stucco water repellent

Hi, I have colored stucco on my home, and it has been 12 years. It has never been painted. I plan to hire someone to paint the stucco with the original color. There is an area where the wall has some mildew stains on it. After I kill off the mildew, is there a product that can be mixed with the paint to help repel water? Or something that can be applied after painting, such as a water sealer?
Anyone has experience with Okon PaintBooster? http://www.okoninc.com/productPg-PaintBooster.asp . I heard mixing paint with any water repeller may weaken the paint.
I plan to use either Dunn Edwards EverShield or Sherwin Williams SuperPaint. Which one is better for exterior stucco?
Thanks
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In article

see here:
http://www.castlebri.com/documents/Stucco%20Care.pdf
and from another site:
"Ordinary house paint seals the pores on stucco. And as the stucco expands and contracts, the paint cracks, breaking the seal. Then water enters the stucco, gets trapped inside, and pretty soon the paint starts to delaminate. It doesn't take long before you're left with sections of bare stucco and patches of paintnot a pretty sight.
However, you can use elastomeric paint, which is formulated for stucco. It expands and contracts with the stucco and resists cracking (one brand is Valspar Duramax Elastomeric Exterior Masonry and Stucco Paint). Elastomeric paints also breathe, allowing moisture to get out. The best part: DIYers can apply it themselves.
If you don't want to paint your stucco, consider hiring a contractor to fog it. Fogging contractors use a special spray gun that combines a colorant with a thin cement slurry. Fogging is much faster and cheaper than dashing and lasts almost as long."
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On 12/4/2012 1:21 AM, Smitty Two wrote:

There are 2 kinds of advice for stucco.
One is for stucco over concrete block, common in the south, where the stucco is often painted.
The other is for stucco over wood frame construction, common in the north. I have always heard painting is not a good idea, as in Smitty's link. One reason is that the surface goes from a low maintenance stucco to a higher maintenance painted surface. There can also be problems if humid air migrates from inside the house out through the stucco, which depends on what the vapor barrier is. Paint needs to "breathe". There is a recent thread on stucco with a long post by nestork on stucco paint.
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snipped-for-privacy@hotmail.com wrote:

No idea which of the paints is better but any decent acrylic paint will work just fine on stucco.
We repainted our stucco over concrete block house about 2 1/2 years ago. The paint that was there was 14 years old and was chalking but not peeling. It was a middle grade acrylic.
The paint itself will repel water. Some people like to use a sealer before the paint so that the stucco doesn't suck up as much paint. Around here - central Florida - Original Seal Krete is popular for that purpose. It is just a clear, acrylic "paint" with minimal acrylic and no color. It can be applied with a garden sprayer. It is the same thing as your Okon Paint Booster but has less acrylic, price is around $12/gallon. http://www.seal-krete.com /
My suggestions for you would be...
1. Power wash 2. Optionally, apply sealer 3. Paint
--

dadiOH
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In additon to the good advice already give, there are products you can buy at the paint store that you can mix with the paint to help inhibit mildew. Don't know how well they work or last. But if the mildew took many years to develop, the simplest thing may be to just power wash it as needed.
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snipped-for-privacy@hotmail.com;2971719 Wrote: >

You should probably be aware that neither Sherwin Williams nor Dunn Edwards make any of the stuff they mix together to make their house paints. In fact, as of about 10 years ago, Sherwin Williams was using an acrylic binder resin made by the Rohm & Haas company called Rhoplex HG-95P to make their gloss and semi-gloss SuperPaint. Rohm & Haas was bought out by Dow Chemical in 2009, and Dow now markets that product under the same name:
http://tinyurl.com/bxwf8k7
The point here is that Dow will sell HG-95P to ANY paint manufacturer, just as other chemical companies will sell their pigments, coalescing solvents, rheology modifiers, defoamers, etc. to anyone wanting to make paint commercially, and if that manufacturer is competent enough to mix the chemicals in the recommended proportions, that manufacturer will make a paint just as good as SuperPaint.
And, the sales reps from every one of those chemical companies are continuously taking the managers at the paint manufacturing companies out to lunch to tell them about their latest and greatest offerings in the hopes they'll buy that resin, pigment or chemical. So, making the best paint in the world is not an engineering challenge; it's a management decision. Management has to decide whether or not the benefits provided by using a newer binder resin or pigment or chemical warrant the increased cost, and if so, they'll buy it to use in their paints. If not, they won't. It's as simple as that.
So, that's why it's often said that when it comes to paint, you get what you pay for. But, it's equally true that when it comes to paint, you often don't need everything you get. In my case, I own a small apartment block, and when I repaint apartments, I'm repainting them the same colour. So, does it make sense for me to pay extra for a paint with good hide? Not really.
So, instead of going according to whose name is on the can, you'd do well to just phone up the managers at any of the major painting contractors in your area and ask them what paints they've found work particularily well over bare stucco in your area. Most likely you'll find that there's no concensus of opinion as every manufacturer's top-of-the-line exterior latex works well, and the differences the paint company managers will spend most of their time talking about are if you're gonna use a sealer first, the weather conditions before, while and immediately after painting, the method of paint application (roller, spray, whatever), whether you're gonna put on a second coat or not and stuff like that.
All paint companies make the best paint they can put together for what they consider to be a reasonable price to pay for good paint. The difference is that they all have different amounts in mind when it comes to what good paint should cost. If you pay more for your paint, you generally get better paint, so the trick is to buy the most expensive paint from the place that sells it the cheapest. But, it's really whether you use a sealer to prevent the stucco from absorbing paint, that you're painting under proper weather conditions, and whether you put on only one coat or several that play the biggest roles in whether you run into any problems painting, and how long your paint job lasts.
I know that's not the simple one word answer you were looking for, but it's the correct answer to your question.
PS: This business about latex paints not being able to expand and contract with stucco, and the result being that the paint cracks and peels is a perfect example of why you can't believe everything you read on the internet. Wood is a natural material that expands and contracts with changes in it's moisture content usually caused by seasonal changes in temperature and humidity. The primary reason for oil based paints to come in both interior and exterior versions is that exterior versions will be made with more oil and less alkyd resin (called "long oil" paints) so they don't dry to as hard and brittle a film. That's done precisely so that the oil based paint retains enough elasticity to stretch and shrink with wood outdoors. Both interior and exterior latex paints have more than sufficient elasticity to stretch and shrink with wood outdoors, so the biggest difference between interior and exterior latex paints is the amount of additives (mildewcides and UV blockers, really) there is in each can. Wood can shrink by as much as 8 percent from "green" (recently cut) wood to oven dried, and that's vastly more dimensional change than you're ever going to see in stucco, especially due to thermal expansion and contraction. Exterior latex paints work fine on stucco; you don't need an elastomeric coating to paint stucco.
--
nestork


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