Prime Paint Caulk Questions

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  #1  
Old 03-26-18, 07:35 PM
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Prime Paint Caulk Questions

I have two scenerios I would like to get some advice on.

CASE I
I have some cracks in the exterior concrete block walls which I have repaired with a polyurethane sealant. During the repair I have widened the crack some with an angle grinder and scraped off some loose paint on the stucco. I am now ready to repaint the repaired section. The finish paint is acrylic paint. Is it better to use an oil based primer over the caulked crack (since it's polyurethane) then put paint over the oil based primer? or should I just use a water based primer? I have both so just wondering what's best. Also, should I put two coats of primer and 1 coat of paint, or 1 coat of primer then two coats of paint?

CASE II
Replaced a window and refinished stucco around the exterior of the window. So I am now looking at raw stucco (been sitting for a few weeks) adjoining the aluminum window edges. What is the best way to seal the joint? Latex caulk or paintable silicone caulk? Since I need to prime and paint the raw stucco anyways, should I caulk then prime/paint or should I prime the stucco up to the edge of the window, then caulk the joint, then finish paint last?

Thank you.
 
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Old 03-27-18, 03:43 AM
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It should be fine to apply latex over cured urethane caulk. The bigger question is the condition of the existing paint, is it chalky? Latex paint doesn't adhere well to chalk! If/when all the chalk can't be washed off you need to use either an oil base primer or add Flood's EmulsaBond to the first coat of latex.

I've always used a paintable caulk to bridge the gap/joint where the stucco meets the window. It's best to caulk between the primer and finish coats.
 
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Old 03-27-18, 07:23 AM
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The existing paint is not chalky. However, I used a grinder to widened a little the crack so I can get the poly sealant deep into the crack, and I scrapped off loose paint around the crack. Also in some places I feathered the caulk a little around the crack. So I am looking at a patch that's long about 4" wide, containing some poly caulk, care stucco, old paint combination. So apply latex paint directly or prime over it first?
 
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Old 03-27-18, 07:41 AM
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While it's best to prime, many do not and it works ok. Many yrs ago we thinned the finish paint about 10% and used it for a primer.
 
 

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