# Veneer Plaster over Joint Compound Patch?



## Tonyg (Dec 9, 2007)

I have always been able to patch just about any repair and have been pretty good about blending textures. I've done some plastering but limited to partial walls and patches.

Down here we have all sand finished walls and usually I can use joint compound to match the texture pattern. I have recently started doing the board replacement and base coat on larger holes (10"x12") with joint compound and then finish off with a coat of veneer - seems to look better.

My concern, that I have not been able to find an answer on, is will there be any delamination problems later? Will the veneer plaster bond to the clean joint compound? 

Any plasterers on here?


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## daArch (Mar 15, 2008)

I'm a wannabe plasterer, and I apologize for offering my opinion even without a master plaster's knowledge or experience.

The chemistry of plasters is voodoo. Even when I've put new veneer over old scratch coat, it needs a bonding agent (I like Weld-o-Bond - there are many others)

Are you using setting JC (hot mud) or evaporative JC (pre-mix) ?

As you know, blue board is used under veneer - for adhesion reasons. 

Without knowing the answer as to how JC and veneer will react to each other, I would:

A) research

B) apply a bonding agent

We all know that JC can adhere to veneer because JC has a lot of glue in it. But the other way around ? 

Personally, I would hesitate about putting Veneer plaster over evaporative JC. But that comes from fear, not knowledge.


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## Tonyg (Dec 9, 2007)

I usually keep the Blue Diamond veneer and both the durabond and the premixed JC. Been using the ready mixed the last couple of patches and then finished with the veneer. I think the ready mix would not have a chem reaction that would prevent bonding.

I read something on JLC where they compared the blue board and regualr sheetrock and delamination wasn't a problem, although it did dry slower causing some problems with 2nd coat. The blue board draws the moisture in helping dry time and bonding. 

Kinda hate going to the plasterers board - kinda like one of them coming here asking how to paint for their customer


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## daArch (Mar 15, 2008)

I just read that too Tony, looking for answers to your question.


And as you have discovered, tough to find an answer to your particular question.

Maybe best to wait til Monday and call USG. Or find an old school master and ask.


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## Tonyg (Dec 9, 2007)

I've used plaster weld as a bonding agent when patching around old base coat or on sections that I though may have bonding issues. It's just an extra step and dry times where I would just end up using joint compound instead.

There is a supplier nearby that specializes in plastering so I'll make a stop this week to talk with them


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## daArch (Mar 15, 2008)

Let me know what they say :thumbsup:


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## mikeyj36 (Oct 27, 2014)

I'm a plasterer 20 years, you can apply veneer plaster directly over setting type compound, national gypsum recommends pretreating seams with setting type compound and paper tape to avoid cracking, the only time I would apply a bonding agent is when going over existing painted surfaces, also Quickcrete bonding works as good as the more expensive bonding agents, do not apply plaster directly over reg JC, it will re wet and cause delaminating


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## RESTORED (11 mo ago)

[Q


mikeyj36 said:


> I'm a plasterer 20 years, you can apply veneer plaster directly over setting type compound, national gypsum recommends pretreating seams with setting type compound and paper tape to avoid cracking, the only time I would apply a bonding agent is when going over existing painted surfaces, also Quickcrete bonding works as good as the more expensive bonding agents, do not apply plaster directly over reg JC, it will re wet and cause delaminating


UOTE="mikeyj36, post: 523344, member: 23313"]
I'm a plasterer 20 years, you can apply veneer plaster directly over setting type compound, national gypsum recommends pretreating seams with setting type compound and paper tape to avoid cracking, the only time I would apply a bonding agent is when going over existing painted surfaces, also Quickcrete bonding works as good as the more expensive bonding agents, do not apply plaster directly over reg JC, it will re wet and cause delaminating
[/QUOTE]


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## RESTORED (11 mo ago)

Damon, excuse me, I have been researching numerous issues or for my own knowledge info about plastering. First, only JC, durabond, and veneer plaster are the products anyone can put their hands on, the time it takes to get to a big box store. Base coat plaster, is impossible to get unless you order on line and with the supply chain issues, maybe get in 3 weeks. I have even called USG, and can't get straight answers about using different methods for different issues. Your comment is reflective of so many about plastering. Maybe I'm just not reading correctly, but I interpret your comment as yes you can and no you can't. These answers are so typical. Second the various tapes and products I'm getting a strong feeling that they are called different things in different parts of the country. Setting type compound??? All compound sets up. I have to assume your referring to durabond product. ??? You begin by saying You can apply veneer plaster over setting type compound. hen you say it can't be applied over JC. If I recall the that was the question. The compounds have different chemicals in them, but even regular JC can be bought in a bag and mixed yourself. What is prep your seams???? You say use a paper tape. However not to use a bonding agent. What else would one do the treat the seams. I have found so many answers to questions about this trade, left to numerous assumptions for each question and leave the thread, with NO answer. The same result I had calling USG directly. Though the guy who is suppose to know was off on Presidents day., lol. Referring to their PDF files is like, forget it. There is more discussion about laterals and horizontials of which I'm assuming again it's a part of the hanging process and has absolutely nothing to do with the basic question. Can veneer plaster be applied over JC. The answers are typical when the question is will it bond to regular drywall. I can find more info about people putting plaster over regular plywood and exposed to the elements than a straight answer to JC. It is frustrating, because it is the same question I asked. I have JC on old plaster that is clean and has a bonding agent, and has parts that are skim coated with JC. More old plaster to bond to but my guess is 35% of a stairway has been patched, taped, finished with JC. I want to skim it all with veneer plaster. I'm sorry but don't trust your answer, as I think there are 2 answers. And they are totally opposite. Sorry for showing my frustrations. I can put my hands on Veneer plaster. I can get base coat veneer plaster also. So all repair work needs a basecoat, Red Top I believe is what USG told me. Half the big box stores don't even have a decent supply of blue board. I read a post a couple days ago and someone asked if they could plaster over 3/8" drywall. The answer went on about not enough strength. Use at least 1/2". That wasn't the question, it was stated for the purpose of getting the right bond and being sheetrock because they didn't want to remove all the lath. I also had the same question why I found that question posted. If the house is older the plaster butts ALLL the trim. So the pro who answered, didn't take into acct. it would end up costing 20 times plus to increase the thickness of the wall board. 3/8" over 3/8" wood lath. That time period, studs were put up on the flat. most all 4" wide. 3/8" drywall on the wood lath is more than sufficient to hand new drywall on. Otherwise the finish wwall would be even with or protrude beyond all the trim. The question was to do with will the plaster bond to the 3/8 " drywall. Period. The asker even touched on the wall thickness he had to achieve and why his only option was 3/8's drywall. He didn't mention the interior trim, but doing this since the mid 1960's it was very easy to see what the issues were. And I just happen to be dealing with the same thing right now. My house was built in the 1780's. Big box stores and lumber yards if they are going carry veneer plaster, then they need to have at least 4-5 bags of basecoat on hand. The makers and suppliers of the products need to have answers to a half dozen basic questions. From spending about 16 hours online searching for info about plastering, the basic questions are all the same. What will the products bond to. Bonding agent. Type in and ask how to make your own. What a nightmare to get a straight answer. It's all made with elementary school white glue. Why pay 60 a gallon? USG even told me if I didn't have the right base coat, to wait but with any questions at all about bonding, as there can be dozens of reasons to question this, to add white glue when I mix the plaster. at a 2=1 ratio, but I didn't hear it from them. I realize bonding and cracking is test of time. But I believe I was way over thinking the entire process. I'm inclined to believe the same with over JC or over durabond. Mny of the properties are the same. the dura if this is what you were referring to,. is closer to plaster in its hardness, set time, sanding issues. I am however still unsure about skimming my project with a straight veneer plaster. of which doesn't have the sand or aggregate that the base coat has. JC bonds to old plaster. VERY WELL. Even to painted areas of latex. Oil paint no. The JC will loosen wall paper, My guess is not knowing the properties maintaining the mosture pentrates the left behind wall paper and makes it easy to remove. I have used it to remove old wall paer that the walls weren't sized and the paper loaded with glue. Still sitting on top of the old basenoard is a giveaway. There has to be a more direct, answer to the question. Two answers for the same question doesn't help. treating the seams ???? If using the special compound don't mix much if taping with paper. Also the fiber mesh, has gotten cheaper, not nearly the same amount of adhesion as 1- to 15 years ago.


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## Susan (Nov 29, 2011)

RESTORED said:


> Damon, excuse me, I have been researching numerous issues or for my own knowledge info about plastering. First, only JC, durabond, and veneer plaster are the products anyone can put their hands on, the time it takes to get to a big box store. Base coat plaster, is impossible to get unless you order on line and with the supply chain issues, maybe get in 3 weeks. I have even called USG, and can't get straight answers about using different methods for different issues. Your comment is reflective of so many about plastering. Maybe I'm just not reading correctly, but I interpret your comment as yes you can and no you can't. These answers are so typical. Second the various tapes and products I'm getting a strong feeling that they are called different things in different parts of the country. Setting type compound??? All compound sets up. I have to assume your referring to durabond product. ??? You begin by saying You can apply veneer plaster over setting type compound. hen you say it can't be applied over JC. If I recall the that was the question. The compounds have different chemicals in them, but even regular JC can be bought in a bag and mixed yourself. What is prep your seams???? You say use a paper tape. However not to use a bonding agent. What else would one do the treat the seams. I have found so many answers to questions about this trade, left to numerous assumptions for each question and leave the thread, with NO answer. The same result I had calling USG directly. Though the guy who is suppose to know was off on Presidents day., lol. Referring to their PDF files is like, forget it. There is more discussion about laterals and horizontials of which I'm assuming again it's a part of the hanging process and has absolutely nothing to do with the basic question. Can veneer plaster be applied over JC. The answers are typical when the question is will it bond to regular drywall. I can find more info about people putting plaster over regular plywood and exposed to the elements than a straight answer to JC. It is frustrating, because it is the same question I asked. I have JC on old plaster that is clean and has a bonding agent, and has parts that are skim coated with JC. More old plaster to bond to but my guess is 35% of a stairway has been patched, taped, finished with JC. I want to skim it all with veneer plaster. I'm sorry but don't trust your answer, as I think there are 2 answers. And they are totally opposite. Sorry for showing my frustrations. I can put my hands on Veneer plaster. I can get base coat veneer plaster also. So all repair work needs a basecoat, Red Top I believe is what USG told me. Half the big box stores don't even have a decent supply of blue board. I read a post a couple days ago and someone asked if they could plaster over 3/8" drywall. The answer went on about not enough strength. Use at least 1/2". That wasn't the question, it was stated for the purpose of getting the right bond and being sheetrock because they didn't want to remove all the lath. I also had the same question why I found that question posted. If the house is older the plaster butts ALLL the trim. So the pro who answered, didn't take into acct. it would end up costing 20 times plus to increase the thickness of the wall board. 3/8" over 3/8" wood lath. That time period, studs were put up on the flat. most all 4" wide. 3/8" drywall on the wood lath is more than sufficient to hand new drywall on. Otherwise the finish wwall would be even with or protrude beyond all the trim. The question was to do with will the plaster bond to the 3/8 " drywall. Period. The asker even touched on the wall thickness he had to achieve and why his only option was 3/8's drywall. He didn't mention the interior trim, but doing this since the mid 1960's it was very easy to see what the issues were. And I just happen to be dealing with the same thing right now. My house was built in the 1780's. Big box stores and lumber yards if they are going carry veneer plaster, then they need to have at least 4-5 bags of basecoat on hand. The makers and suppliers of the products need to have answers to a half dozen basic questions. From spending about 16 hours online searching for info about plastering, the basic questions are all the same. What will the products bond to. Bonding agent. Type in and ask how to make your own. What a nightmare to get a straight answer. It's all made with elementary school white glue. Why pay 60 a gallon? USG even told me if I didn't have the right base coat, to wait but with any questions at all about bonding, as there can be dozens of reasons to question this, to add white glue when I mix the plaster. at a 2=1 ratio, but I didn't hear it from them. I realize bonding and cracking is test of time. But I believe I was way over thinking the entire process. I'm inclined to believe the same with over JC or over durabond. Mny of the properties are the same. the dura if this is what you were referring to,. is closer to plaster in its hardness, set time, sanding issues. I am however still unsure about skimming my project with a straight veneer plaster. of which doesn't have the sand or aggregate that the base coat has. JC bonds to old plaster. VERY WELL. Even to painted areas of latex. Oil paint no. The JC will loosen wall paper, My guess is not knowing the properties maintaining the mosture pentrates the left behind wall paper and makes it easy to remove. I have used it to remove old wall paer that the walls weren't sized and the paper loaded with glue. Still sitting on top of the old basenoard is a giveaway. There has to be a more direct, answer to the question. Two answers for the same question doesn't help. treating the seams ???? If using the special compound don't mix much if taping with paper. Also the fiber mesh, has gotten cheaper, not nearly the same amount of adhesion as 1- to 15 years ago.


Okay.
Thank you


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## celicaxx (May 29, 2015)

I had a hard time reading through that all with no paragraph breaks, so next time you revive a 8 year old thread it might be better to at least use paragraphs. But since I love plaster and talking about plaster, I'll do my best.

For a short and long, go on Youtube and look up Kirk Giordano plastering, he's not perfect but he's as close as you can get to that, and an amazing plaster teacher. I learned a lot from him.

For your other questions, for a basecoat in my bathroom I did with plaster I simply used Structolite, which at least where I live every Home Depot seems to carry. The only difference with a Diamond, Red Top, or Imperial basecoat is the sand is silica sand. Structolite being LITE uses perlite as the aggregate, which is what gives you strength and gives the veneer coat something to adhere to. I think maybe the Diamond base coats might have a thinner aggregate, but Structolite is plenty fine as a basecoat. Veneer plaster does NOT need a basecoat actually, but it's recommended, there are single coat and double coat veneer systems over drywall/blueboard where you tape the seams with Durabond, then skim coat the whole wall with veneer plaster.

For bonding agents, simply go to Home Depot and buy Quikrete Concrete bonding agent, it's warrantied for plasters. I believe it's more or less a PVA glue which means wood glue/Elmer's Glue, but it might have some special something. It's cheap, $15-20 a gallon (used to be $10 a few years ago .) Just roll it on like paint, and go plaster, seems dry time doesn't matter with it. If you want something better/more high end, call a masonry supply yard or special order from a real paint store (ie, Benjamin Moore dealers) Larsen's Plaster Weld or Weld Crete. All I've ever used is the Quikrete and it's fine and does what it needs to do.

For your specific job, you're sort of vastly overcomplicating things. I would pretty simply just coat everything with the Quikrete bonding agent then probably use whatever USG Easysand or similar setting joint compound (by setting we mean chemical set, not just drying like premix does) and skimcoat over it. I probably wouldn't use a veneer plaster as while it will in fact work, veneer plaster is not sandable and likely you're not skilled enough to get a flat wall troweled down without sanding. Easysand allows you some sanding, but it doesn't sand as well as premix drying compound does due to being harder due to being basically a hybrid plaster. Durabond would also work, but Durabond sands worse than Easysand, thus why Easysand is called Easysand. The only upside a veneer plaster gives you is the touch/feel/durability, veneer plaster walls feel cold to the touch and it's more dent/scratch resistant than joint compound, and veneer plaster has more "fat" and trowels out better. The other downside of using a veneer plaster is you need to wait 28 days for it to cure before painting it, and/or know what primers and paint combinations adhere well, whereas using normal Easysand any paint/primer combo will work fine. 

For a basecoat, really you only need a basecoat if you're redoing the plaster down to the keys in the wall, or if you're in general doing a deep/wide/big repair. The problem with a veneer plaster or even setting joint compounds is while you can go thicker, they don't tolerate being applied over ideally about 1/8" at a time, with a max of about 1/4" before they start blistering or basically falling off the wall. So if you have a deep repair, or even if you're going over sheetrock and you want to say, make everything flat and you have one ceiling where there's 1/4" of texture on top of everything and the next section is bare sheetrock, just using Structolite basecoat would be the easiest way to skim it all flat, then you can topcoat with veneer plaster or a setting joint compound.

For using a bonding agent too, the other purpose is to kill suction, not just provide glue for the material. Before bonding agents existed if you had wooden lath people would just wet the lath with water, and on masonry walls people would just wet the wall a lot, as otherwise the material dries as you're putting it on, and dries before it sets (the difference between setting and drying compounds again) and thus it never develops full hardness as it can't chemically cure properly. So on a given surface using one vs not, that's another thing to consider, a bonding agent gives more working time but the main purpose isn't just to glue it to the wall, but to make sure the material can fully set without drying out.

Anyway, it's not a field you can instantly learn, and you seem to be a DIY and this is a forum for pro paint contractors so you may not be allowed to post here, but it's information for people to find out about how plaster works and answer some basic questions. Still, Kirk is the best.





Check out this video of him using Structolite over a cement board fireplace and truing/leveling up stuff, too.


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## Redux (Oct 27, 2018)

celicaxx said:


> I had a hard time reading through that all with no paragraph breaks, so next time you revive a 8 year old thread it might be better to at least use paragraphs. But since I love plaster and talking about plaster, I'll do my best.
> 
> For a short and long, go on Youtube and look up Kirk Giordano plastering, he's not perfect but he's as close as you can get to that, and an amazing plaster teacher. I learned a lot from him.
> 
> ...


A couple of advantages of PlasterWeld over Quikrete Concrete Bonding Adhesive is that PlasterWeld contains a silane coupling agent/adhesion promoter (Octamethylcyclotetrasiloxane aka D4) which provides a more tenacious bond, and also increases the substrate’s hydrophobicity, further reducing suction. 

Also, gypsum veneer plaster can typically receive final decoration within 48 hrs after applying…no reason to wait 28 days. 28 days is a general rule of thumb for lime plaster which requires uptake of atmospheric CO2 to carbonate/cure, yet the curing of lime plaster is more critical when priming w/fatty acid containing linseed oil paints/primers which can result in saponification of the fatty acids when applied to uncured alkaline lime plaster. Modern acrylics are more tolerant to high pH substrates.


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## Redux (Oct 27, 2018)

celicaxx said:


> I had a hard time reading through that all with no paragraph breaks, so next time you revive a 8 year old thread it might be better to at least use paragraphs. But since I love plaster and talking about plaster, I'll do my best.
> 
> For a short and long, go on Youtube and look up Kirk Giordano plastering, he's not perfect but he's as close as you can get to that, and an amazing plaster teacher. I learned a lot from him.
> 
> ...


I’d also like to mention the idea that lime plaster needs to cure before painting has become more of myth rather than fact with the advent of modern 100% acrylics. Even prior to acrylics, some modified alkyd resin primers (not to be confused w/alkyd emulsions) weren’t all that pH sensitive and could be used on hot masonry & uncured plaster without resulting in saponification, as long as the plaster was dry but not necessarily cured.


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## celicaxx (May 29, 2015)

Redux said:


> I’d also like to mention the idea that lime plaster needs to cure before painting has become more of myth rather than fact with the advent of modern 100% acrylics. Even prior to acrylics, some modified alkyd resin primers (not to be confused w/alkyd emulsions) weren’t all that pH sensitive and could be used on hot masonry & uncured plaster without resulting in saponification, as long as the plaster was dry but not necessarily cured.


Super interesting and I wish I knew that earlier. I waited the full 28 days for my veneer job in my own house. Zinsser on the phone asking about primers told me to wait the full 28 days. :/ 

In other people's houses I've done Structolite as a basecoat and then Easysand as the finish coat and painted in a couple days, and everything was fine. My figuring was since the Structolite was deeper than the Easysand my finish coat mattered more for adhesion. 

An idea I had in my own bathroom (it ended up being a disaster and I reskimmed it twice with joint compound) is perhaps the best plaster primer is probably Gardz? Gardz has also been amazingly moisture-proof of a primer as well in my use case. Reason being it's so thin and penetrates well, whereas normal primers would just sit on top of the plaster and have less ability to penetrate, especially with a burnished finish. I know in UK seemingly standard practice has been to thin their latex wall paint to milk consistency about 50% on their first coat so it penetrates into the plaster. I think the same would apply to normal joint compound skimcoats, too, where you'd want something thinner with better penetration vs something thicker, whereas a thicker primer would help possibly with bare drywall without a skimcoat as you're always dealing with fuzzed paper from sanding, etc, and paper is a different substrate anyway. So a thicker primer that can be knocked down a little and hides the sanding fuzz/scratches/etc would be preferable depending on how good your prep is (except some people rather like Gardz for bare drywall, too.)


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