# Will joint compound stick to Zinsser 1-2-3?



## stadry (Jun 20, 2009)

it has at our house however we have wood crown molding, not plaster, so i've only done that on the orange-peel ceilings.


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## Just Bill (Dec 21, 2008)

I am not a plaster expert, but if the cove is completly gone, I think you will need some wire lath or similar for the mix to grab onto. I think plaster would be the better material, but either still needs more than paint as a backer. Build it up in layers.


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## Gary in WA (Mar 11, 2009)

I suggest priming or a bonding agent as you have, but not lightweight compound. Not enough adhesive as regular mud. Work your way around this site: http://www.plaster-wall-ceiling-solutions.com/old-plaster-questions.html
Be safe, Gary


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## user1007 (Sep 23, 2009)

I have done a lot of this in old houses and your approach with the shaping tool sounds good. If you need something more rigid cut yourself a piece of masonite or something. 

Plaster or compound will stick to the primer but that is not your biggest problem. 

Lightweight joint compound is not for this. And, you don't want to mix plaster and joint compound together. The chemistry is different. Either plaster or regular compound would be a better choice but as you probably know, the pre-mixed mud takes forever to cure if applied in any thickness at all. It is a bit of a pain and inconvenience, and you will have to work a little faster, but buy and mix dry compound (available cure times of 5-90 or so minutes) to control the consistency and curing time that works for you.

You can reduce the amount of compound or plaster you need by nailing in some simple triangular, etc. trim along the ceiling if you still have right angles there. I have never used wire or mesh for a radius as small as you are taking on.


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## Lovegasoline (Sep 11, 2009)

Thanks for the great ideas.

The cove curve is for the most part established, but it is choppy and roughly done. 

I was just reading elsewhere about the 'hot mud' or powdered joint compound with various drying times. That's a great idea and yes, as you mention, the slow dry time of regular joint compound is a HUGE drawback. I'm looking for a compound that I can sort of 'sculpt', work back into it a bit if need be, without lifting all the compound from the previous pass. Do the different set times of hot mud pretty much handle the same? 

What about a 'bonding agent'? Do I need to paint anything over the Zinsser primer to get the hot mud to stick? Do I also need to score the current surface to aid in a mechanical bond?

Re: plaster + joint compound:
The building owner skim coated a room/ceiling here and they used regular joint compound and mixed in about 1/4 plaster...so I was thinking this was a good mixture. I've tried it on some other small wall areas and it dries faster than the joint compound. I hope that room doesn't run into problems downt he road due to the mixture.

Thanks again, great ideas.


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## bjbatlanta (Jul 16, 2008)

Yes you can go right over the Zinser. I use it or Kilz to kill water stains and mud over it all the time. If the curve is already there and all you're looking to do is "skim" the shape back, no need for wire mesh. Try to scrape/grind down any high spot as best you can. If there are any small cracks, you could use some fiberglass/mesh tape then mud over. I don't like or use "lightweight" for anything and would definitely not use it for your situation. A setting type compound (45 or 90 minute might be best) is definitely what I would use. A final skim with regular ready mix will help fill in any small "craters". And there are finishing "knives" made of rubber that will conform to a rounded corner. A tool supplier that carries drywall tools will have them. All-Wall.com and ToolSourceWarehouse.com are a couple that come to mind....


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## user1007 (Sep 23, 2009)

You'll be able to work the dry mixed compound until it starts to set up and you should have no problem between layers. Note that the drying times on the boxes/bags are approximate. Unless you can move fast and/or have someone to work with you to mix the compound the 5 minute version will probably not leave you enough time to work the shape you need. Also remember that it starts to cure as soon as you add water so you might want to use a drill and paddle to speed the mixing process. 

You might add something like No Pox to aid with cleaning tools and for a nice smooth surface but this is an option.


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## Lovegasoline (Sep 11, 2009)

Yeah since I'm an amateur, I'll probably need the longer cure time of the 60 or 90 minute cure hot mud and/or work in segments. 

The rubber corner tool (looks like they call it a 'bat'), if it would work sounds like_ just_ what I would need.
Here's one:


http://www.all-wall.com/acatalog/Rubber_Corner_Tool__Bat_Knife__.php#aCPT


...unfortunately, they do not state the radius of the curve. Do you know if the rubber on this tool will conform to a 1.5" - 2" radius cove? I measured the plastic squeegee tool I made and the radius is a bit smaller than I had first thought. 
The right tool combined with the hot mud I imagine would _really_ speed this job along. And I am now seeing I have about 130 linear feet of this cove smoothing/restoration work to do (I'm gonna hit the entrance hallway & foyer in addition to the dining room) and I really will need to knock this out in a couple days.

The foyer and hallway do not have the Zinsser primer, just what looks like eggshell or satin latex paint at least 8+ years old. Is there a need for a binding agent over the paint before applying the hot mud? 

Thanks again for the great ideas!


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## user1007 (Sep 23, 2009)

I cannot tell the radius of the tool but judging from the dimension of the handle, it looks bigger than 1.5-2"r so you will probably have to make yourself something. Or, your original idea of finding a rigid plastic lid might work. Put the compound on with a putty or drywall knife and then shape it. Once you find the right tool and get the thickness of the mix where you want it this should go fairly fast especially now that you realize the smaller radius. 

As long as the paint is not too glossy or peeling and the surface is clean you should be alright without a bonding primer. If you have extra and want to wait for it to dry it would not hurt though.


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## Lovegasoline (Sep 11, 2009)

I had tried applying the compound (regular pre-mixed) to the wall with a knife first, then shaping it but it was unworkable. It pulled off the wall or left large gaps and chunks.

I found a method whereby I loaded a large fist size amount of compound to my ‘squeegee’, making certain to even out the amount of compound across the tool’s surface and clean it of any excess, then I pulled that along the cove and it would release a trail of compound nice and smooth. But it was slow going and very precise work, often redoing the same area a few times to get a smooth and consistent release from the tool.

Maybe with hot mud and at a thicker consistency, the material will be more ‘plastic’ and can be more easily shaped, while still releasing smoothly from the tool.


What is no-pox?


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## paddy 43 (Sep 27, 2009)

When you are making good of anything you should allways use a bonding agent so the compound or plaster holds properly and allso gives it retarder giving you time to work with.


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## bjbatlanta (Jul 16, 2008)

If you are talking about "plaster" in the true sense of the word, you may be correct. As far as "setting type" joint compound, there is no "bonding agent" needed when going over plaster....


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## Lovegasoline (Sep 11, 2009)

It sounds like good insurance to use the bonding agent (unless it introduces problems of its own?). What products are recommended? Are they available at big box stores or do I need to go to someplace more specialized...and are they relatively inexpensive? 


Thanks again guys, you've been a great help. I'm going to start the job today or tomorrow.


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