# Cover Stain failure



## hmac (Apr 22, 2014)

Hello all, new to the forum, 35 years of experience,

Last summer I painted two large exterior gates in Atherton, CA. They were previously painted with solid oil base stain. The stain had weathered severely, fading, mildew forming in some areas, and some bare wood.

I treated the surfaces with a bleach solution for the mildew, rinsed thoroughly, let dry for 48 hours, and sanded everything within an inch of its life. 

I then applied two coats of the new Cover Stain (water cleanup) because I was concerned about tannins and other stains. First coat of primer: sprayed and back-brushed into the wood. Second coat: sprayed, after the first coat dried overnight.

Then I sprayed two coats of Kelly-Moore 1245 Low Sheen Acrylic. After the first rain, the Cover Stain failed, forming large bubbles which when scraped off, go right down to bare wood in many areas. 
I am now looking at having to strip everything down to bare wood and start over - it will take 2 to 3 weeks at a minimum.

I will approach Kelly-Moore for help but I don't expect much. It may turn into a legal issue. I think some of these companies change their products and put them on the market without proper testing, and we get to be the beta testers.

I think the Cover Stain failed because of the new formulation. I've never had a problem with it in the past. Anyone else had a problem with this?

Any help appreciated.

BTW, I always use acrylic primers, such as 1-2-3 on exterior wood. Of course I regret not using it in this instance. I only used Cover Stain to be sure not to get a call-back for stain bleed later on.


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## Wolfgang (Nov 16, 2008)

Water based CoverStain = :no:


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## kdpaint (Aug 14, 2010)

I'd take 123 over water based Coverstain, and I don't think that 123 is great either.


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## Phinnster (Feb 20, 2013)

If the " new" cover stain is oil you should never use two coats
It traps moisture in 
So in theory it is your bad not some one else's
We thin our oil primers to allow the escape of moister yet we get the benefit of bleed control


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## Gough (Nov 24, 2010)

Phinnster said:


> If the " new" cover stain is oil you should never use two coats
> It traps moisture in
> So in theory it is your bad not some one else's
> We thin our oil primers to allow the escape of moister yet we get the benefit of bleed control


Also, gates and fences are more problematic than most surfaces. There's no way to keep water from penetrating, so you've got to provide a treatment/ coating that will let the substrate dry.


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## MikeCalifornia (Aug 26, 2012)

It is possible that your surface could not longer accept a coating. IE. prolonged exposure to moisture and the elements might have weathered the wood so bad that wood fibers just fall away from itself and are no longer a solid wood organism. 

Does the peel have wood fibers on the back? If so, the entire gate needs to be replaced, even if you sanded it down like you say, there is just no hope. Wood does not last forever if neglected.


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## Damon T (Nov 22, 2008)

I've never heard of the WB cover stain. Sorry to hear about that. Is it failing everywhere? Mostly on the horizontal surfaces? As previous post asked , are there wood fibers on the back of the peeling coatings? 
I'll touch base with our regional Zinsser rep and see if there's any widespread negative feedback on the product. 
Any idea what the moisture content of the wood was prior to priming?

I specifically exclude fences, decks, gates and galvanized metal from our exterior warranty. There are simply too many entry points for water.


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## Carl (Jun 18, 2011)

Why would you approach Kelly Moore if it was the Cover Stain that failed?


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## premierpainter (Apr 17, 2007)

The latex may have pulled the oil off of the wood. Oil becomes brittle over time and once you apply a latex over it, it could cause it to pull off. Sand the loose areas and apply again.
Have fun


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## richmondpainting (Feb 24, 2012)

I always use oil based cover stain on bare wood....I have no idea why anyone would use latex outside......


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## Carl (Jun 18, 2011)

richmondpainting said:


> I always use oil based cover stain on bare wood....I have no idea why anyone would use latex outside......


In some states, oil is illegal or is only sold in quarts. At some point, we will all have to use latex primers outside because oil will be gone.


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## Gough (Nov 24, 2010)

richmondpainting said:


> I always use oil based cover stain on bare wood....I have no idea why anyone would use latex outside......


Because sometimes it's the more appropriate material?


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## Phinnster (Feb 20, 2013)

Cover stain is a brittle drying primer
I am shocked that some people use to for large areas of bare wood
Would never be my choice


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## chrisn (Jul 15, 2007)

richmondpainting said:


> I always use oil based cover stain on bare wood....I have no idea why anyone would use latex outside......[/QUOTE]


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## journeymanPainter (Feb 26, 2014)

richmondpainting said:


> I always use oil based cover stain on bare wood....I have no idea why anyone would use latex outside......


That's all we use, unless it's new wood, or very badly damaged. Flats and satins are self priming, so if it's older wood, or little bits hitting it with your finish isn't bad

Sent from my SGH-T989D using Tapatalk


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## hmac (Apr 22, 2014)

Thanks for the replies.

As I said in my post, acrylic primers are my typical choice for exterior wood. I've done side by side tests with many acrylic vs. oil primers over 20 years, and the acrylics outlast the oils by far, especially on older, weathered raw and painted wood. Their breathe-ability and adhesion are superior. This is a debate for another time.

I only used the Cover Stain in this instance because the existing solid oil stain was weathered and badly stained. The Cover Stain seemed like the best choice at the time. I is recommended for exterior work and I have seen it perform satisfactorily in the past. I found out later that I could have purchased the original formula in quarts. I didn't know this at the time and chose the water-cleanup Cover Stain in gallons for the reasons stated.

We all know better in hind sight. I did not make this choice lightly, a lot of internal debating was involved. And of course I wouldn't use the product again.

I contacted my Kelly-Moore rep. because I have a 30 year relationship with K.M., where I bought the Cover Stain, and no relationship with the Cover Stain company.

My question again is, has anyone experienced problems with water-cleanup Cover Stain. To add to the confusion, it is not water-based, it is a hybrid oil base, with water cleanup.


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## PatsPainting (Mar 4, 2010)

hmac said:


> Thanks for the replies.
> 
> I only used the Cover Stain in this instance because the existing solid oil stain was weathered and badly stained. The Cover Stain seemed like the best choice at the time.


Sorry to hear your troubles but when you say you have 35 years experience and you decided on a water base primer on an existing surface that was oil is a little puzzling. 

In my opinion cover stain oil would even be a bad choice. Just dries to fast. Never penetrates, just sits there on the surface. A long oil would have been the the best choice.

It happens to all of us, when we over think things is where we make more mistakes then just going with our first thoughts.

Pat


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## Bender (Aug 10, 2008)

It's alkyd hybrid. We all rave about them as finishes. I see no reason why it shouldn't perform just as well as an oil primer.
Sorry hmac. I've only used it once for a wax bleed issue. I assume i had no problems with it, at least no callbacks yet...
It seemed to bond tenaciously.


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## victmor (Oct 12, 2007)

The "new" cover stain is in no way shape or form similar to the old oil based coverstain. Not even a similar product. To me it's a crime that they put the same label on completely different products. They should have just discontinued the the oil based product and marketed the new product with a new name to avoid confusion. jmho


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## hmac (Apr 22, 2014)

victmor said:


> The "new" cover stain is in no way shape or form similar to the old oil based coverstain. Not even a similar product. To me it's a crime that they put the same label on completely different products. They should have just discontinued the the oil based product and marketed the new product with a new name to avoid confusion. jmho


Thanks, man. You are right on the money.


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## putlotson (Feb 22, 2012)

I think part of the confusion is created due to location. Manufacturers are dealing with different eco laws in different states and provinces. For example the hybrid waterborne Cover Stain is not available here in British Columbia. I'm still using the oil that is still sold here in gallons etc. That said about 3 years ago the oil went through some kind of viscosity change as if they were messing with the formula. For example if local laws state that the emissions must be lower than a certain level then if they increase the solids in the can the emissions drop below the allowable level. The only problem is you have to add solvent for penetration and workability at the point of application and you end up with higher emissions anyway! With respect to the gate problem: YOu may have a combination of issues. You say these gates are big, needed bleach for excessive mildew (shady area?) and that you rinsed and dried for them 48 hrs. Did you h2o meter them at the bottoms and the joints first? Controlled pressure washing instead might have knocked off loose paint and dead wood fibres giving you a better chance a penetration. If the peeling is on the bare spots the primer did not penetrate where it needed to to withstand shrinkage & expansion and possibly thinning the primer would have helped. I've had lots of problems with fast drying waterborne coatings that tend to "glove" over an old coating instead of "gripping" onto it. It looks fine but down the road you can peel it off in sheets. Benjamin Moore Aura will do that over a smooth surface subject to exp/contr like garage door panels. If the peeling was over multiple old coatings and it did "girp" and not "glove" it then I'm with PremierPainter and his "tension failure" theory. Entire houses have been known to lose multiple coats of old oil after the application of a high quality acrylic. I was working with a paint company last year and the owner of it was painting his own 70 year old house. When the sun came over the top in the afternoon he watched in horror as the green siding started to swell up into basketball sized bubbles. Then it hit his newly painted black ship plank front door. It stripped it down to the bare wood in a couple of hours. Because it was his own house he had company logo signs all over the lawn and all his company trucks in front! they got pulled pretty quick!


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## Stonehampaintdept (Jan 10, 2013)

One thing I think some of us forget is the age of the wood to begin with. Building materials now are all new growth designed to grow bigger and faster. This leads to a number of problems with not only tanin bleed but pitch, sap, lignin etc. bleeding for years after installation until it finally dries out. Of course we don't let it dry out and leave it exposed for those years, it would rot too fast.
As breathable as the best latex primer/paint is, it still traps moisture to some degree and prolongs the "drying peroid" of the wood. It's a cross we must all bear until everything is made out of plastic.


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## PaintEmUp (Sep 24, 2014)

Wolfgang said:


> Water based CoverStain = :no:


Yes cover stain is oil based. I've never seen a latex version.

Cover stain is for covering water and mold damage. Latex will be pointless to cover water and mold. As mold cultivates in water, hence water based being a no no. Oil will prohibit mold growth exponentially better.


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## putlotson (Feb 22, 2012)

*Coverstain Varieties*



PaintEmUp said:


> Yes cover stain is oil based. I've never seen a latex version.
> 
> Cover stain is for covering water and mold damage. Latex will be pointless to cover water and mold. As mold cultivates in water, hence water based being a no no. Oil will prohibit mold growth exponentially better.


Hi PaintEmUP. To set the record straight Coverstain currently is sold in 4 varieties. 3 are oil based and all 3 have different TDS sheets. Apparently Zinnser does not recommend thinning any of them. News to me.... They also have a water based version. All 4 versions have very similar labels. You can see them all at this link. http://www.rustoleum.com/en/product-catalog/consumer-brands/zinsser/primer-sealers

With respect to your comment about oil paints being better than latex as mold inhibitors: It's my understanding and experience mildew and other spores can thrive just fine in alkyds. The difference is if the paint has mildewcide in it or not. Mildewcide is expensive so it is usually found in quality paints in quantities of less than 2%/vol. Because of the small amount it is sometimes not listed as an ingredient. The interesting fact about mildewcides is that some people are very sensitive to THEM. Instead of it benefiting certain people by reducing the presence of mildew it can CAUSE them health problems similar to the ones caused by the mold it is supposed to suppress. (From The Homeowner's Guide To Mold by Michael Pugliese) For exterior products mildewcides are designed to leach out of the paint and do their job until they eventually wear off allowing midew to grow. Another reason why selling a customer on 2 coats is always a good idea.


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