.
Can't comment in the case of browning coat, as i haven't ever used it.
Andrew, thank you for the "what to do, and why" information. It was most helpful.
Regards
Anode.
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