REPAIRING CORNICE!!! plaster of paris mixed with lime putty?

[drummer_boy]

Hi folks,

A big thank you to everyone who helped me with my last post (especially Nigel)

I now know how to make a lime putty in order to fix & repair my damaged cornice, but do i need to mix NEAT plaster of paris with the lime putty? or do i make up some wet plaster of paris 1st?.............................................again i think its a 50:50 ratio?

i know.......it's probably a silly question, but only fools rush in!?

oh, p.s. how long will this mix take to go off?

once again, thanks in advance!

Chris. aka drumm_boy

 

[Nigel Watts]

If making a small batch I usually form a ring of lime putty on my improvised plastering bench (an old bit of melamine kitchen worktop on two tressles) - rather like a volcano crater. I fill this with water, sprinkle on the Plaster of Paris, then mix the whole thing thoroughly. If you put the plaster of Paris in dry the mixture may get too stiff.

The resultant mix goes off in about 10 minutes, but the texture changes as it does so from thick cream to stilton cheese. When applied to the ceiling it can go off quicker as a result of the suction. You will need to exeriment a bit to find out what works best.

For forming the straight mouldings it is helpful to have the right tools. What you need is a few different sizes of what I believe are called joint rules. These are stiff strips of steel about three inches wide, with one bevelled and ground edge, with a 45 degree end. They come in a variety of lengths.

I have had no tuition in this but have acquired an acceptable level of technique through trial and error for making repairs. An expert will no doubt be able to give you better advice.

Good luck

Nigel