It has to dry slowly to crystalise properly. Hanging damp hessian over the freshly painted wall is a common practice. It's the same when using lime mortors, yo

It has to dry slowly to crystalise properly. Hanging damp hessian over the freshly painted wall is a common practice. It's the same when using lime mortors, you are generally looking for a three day cure for mortor. Lime does not like the sun, wind, or rain (basically any weather!) during this time.