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October 22, 2008
How To: Plastering Where Wall-meets-Ceiling Curved Radius?
I am skim coating (lightweight joint compound over plaster) for the first time. I’m using a 6” taping knife and things are working out OK. However, this is a pre-war building and there is a curved radius where the wall meets the ceiling, instead of a sharp right angle as seen in contemporary structures
. The radius is about 1-1.5”. Past chumps had made a little bit of a mess in this area. Instead of a smooth radius curve, it has ridges in areas where obviously the wrong tools/skillset/techniques were employed.
I am now facing the same challenge. How do I get a smooth transition from wall-to-ceiling , keeping the curved radius with the joint compound? Is there an inexpensive tool to use? The taping knife isn’t cutting it.
I need to do this on a super minimal budget because I do not own, I rent the space and I am doing the work out of my own pocket (to preempt the expected questions: I am rent regulated, lived here for decades, will likely live here decades more, great place, but landlord is out of the picture).
Thanks.
Comments
Cardboard paper towel roll.
Posted by: Pipecock at October 22, 2008 8:23 PM
Have you tried that?
Doesn't seem that it would last too long...I have to do an entire room 12' x 22'.
Posted by: Oxygen at October 22, 2008 9:06 PM
Are you talking about a cove ceiling? I'm pretty sure that traditional plasterers made their own molds or jigs for each cove. Maybe you can cut one from a plastic squeegee or PVC pipe? Also think that there have been previous Forum threads on this topic, as well as articles in the NY Times and video How-To's on either This Old House and/or Bob Vila.
Posted by: vinca at October 22, 2008 9:57 PM
Well,I tried a tube of caulk as a squeegee, but it didn't release the joint compound in a smooth manner. It seems the tool would need the sharp edge of a squeegee/sheetrock type of tool in order to release the JC smoothly.
Yes, I suppose you would call it a cove profile.
The project is stumped.
I really need to get this completed and get my room back from plaster dust limbo.
Well, back to the drawing board.
Posted by: Oxygen at October 22, 2008 10:15 PM
Oxygen --
For one thing you're using the wrong size blade. Move up to a 12", and you can buy excellent plastic 12" blades at Home Depot for like eighty nine cents.
For the curve, you need to use care that you would for a wall only more so. Throw out your buckets of premixed compound and by the bags of powder. Plan on doing three coats carefully -- you're not trying to do this in one pass.
For the second and third layer, add a slight bit more water to your mud, the third layer should be the thinnest.
The curve should be the last thing you tackle. By the time you build up the skills in the rest of the room, you'll be a ace.
Good luck!
Posted by: Smokychimp at October 22, 2008 10:56 PM
We have the same type of curved radius in many rooms of the house. Sorry to say, but I don't think keeping/restoring the radius, once disturbed, is a job for an amateur. Why don't you call in a skilled plasterer for just this aspect of your project? It may cost more than you intended to spend but could be worth it to you in the long run -- especially since you intend to stay there for the long run.
Posted by: Brooklynista at October 22, 2008 11:10 PM
As Smokychimp already said get rid of the "bucket mud" and switch to "hot mud". After the initial application you will need to water trowel the cove. Clean you knife with water and splash or spritz the cove with water to break the friction. If you do it correctly you will not need to sand.
Also, if you modify your knife so the edges don't touch it will make it a lot smoother.
There... I have exhausted my knowledge of plastering techniques(almost).
Posted by: southslope at October 22, 2008 11:14 PM
I'm still not getting a clear picture in my mind.
The coves are not devastated; I’m just trying to smooth the curves out.
The curves ARE the last thing. The room is ready to go except for the curves. The walls are sweet planes. There’s some rough 220 sheetrock screen marks which need sanding out, otherwise the walls like nice.
I’m using lightweight joint compound. I’ve been thinning in successive applications. I’m shooting for 3(+) applications.
What exactly is the benefit of mixing my own compound? What working properties does it have? What product is recommended?
I almost feel that either a slightly longer (not wider) blade and/or a more flexible blade would make turning the contour easier.
Because the inside radius of the cove (about 1”-1.5” radius) has already been grooved by poor paint/plaster work in the past, when I swing the semi-stiff spatula upwards it tends to ride along the grooves and repeat them instead of gliding over them and laying down a swath of compound. Perhaps the compound is an issue in the way it applies and allows me to work back into it (or not work back into it). It doesn’t feel very forgiving.
Thanks for all the ideas!
No way I could afford to pay someone to do this.
Posted by: Oxygen at October 22, 2008 11:42 PM
What do you mean by modifying the knife edges? You mean filing both sharp corners?
Posted by: Oxygen at October 23, 2008 12:24 AM
Not knowing much about plastering but here's my 2c: could you not get a plastic blade and snip it to the contour of the cove? As for the original stuff, I'd think you'd either have to sand or otherwise get rid of spots too lumpy for the contour anyway, no?
Posted by: cmu at October 23, 2008 8:50 AM
Our plaster actually used a snapple bottle to smooth out the curve (replicating a curve) in our bedroom. It sounds like your curve has a sharper radius, what about a Redbull can? They are smaller and likely would hold up better than a paper towel roll.
Sorry to not be more helpful,
Brooklyn.
Posted by: Brooklyn11218 at October 23, 2008 9:02 AM
Rubber spatula. Worked for me. The small kind. 1 - 1.5 inch
Posted by: Adam Dahill at October 23, 2008 11:44 AM
Thanks for all the ideas.
What sort of powdered compound should I be using instead of the lightweight joint compound?
Posted by: Oxygen at October 23, 2008 4:04 PM
It looks like I have a solution.
I cut a circular profile from the plastic lid of a joint compound bucket. I use it as like squeegee running it lengthwise along the cove leaving a thin coating of compound.
When dry, I will follow-up with a repeat coat, then after that, touch up any gaps.
One question in general about skim coats. I'm using premixed lightweight joint compound because it is easier to sand. After the 1st coat dried, I knocked down any lines and high points with the taping knife. Then, I went back in with a 220 drywall sanding screen tolevel out any areas that needed it. After 2nd coat and then a third touch up coat to fill pinholes, etc., for my final finish should I fine sand with sandpaper or should I strive to get the last coat applied smooth enough to not need to sand?
Thanks again.
Posted by: Oxygen at October 23, 2008 5:35 PM
It looks like I have a solution.
I cut a circular profile from the plastic lid of a joint compound bucket. I use it as like squeegee running it lengthwise along the cove leaving a thin coating of compound.
When dry, I will follow-up with a repeat coat, then after that, touch up any gaps.
One question in general about skim coats. I'm using premixed lightweight joint compound because it is easier to sand. After the 1st coat dried, I knocked down any lines and high points with the taping knife. Then, I went back in with a 220 drywall sanding screen to level out any areas that needed it. After 2nd coat and then a third touch up coat to fill pinholes and errors, for my final finish should I fine sand with sandpaper or should I strive to get the last coat applied smooth enough to not need to sand?
Thanks again.
Posted by: Oxygen at October 23, 2008 5:36 PM
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