Introduction and question: plaster curing time?

[Anonymous]

Hello, all--

I've been lurking a bit here and there and figured it's finally time to introduce myself. Several months ago we purchased our dream house and are going along bit by bit with getting it back into shape.

One of the first things is to do some plaster work--not just patching, since in some places we will likely be chiseling down to the lath and out until we hit sound plaster, then will be bonding the old with the new.

How long should lime plaster (no gypsum, I don't think) cure before being painted? And for how long should it be misted to prevent it from drying too quickly and cracking excessively?

Many thanks,
GMM

 

[Anonymous]

If you need a chisel the plaster to remove it, it is sound enough and doesn't need replacing. Only remove what you can take off with bare fingers.
Right then, that's reduced your workload. It shouldn't crack. Well, the base coat might and the next coat fills the cracks so that's not a problem. With the thin final coat squeeze the surface hard after a few hours to discourage any little cracks developing. Misting depends on the weather. The slower it dries the stronger it will eventually become. If you are painting with limewash or something similar then you don't need to wait long as the plaster can continue to dry and absorb CO2 through the decorative layer.

 

[Anonymous]

GMM
If plastering with lime it will take quite some time to completly carbonate , however as Biff mentioned you can lime wash over this. The cracking that may occur will be filled in with the wash , hence the self healing properies of lime.

I would not suggest plastering in the hight of summer , traditionally it was carried out in early summer. That was to ensure it did not dry out to quickly. Misting is a good idea , however hanging wet cloth in front was also used to ensure humidity.

Good luck.

 

[Anonymous]

Most I'll be able to get out by hand (it's quite spongy in spots) but I may have to break out the chisel here and there--in cases where it is not well keyed enough but stays up because of the hair binding it together.

I've been toying with the idea of using a limewash.

I'm still having a difficult job of it trying to find an answer to the question of curing. Do I use the "matchstick" test for all three coats, or is that just for the finish coat? Is one week sufficient time per coat, in a moist-ish and not overly warm or overly cool environment?