Mixing plaster with marble dust

[paulc]

Is there such a thing as a correct ratio for mixing lime and aggregate for plaster work ?

I have several bags of crushed Carrera marble ranging in particle sizes from <100 microns up to 500 microns. Planning on using this as a finishing coat during the renovation (replacement) of a 1920s lath & plaster ceiling.

Would a 2:1 mix of marble & lime putty be suitable or should I go for a 1:1 mix ?

 

[MatthewC]

Hi Paul, welcome.

I would check out what the various manufacturers say - from memory Mike Wye have fine plasters which are 2:1 but they also do even finer ones that I haven't used.

Matthew

 

[paulc]

I had been looking at the Mike Wye site - The fine finishing plaster is listed as being a 3:2 mix of sand & lime, but nothing is mentioned about the regency or venetian plasters. The latter I suspect is a 1:1 mix (it definitely cracks and flakes off if applied too thick).

To start with, I've mixed a batch at 2:1 and smeared a bit on to a scrap of plasterboard. It goes on fairly smoothly but looks awfully grey as it dries.