Plaster basecoat bubbled off of blueboard. What now? :Z

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houseofcakes

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Hi there,
I have a Plaster Disaster! Hoping the collective professional wisdom of this forum can help me out. I've done the USG blue board system in my house in several areas (somewhat competently) and not had any problems. This is the first time this has happened to me and I'm kind of at a loss as to what to do next.

I put up a wall and installed new board and put Diamond basecoat first to bring it up to level with the existing wall. When I came back a week later (we were on vacation), I noticed the lower half had a huge bubble and so I peeled it off. All the basecoat came off! It did not stick! The board is new (grey side facing), the basecoat is not. It's an old 1/2 bag I found. I did the top half with a new bag and that seems fine (on older board). Sooo, my questions are:

Does basecoat have a shelf life? Is that why it did not stick or should I suspect the board?
I have a bag of Diamond veneer plaster that is old. Should I toss it and buy all new bags?
(Both bags have been sitting in my basement for a couple of years which is not a super dry space, but not wet)
What should I do now that the board has had plaster on it in order to get new basecoat to stick to the board? Can I just spray it down with water and put new stuff on?

Ugh. :/

Thanks,
Karen
 
Thanks :) I wish I had found this forum earlier. But I don't think anything was around in 2005 when I decided that plastering was something I should do (which I am an idiot for thinking). But so far, I have been "okay." Flat paint helps haha.
 
houseofcakes said:
Thanks :) I wish I had found this forum earlier. But I don't think anything was around in 2005 when I decided that plastering was something I should do (which I am an idiot for thinking). But so far, I have been "okay." Flat paint helps haha.
Click to expand...

We do have a few American plasterers on here that maybe more familiar with the products you are using , I think @Loren is one, I forget the names of some of the others. @Curry may be able to help. best of luck :RpS_thumbsup:
 
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LOL, no sorry. I only make cakes for friends and my kid.

I also realized that I was supposed to intro myself. We bought a house in 2005 that needed almost every ceiling dropped out. I decided plastering was "cool" and so I did some research on modern day plastering and use USG blue board and Diamond basecoat and veneer coat. I sort of learned by trial and error and I think probably a lot of plaster ended up on the floor (and on me) instead of the ceiling/wall. I do have a cool 400 page plastering trade book from the 50s that is insightful (but ultimately not that helpful). I only make cakes for family, and I am a graphic designer with carpentry and other random skills. My greatest feat: I was able to replicate a curved ceiling corner detail in a room where we replaced the whole ceiling. All my plaster has held up in 9 years...until TODAY.
 
Ahh, I didn't realize this wasn't a US-based site. Derr.
 
@houseofcakes :)

Welcome :)

We have a few on here that can help you out @Loren is one and there are a couple of more I iwll do some digging and see who else can help :)

Welcome along :D
 
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Welp, I did the obvious thing. I called US Gypsum directly. They have a technical number! I didn't think they would answer random questions but the guy was super helpful. Here are the answers:

1. Basecoat/Veneer plaster bags--they say it's really only good for 6 months. (So into the trash goes the 2 bags of veneer I have as they are like 2 years old).
2. Blue board that's been already "used." Treat as if it's reg board and coat with bonding agent before reapplying plaster. I guess the board has a glue agent in it that makes the base "stick."

Voila.

I'm happy to have answers at least and have this forum for research and answers! :)

K
 
Hi House of Cakes, Yes there definitely is an expiration on basecoat veneer. I'm surprised that it wasn't a hardened lump when you used it. My first thought was that you might have had an area that had some residual dust on it, or an oily spot, did you spray any WD40 near the board? The only time that I've seen base coat not want to bond to a surface that it's supposed to go over was when I got called to do a lot of repair work at a new high school they were building. There were a lot of concrete walls that another plastering outfit had installed veneer plaster on and they had the same thing happen, it was popping off in different areas. We determined that it was the form boards they used, somebody had sprayed them with diesel oil and the concrete soaked some of it up and kept the plaster from bonding. I ended up painting those areas with Kilz (stain blocking primer) letting that dry and then painting on Larsons bonding agent over that before patching in the plaster. On the blue board, hopefully you did have the "Blue"side out, it's not a glue agent it has micro fibers embedded it the paper, if you look real close at the board you'll see them they also have a gypsum wash in the fibers that jump starts the veneer plaster to start setting after being applied to the board. Patching veneer plaster is not easy, hopefully you are doing smooth coat and not a sand finish. If it's smooth coat you can always skim the edges with joint compound and sand smooth.
 
Oh I forgot I saw a bunch of veneer plaster popping off on another job also, years earlier they were recommending that you prefill the joints in the veneer board with paper tape and taping compound, let it dry and then plaster over. Well years later we were doing a ninety room addition in this building and when you tapped on the wall you could hear hollow spots on most of those joints in the existing walls and in places it was falling off.
 
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