Replies

1. 
   andybuildz | Jul 08, 2005 01:57pm | #1

   David

         Beautiful job!

   Thing about prefab is its quick and as they say, time is money...but it's nice to see someone still taking interest in using their imagination and oatience.

   Great job.

   Be well

   a..

   The secret of Zen in two words is, "Not always so"!

   When we meet, we say, Namaste'..it means..

     I honor the place in you where the entire universe resides,

   I honor the place in you of love, of light, of truth, of peace.

   I honor the place within you where if you are in that place in you

   and I am in that place in me, there is only one of us.

    

    

   
    

    

2. 
   dIrishInMe | Jul 08, 2005 02:18pm | #2

   Nice - how did you make the trim?  Router on some kind of compass apparatus?

    

   Matt
1. 
   user-53610 | Jul 08, 2005 06:51pm | #6

   Yup, I used a scrap piece of 1/4in mdf and a roofing nail to do a compass. I've only got about 5 router bits so I had to get sort of creative and do multiple passes with different bits but it came out ok in the end. I've done other projects that required a lot of odd shaped router work for which I used templates (http://www.kondra.com/booth/booth.html), but I find that it's almost more work to make the templates than to cut the final pieces.

1. 
   zendo | Jul 08, 2005 07:24pm | #7

   David,

   I didnt take the time yet to read your article, but a few weeks ago there was a pic in the photo gallery from a regular who used an old mesh satellite dish that he told an owner he could get rid of, and framed it into the ceiling... it was large and very cool.

   -zen

1. 
   user-53610 | Jul 08, 2005 07:41pm | #8

   > ...from a regular who used an old mesh satellite dish...Frankly, I spent a bunch of time looking for something along these lines to make things easier. My original plan was to look for a planter pot or wash basin of the correct diameter and then stretch plastic over the top and use a vacuum to get the curved surface and back fill with foam. In retrospect I don't know that it would have worked as well so it's just as well that I couldn't find anything big enough to try.

3. 
   CloudHidden | Jul 08, 2005 02:26pm | #3

   Very nice. Along with finish plaster, consider the 20-minute or 45-minute joint compound. Ease of joint compound without the long dry time.

1. 
   MrJalapeno | Jul 08, 2005 05:39pm | #4

   David,

   Nice!  I'll take one.  Nice presentation too.

4. 
   JeffBuck | Jul 08, 2005 06:35pm | #5

   Impressive!

   nice project ... great end result ...

   and very nice article.

   Jeff

       Buck Construction

    Artistry In Carpentry

        Pittsburgh Pa

5. 
   msm | Jul 08, 2005 07:53pm | #9

   incredible! great job!
   love your ingenuity developing your sanding tool/template! thanks for posting the method AFTER the teaser showing the perfectly sanded foam... i tried to guess how you did it but didn't come close.

   trammel points on a ripped down yardstick was a gift from my dad that i use often for large circles. so fast to adjust size accurately.

6. 
   kostello | Jul 08, 2005 08:31pm | #10

   clever man.

   i hope the baby appreciates ot ;o)

7. 
   quicksilver | Jul 09, 2005 12:42am | #11

   Bravo, beautiful job.

8. 
   DonK | Jul 09, 2005 01:58am | #12

   Nice job David. I've done a little plaster work over the years. (My grandfather was in charge of the ornamental plasterwork at Ellis Island, and my Dad did it full time for years before sheetrock came out.)The wood/metal jig that you wound up with as a means of sanding down the plaster is similar to what most commercial plasterers would use on a running mold. One difference I would note is they usually use a piece of galvanized sheet metal for the cutter. It is probably harder than the copper. They also run that over the plaster when the plaster is still wet. It pushes the wet stuff along filling the voids. Your article mentions "wall plaster". There are different types of wall plaster. I think you meant the finish coat, which usually has slaked lime in it.  (Doing the lime and mixing it in proper proportion is part of the art; it also affects the finish of the final product.) If you can use the running mold and get the proper mix of plaster, you don't need drywall products. Keep sprinkling the finished piece with a little water and the mold will polish it so smooth a fly couldn't land on it. Rady to do the next one? Don

1. 
   user-53610 | Jul 09, 2005 02:18am | #13

   Wow!... great feedback! I'm mostly a weekend warrior when it comes to home projects (I write software for a living) so every unusual project starts with me wandering Home Depot in search of a potential solution (here is another example: http://www.kondra.com/booth/booth.html).Good advice about the sheet metal. I just happened to have some copper sitting around from making cookie cutters (long story) so I used that. As you can guess, the edge tended to curl over slightly over time so I'd periodically take it off and flatten it again (although I kept the copper overhang down to about 1/16in to try to avoid this).I think the real magic to this project is the correct choice of plaster. As you point out, the ideal case is to do everything in one or two coats while everything is wet. If I had to do another one of these I think it would go much faster now that I know a bit more about plaster materials.Thanks again for the feedback!

2. 
   msm | Jul 09, 2005 02:37am | #14

   cool lineage, hammerlaw! do you give workshops?
   what is a "running mold" exactly?david- i've been thinking of your dome all day, as i finish plastering an arched niche and figuring out framing for a closet in an excavated Fireplace... i wanna leave the whole mess and go make a dome.

1. 
   DonK | Aug 08, 2005 11:41pm | #23

   MSM - A while ago, you asked about a running mold. Never got any notification from BT, so I never responded. Happened across the old thread today.

   I don't give classes, because I don't know enough to do so. I like plaster, and respect those who do it well. I'm not overcome by the "artistes" that claim they are worth whatever they want to charge, because I've "been there". It's sloppy and messay, but it ain't gold leaf!

   On the question of a running mold, it is essentially a mold that is fashioned to be held against another guiding member while it is pushed along. For example, if one did a cieling cove, typically, there would be a piece of 3/4" wood level and down from the cieling, so that the bottom of the mold would rest on it as it was pushed sideways. That way everything stays straight.

   As far as your oval frame, that one is a bit beyond me. Actually, I had one for a bunch of years and got tired of looking at it.. Someday, I said. It didn't happen. If you cut the pattern for the plaster, you might be able to run it by hand, turning it as necessary. It would be worth a try.

   Good luck. Don 

9. 
   JerBear | Jul 09, 2005 05:15am | #15

   The beauty of your craftsmanship is only outshined by the determination within yourself to sit down and think on your own how to do such a project in a methodical way and then to execute it never doubting that it could be done. It shows imagination, creativity, and a whole lot of character. Very well done my friend, well done indeed.

1. 
   user-53610 | Jul 09, 2005 07:29am | #17

   Jer, Thanks for the kind words... I really appreciate it!You mentioned casting. Have you ever done any? I'd be interested to know how you provide strength for larger casts? For example, the dome I did was pretty simple in that I could shape it after putting the plaster over a frame. If you cast something like an ornate dome or a niche cap, how do you strengthen the piece? I was pretty worried about external forces cracking the dome once I had it mounted so I devised a mounting mechanism that put no load on the shell of the dome. But again, it only really worked that way because I could design the underlying frame that way... or am I underestimating the strength of plaster?

1. 
   JerBear | Jul 09, 2005 02:06pm | #18

   Yes, I have done field castings and I worked in a plaster casting shop in NYC for a while. Castings are reenforced exactly the way that you did. You created your piece by building onto a frame of wood and wire and then 'running' the finish on with a template. You built plaster around a frame. In casting you already have a mold that plaster is poured into. You create your mold by running a piece like you did, or you can carve clay, plaster or wood...whatever. In restoration, you make your mold around existing detail. You then make a 'negative mold' around that piece, and it is out of that negative mold you do your castings.
   As you pour you add the reenforcement to the wet plaster in the mold so it floats inside the plaster. We would use sheets of fiber synthetic or sometimes fiberglass mesh in several layers with casting plaster. Burlap was traditionaly used for this and still is used today. Burlap is good because it conforms well. I have seen wire mesh thrown into a casting as well.
   We would start the first pour by brushing a slurry of plaster into the fine detail work so there were no voids. Next some plaster was slowly poured to maybe a quarter inch or so deep. The fiber mesh was laid in then and we would have a bucket of plaster ready which was the consistancy of a milkshake which we would thickly brush onto the fiber cloth. You keep doing this until the mold has several layers and is finally built up to the level where you want it. There are different types of plaster specifically for casting which are much stronger and finer than plaster of paris so the detail can be very crisp. Plaster of paris is fine though and is very strong especially when reenforced. There are different steps that I have skipped over, like how to release a mold, what a 'mother mold' is, or the different steps to take with specific materials, but hopefully this gives you a brief overview of casting. The advantage to casting is that you can make several pieces out of one mold. When you run a piece, there's only one.

1. 
   msm | Jul 09, 2005 07:06pm | #19

   i'm curious- do we know for sure how well the plaster will stay attached to the foam base over a span of time? since this is a relatively new product/method... and when burlap is embedded in the plaster, should the burlap be soaked in water first, then wrung out? i'm doing a little plaster work myself, right now, making a decorative nich with arched top using a combo of drywall patched with plaster in an old existing wall of plaster and lathe, using 'plaster of paris'. i have always had the impression that you need to moisten areas recieving the plaster so they won't suck out the moisture from the new plaster too fast and cause cracking and a bad bond-and has anyone heard of mixing white glue into plaster or joint compound? it's supposed to lessen the brittle ness i believe-and yeah, i figured out the term "running mold'. i have long wanted to duplicate some old picture frames i have, in the 'tombstone' shape (arched top). they are oo damaged to make a mold from (plaster over wood but the plaster is chipped off in places), and i've been trying to figure out how to get the molding so perfectly uniform. now i know- a running mold! but i suppose you'd have to get an inside and outside track just right to go around the corners the same way each time; more difficult than the perfect circle.
   someday maybe i'll give that a try-
   thaks for all the inspirationthis is such a cool thread!

   Edited 7/9/2005 12:40 pm ET by MSM

1. 
   user-53610 | Jul 09, 2005 08:22pm | #20

   I had the same concerns about the plaster sticking to the foam long term when I got started. However as you sand the foam down the surface becomes very porous so I figured the plaster had plenty to bond to. In addition, since I applied the plaster by hand I was able to make sure it was worked into the foam surface.I kept going back and forth on what I though would be the most delicate apsect of the dome and tried to work around it. My two main concerns were:- Cracking : I was worried that the dome would get some lateral forces on it as things shift and settle (I'm in California so things shake from time to time). I tried to minimize this by mounting from the frame only.- Dropping : If the bond to the foam isn't secure in the long run, could the plaster fall out of the frame? I added a lip to the dome and it is held by the trim. I added wood backing to the ceiling so the trim is actually nailed into something solid. This goes against the first item as there is now pressure on the dome from the lip, but I figured it was better to be safe (that, and I moved the baby crib to the side of the room).That's the other thing I liked about the Hilti foam vs. Great Stuff foam. The Hilti foam cured very rigid which left me thinking there wouldn't be problems with shrinkage over time.Jer, Thanks for all the great info about casting! I really enjoy these unusual types of projects. A couple years back I built a block retaining wall in my back yard and wanted to top it with something other than just flat caps. I couldn't find anything so I built a mold and cast all my own caps (which took a while since I could only make 5 at a time, and only one corner or end per day). In the end I had something very distinctive and it wasn't that much work. Now if only I had the artistic ability to design a nice looking mold...

   Edited 7/9/2005 1:27 pm ET by David

2. 
   JerBear | Jul 12, 2005 06:42am | #22

   All your wood backing and framing to reenforce the plaster is exactly what you should be doing. If you're worried about cracking, you can always add fibers to the mix. They sell it in a good mason supply house.

3. 
   JerBear | Jul 12, 2005 06:25am | #21

   If the foam was real porous, the plaster should stay on fine. You should always scarify or deeply scratch the base onto which you apply plaster so that it has tooth. In your case, it depends on how porus the foam was, and how thick was the coat of plaster applied.
   Yes, mixing white glue into a plaster mix is an old way to strengthen the plaster. It's basically what the white bonder 'milk' is in plastering and stucco work, a binder.
   You should always dampen, not overly soak , anything that is going to get plaster applied to it. The plaster has to have some sucking action to pull it into the base material, and if the base is saturated with water it won't bond well. But yes, you don't want the base to be too dry as to suck out all the water from the wet plaster. In flatwork we spatter the scratch and brown coats with plaster brushes filled with water.
   Burlap is such a course weave that it takes in not only the water, but the tiny particles of plaster as well, the suspension. Have you ever had a cast put on a broken bone or seen it done? That's nothing more than a heavy gauze with dry plaster pressed into it. The Dr. then soaks the rolled up gauze and slowly wraps it around the broken limb.

10. 
    JerBear | Jul 09, 2005 05:23am | #16

    I did ornamental plastering for a while on top of my years of flatwork, lots of statehouses, churches and theaters. You are on the right track when it comes to how they would run a dome. It's done while the plaster is still wet and yes, with sheet metal template knives. Plaster moulding is either done by running it or casting. Great job!

11. 
    robteed | Aug 09, 2005 05:15am | #24

    Hey David,
    Good Job. Heres a link to my Domed Ceiling.
    http://forums.taunton.com/tp-breaktime/messages?msg=48128.31
    I built it out of a satilite dish that I picked up for free.
    Of course its a bit bigger then yours, Someone did give me
    a 5' dish after they saw my dome room. Told me to put more
    domes in other rooms to tie it all together.
    We have been building our house for the last 2 years.
    Its almost done. We are doing EVERYTHING ourselves...man what a job.
    Rob Teed
    Dream Builders
    Bath,Mi

1. 
   robteed | Aug 09, 2005 05:17am | #25

   Also, check out my plaster jig. Almost the same setup as yours.
   Rob

1. 
   user-53610 | Aug 09, 2005 07:03am | #26

   Great job!... I can only imagine how long it took to get everything coated for something that size. I also had an advantage in that gravity was working in my favor ;)