How long for crystacal R before I can paint it?

[Daveum79]

I'm using crystacal R for some castings that I then need to paint but have a relatively quick turnaround time before sending these out to customers. Can I still paint these say within 24 hours of casting or am I supposed to wait days before painting then applying polyurethane varnish? I do notice that when I first cast and sand down the plaster is a slight greyish dull colour on the areas sanded but over time the plaster becomes more of a natural off white colour therefore I'm not sure if I'm supposed to wait until this state before working on it but I really can't wait a number of days for each piece as what I'm doing isn't going to be practical that way in terms of time, so just wanted opinions on how long one waits for plaster before working on it.

 

[valiant]

You cant really paint it until it is completely dry, otherwise the moisture will effervesce through the paint, destroying the finish. Ideally, you can dry the casts in an drying oven, but it needs to be vented to allow the moisture out, otherwise it creates steam. If the plaster appears off white, there is moisture present. It will be chalk white, when dry.

 

[Mirofsoft]

Plaster must always dry
According to the thickness, it can take weeks

 

[arj]

Second paragraph down confirms the above statements:-
https://www.justpaint.org/painting-plaster-with-acrylics/

Cheers,
Andrew

 

[Mirofsoft]

Famous exceptions

Wall fresco ; all is in the term "fresco" ( fresh), painted directly without waiting for drying .