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Adding Detail to the Plaster Cornice

Bob visits with Ralph and the plasterer to watch them add details to the plaster cornice. The scratch coat is complete and the white coat is underway. Several types of plaster are combined and each batch is workable for only 5 minutes before it hardens. A template is pulled across the spread plaster to form the cornice profile.
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Adding Detail to the Plaster Cornice

  computer-generated transcript - may not be 100% accurate

" -Now that's the scratch coat that we put up two weeks ago right?"

" -That's right."

" -We've got the scratch coat up and we've got the brown coat run and we're ready, we got a track set, we're ready to run the run the white coat."

" -We're gonna pull the rest of the corners work by hand, right?"

" -That's right. We've got a mold set up and we're gonna pull it, the profile of the corners."

" -Hi, Ralph."

" -Hi, Bob. Can we take a look up there?"

" -Certainly."

" -Now, this is not the kind of job that you're gonna attempt with a dry wall joint compound."

" -No, Bob. It really takes a special mix as you can see,"

" -Ralph is taking a lime, which is a lime putty that's been mixed with water and slake and he is filling it up as much water as he can hold between it."

" -And then, what's being added now?"

" -Now, he is adding gauging plaster and it takes 3 mixes, 3 parts for the mix. This is gauging and then they'll add molding plaster. "

" -And what are the differences between gauging and molding plasters."

" -Molding plasters sets up very quickly and it allows you to put plaster up and run it and have it set but,"

" -by itself it would set too, too quickly, so the gauging will help retard the set and the lime will help it give it some bulk filler."

" -Okay and we're restoring a running length of the corners that's about maybe 6 or 8 feet."

" -Right."

" -This is a small batch, why is that?"

" -Well, you can only run so much at a time. This will work for 5, maybe 10 minutes at the most and then it will be too hard to work with."

" -Oh boy, so that's a very, very span of time."

" -Right. You got to be quick. Once they'll get this mixed up, all thoroughly mixed then they've got to get it up on the wall and pull the forms."

" -Ralph, that's the best way to mix it, so as you don't get bumps and stuff in it."

" -Well, yeah because you, you get dry spots in it if you try to mix it in a bucket usually."

" -Aha."

" -In this way, you can work it in and you can adjust the amount of water you use so the thickness or you know you have a certain amount of control over it."

" -What, how many parts for each?"

" -Ah, this is a 5 parts lime to 4 parts of molding and 2 parts of gauging."

" -Okay. So you don't overload the hut and you spray some water on the, on the scratch coat before you approach it."

" -And the water will help it, so it doesn't set too fast."

" -Can you just do 3 or 4 feet at a time or can you do a"

" -That's all you can do. You really can't do too much at a time just because of the nature of the material. It's as much as you can spread and then pull."

" -Gee Ralph, that's really something. It looks like a 10 year old did it."

" -I'm loading up the wall"

" -and Jack will pull the [unk] in a moment."

" -Yeah. Pulling it is the secret because you end up with a very, very fine layer of plaster. Let's look at that. Moby, did you make this up?"

" -Yeah. Well, actually we've made a wooden form and then cut a metal profile of the cornice and it's got a handle on it, so, it'll, you can hold it comfortably and run it in on a wooden track."

" -So, you've copied the existing cornice. "

" -Right."

" -Okay."

" -Jack will wet it and go ahead and start to run it now and see how it works."

" -Knock yourself."

" -Yeah."

" -Now you can see, it's not perfect the first run. So, what they're gonna do is run it a couple more times and they'll add some more mud where they need it."

" -Where there's a void."

" -Where there's a void and gradually it will build up with the profile that we want."

" -Alright. We've have about a half an hour elapsed in real time and this is the third pull with that profile screen and you can hear the plaster, it really has dried up."

" -This is a lime slurry I'm adding to fill in any air bubbles or imperfections in the pull."

" -The original cornice and frieze is highly decorated in this house. There is a row of small {unk] sleeves here. There's larger [unk] sleeves over here and this is the part that we're reconstructing. Underneath every couple of feet or so, is an element called a triglyph which comes from Greek temples. Down below there is a frieze that's decorated with these horns of plenty. Spilling out with fruits, [unk] and rice and it is a complicated restoration project you've got here."

" -Right now, you're ready to put up, what? The, the big"

" -The larger [unk] sleeves have been already marked out where they're going to go and"

" -You've made about a hundred of this haven't you?"

" -Yes with a rubber mold. I think you saw that already."

" -Right and how, how do you put them on, with glue or something?"

" -I use a plaster of Paris to attach this. It just takes a little bit on the back of each one."

" -So, the plaster of Paris is the faster setting plaster, right?"

" -Yeah. It is very fast setting and it just takes a little dot and we set it and hold it for a few seconds and it will be there permanently."

" -Okay. Here's another one. It's a little bit like decorating a cake. Isn't it. This is a replica of a triglyph."

" -Right."

" -And you have to hold that or should I put it out here?"

" -[unk] just put it a small thin even coat."

" -There you go, cream cheese."

" -And we have that marked off like those right there."

" -Just like his days of old."

" -Hold it for just a couple of minutes and it will be set."

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