# Acrylic/Latex Repaint Blisters



## spektrum (Mar 11, 2010)

I've had this issue numerous times and its so annoying and cannot figure out why it is happening. Someone please help. 

On many repaint jobs, I will pole sand entire surface with 120, repair with drydex or all purpose synko joint compound. Spot prime with pva primer and then 2 topcoats of acrylic/latex. Whatever brand is spec, dulux/bm/sw I've had the same issues, summer/winter.

Problem is, dreaded blisters after applying topcoats. Most of the times these are not areas I even patched, on either flat ceiling or eggshell walls. The blisters if you scrape go back to bare drywall. I do not get why after a home has sat with good ventilation for 10 or more years, there is moisture issues causing blisters...

I will let the coat dry, scrape sand, patch, spot prime with alcohol based spray bomb, let dry again sand to dull and put on final coat to whole surface. The problem will be less severe but it never goes away completely, and at this point I will leave it for a day or two and someone of the smaller blisters shrink back, but some are still present.

I know anyone who has painted has ran into this, but WHYYYYYYYY. Blisters are moisture issues. How does this happen when a house is bone dry. If the job is big enough I will not recoat same day in most situations but still these annoying blisters show their ugly face.


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## Damon T (Nov 22, 2008)

For realz? 
Doesn't ring a bell.


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## The 3rd Coat (Aug 17, 2013)

Not necessarily moisture. Most likely just poor adheasion of the previous coats. I did a weatherboard house exterior recently that had bubbling paint everywhere. Once I sugar soaped and pressure washed everthing, scraped back all the bubbles/blisters, primed and painted, new bubbles started forming, because of the added weight of the new paint film. I had told the client that the ideal solution is to strip the whole siding and start from scratch, but their budget didn't allow for that, so they're ok with the blisters here and there.

I suspect the same is happening in your case. Even if just one previous painter was a hack who didn't get the preparation right, bubbles/blisters will be a given with every paintjob afterwards.


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## Brian C (Oct 8, 2011)

wow, I think you should stay away from weatherboard houses mate. Your preparation is lacking. I strip off the old paint back to bare timber on most old houses because it will probably blister if you paint over it.


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## Damon T (Nov 22, 2008)

I believe the op was referring to interior work. I've seen plenty of blusters on exterior, but drywall is a different story. Something doesn't add up.


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## Workaholic (Apr 17, 2007)

Damon T said:


> I believe the op was referring to interior work. I've seen plenty of blusters on exterior, but drywall is a different story. Something doesn't add up.


I have seen blister bubbles on interior drywall repair. Sometimes it is caused from spakle, sometimes it is caused from buffing/polishing the mud repair rather than simply giving it a sand. A lot of variables. Need pics and more details to speculate further.


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## ridesarize (Jun 19, 2012)

I would guess that original drywall was dusty when primed or textured. Oh BTW you know moisture is introduced when you spackle or paint, the moisture sneaks under surface products and lets it loosen up. Maybe they used crap primer? Maybe house was not warm enough when it was primed originally.. maybe it wasn't primed? I've pretty much only had that problem when a NC home was very cold with no or little heat. And it only pulled bad where we taped on the walls. Other guess is too tight of home so moisture is not going out


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## The 3rd Coat (Aug 17, 2013)

Brian C said:


> wow, I think you should stay away from weatherboard houses mate. Your preparation is lacking. I strip off the old paint back to bare timber on most old houses because it will probably blister if you paint over it.


That was my original suggestion to the client but they didn't wanna pay for it. They're happy with blisters, I'm not going to argue with them.


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## The 3rd Coat (Aug 17, 2013)

ridesarize said:


> Maybe house was not warm enough when it was primed originally.. maybe it wasn't primed?


Nowadays it's common practice in my country to do 2 coats of ceiling paint on ceilings without primer.
That's why I have no interest in working on new builds. Builders want shortcuts everywhere.

Don't know about your areas but over here the paintwork on a new building only neeeds to come with 1 year warranty (or maybe even 6 months, not sure) if I recall correctly. So the builders just want it to look good, regardless if it lasts.


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## ridesarize (Jun 19, 2012)

The 3rd Coat said:


> Nowadays it's common practice in my country to do 2 coats of ceiling paint on ceilings without primer.
> That's why I have no interest in working on new builds. Builders want shortcuts everywhere.
> 
> Don't know about your areas but over here the paintwork on a new building only neeeds to come with 1 year warranty (or maybe even 6 months, not sure) if I recall correctly. So the builders just want it to look good, regardless if it lasts.


That sucks, it's our job to inform them though. It takes time to get through to em. Like one PT member teaches you have to train your clients too.


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## Brian C (Oct 8, 2011)

The 3rd Coat said:


> That was my original suggestion to the client but they didn't wanna pay for it. They're happy with blisters, I'm not going to argue with them.


Well that happens to me all the time. I tell them it will blister if the old paint is not removed but sometimes they go with another painter who gives them different advice.


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## ridesarize (Jun 19, 2012)

Dumb question here, what is weather board? Is that cedar lap siding, cement board "hardiplank", or what?
Thanks


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## The 3rd Coat (Aug 17, 2013)

lap siding, NOT SURE WHAT KIND OF WOOD THEY USE NOWADAYS.


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## Brian C (Oct 8, 2011)

we refer to weatherboards as pine timber cladding thats horisontal on a house and has been painted.


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## Toolnut (Nov 23, 2012)

My first reaction was the PVA primer as it seems like it causes me more problems than it fixes. Like flashing and adhesion on compound. But you said these were areas where you didn't use it.


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## Jmayspaint (Mar 26, 2013)

I have only seen the blistering problem as described in the OP a couple times. 
The only cause I could come up with was dust from drywall mud.


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## ptbopainter (Sep 10, 2013)

The only times it's happened to me was in houses where the previous owners smoked. They'd been there quite a few years (in both cases) but the current owners had been there for many years too just hadn't painted. I started priming but it bubbled up like crazy so I had to wash the ceilings walls and trim with TSP and that worked well. (Now I know to ask about smoking, doesn't show from the ground necessarily) Painting detective work :detective:
Otherwise it's happened on trim where the latex layer was bubbling off the alkyd layer underneath with no primer between, but in those cases it was easy to scrape off the latex layer with a putty knife. It was the humidity of the new primer that pulled up the latex layer but in one case it didn't start bubbling until it was really humid. 
I feel for you, that sucks! Especially when you've been putting in really good work filling holes, sanding etc. We are only ever as good as the worst painter that came before us, sigh, so unless we can undo what they did we suffer for it.


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## mudbone (Dec 26, 2011)

The 3rd Coat said:


> Not necessarily moisture. Most likely just poor adheasion of the previous coats. I did a weatherboard house exterior recently that had bubbling paint everywhere. Once I sugar soaped and pressure washed everthing, scraped back all the bubbles/blisters, primed and painted, new bubbles started forming, because of the added weight of the new paint film. I had told the client that the ideal solution is to strcoatsip the whole siding and start from scratch, but their budget didn't allow for that, so they're ok with the blisters here and there.
> 
> I suspect the same is happening in your case. Even if just one previous painter was a hack who didn't get the preparation right, bubbles/blisters will be a given with every paintjob afterwards.


Try 3 coats!:whistling2:


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## CApainter (Jun 29, 2007)

I've had this happen to me too.

Just a guess. It's likely due to poor adhesion of the existing coating and not moisture. The moisture from the new coating's vehicle, along with the resin properties of the new coating, can cling very well with existing water borne latex dry films. And, with the evaporation process and subsequent thermodynamics occurring in the curing process, pressure is created within the unseen void between the substrate and existing dry film. Also, being that latex and acrylic non conversion waterborne coatings are thermoplastic and not thermoset plastic, the existing paint film has the potential to soften to its original state which can be noticed in the form of a bubble.

Once the air cools and the evaporation process of the new coating subsides, the pressure in the bubble decreases allowing the film to rest in its previous state. Sometimes. 

I would also add that given the permeability of the existing latex paint film, moisture from new coating will enter the void mentioned above, and add to the pressures that can create a bubble.


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