Prepping smooth concrete wall for paint

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Prepping smooth concrete wall for paint

Postby ninjadog » Wed Dec 07, 2016 9:13 am

My builder made one section of wall as a smooth, lacquered concrete. It looks nice, but unfortunately, it becomes extremely hot. This is going to need to be painted to solve this problem. What is the best way to prep this wall to accept paint?
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wall.jpg
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Re: Prepping smooth concrete wall for paint

Postby Sometimewoodworker » Wed Dec 07, 2016 5:42 pm

ninjadog wrote:My builder made one section of wall as a smooth, lacquered concrete. It looks nice, but unfortunately, it becomes extremely hot. This is going to need to be painted to solve this problem. What is the best way to prep this wall to accept paint?

Sandpaper :(
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Re: Prepping smooth concrete wall for paint

Postby ninjadog » Wed Dec 07, 2016 5:52 pm

Thanks for the reply. I tested a small area of it using a sander and the roughest grade of paper available. It will definitely remove the lacquer, but my concern is whether paint will take to the wall. It was still this smooth concrete. I've seen people attempt to paint over smooth/polished concrete and it just started peeling away rather quickly. Before I start doing anything serious to the wall, I want to have a pretty good idea that what I'm doing will actually work.
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Re: Prepping smooth concrete wall for paint

Postby groucho » Wed Dec 07, 2016 6:34 pm

Your polished concrete wall looks great. I have polished concrete walls on my outdoor terrace, and sections of all four interior floors, I sealed them with CIC A-100 Polyurethane .. they are beauitful. If you want to paint your wall you could use TOA roof seal with UV protection, comes in white and grey. Just prime and paint.
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Re: Prepping smooth concrete wall for paint

Postby ninjadog » Wed Dec 07, 2016 7:48 pm

Truth is I don't "want" to paint the wall. I want to stop the heat. The painted wall right next to this stays nice and cool. This wall just bakes in the heat and radiates into the bedroom inside. If there was a solution to deal with the heat issue without painting, I would definitely do that instead.
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Re: Prepping smooth concrete wall for paint

Postby ninjadog » Wed Dec 07, 2016 8:18 pm

The attached photos show the difference in temps on a mild day of 26 degrees celsius.
Attachments
15045306_10154726873628156_1122539430_o.jpg
This is the painted wall on a day where the air temp was 26 degreees
15064025_10154726874173156_1263172963_o.jpg
This is the polished concrete wall at the same time
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Re: Prepping smooth concrete wall for paint

Postby Sometimewoodworker » Sat Dec 10, 2016 5:39 pm

ninjadog wrote:Thanks for the reply. I tested a small area of it using a sander and the roughest grade of paper available. It will definitely remove the lacquer, but my concern is whether paint will take to the wall. It was still this smooth concrete. I've seen people attempt to paint over smooth/polished concrete and it just started peeling away rather quickly. Before I start doing anything serious to the wall, I want to have a pretty good idea that what I'm doing will actually work.

It is quite likely that they used a watered down paint.

My suggestion is to first throughly clean the wall, it may have accumulated some grease, then sand to provide a key then use a good undercoat do not dilute it. And of course white is the best colour.

Professionals would use an acid etch but the cleaning and sanding does the same job
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