painting concrete floor


  #1  
Old 04-05-01, 05:11 AM
the butchers wife
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I am wanting to paint the concrete floor in the basement of my home. what is the best way to clean the floor for painting. do i need to prime first. the floor is in pretty good shape. just a couple of places where the floor is chipped. thought that i would use a cement caulking to fill that in. also what paint would you recomend. thanks
 
  #2  
Old 04-08-01, 04:55 AM
mikejmerritt
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the butchers wife and forum at large, I have a question on this post about the cleaning of the concrete in this basement. If I were outside I would etch it with muriatic acid, rinse, let dry and paint it with no primer. Outside I always use oil floor enamel. Is it safe to etch the floor and mop it clean inside? I know the mop will not fair very well. I know that etching is what lets the paint down into the concrete that has seen a lot of traffic. How does everyone prep these concrete floors inside?...Mike
 
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Old 04-08-01, 03:33 PM
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Mike, feel free to ammend or edit to suit.

The mop needn't suffer too badly. The method is neutralize with a Baking Soda wash; then repeated moppings with clean water. A final mopping with hot water with the mop wrung dry helps to remove the last traces, and the surface dries faster.

A nagging question: "How much Baking Soda"?
Since Muriatic acid is a dilute solution of Hydrochloric acid ranging from a 12% to 30% solution; the act of acid washing neutralizes some of the acid, and Baking Soda will act as a water soften for hard waters, (less is available for neutralization), the amount of Baking Soda will vary.

The sure way: test with litmus paper. (DIY source professional paint stores - becoming less common).
An approximation spanning most needs is one half of one small box of Baking Soda dissolved in 1 1/2 gallons of water for each 1 1/2 gallons of acid wash at a 10% solution.

Neutralized does not mean that the slurry is nontoxic or that it can or should be poured into a metal or porcelain plumbing fixture. If you must beat the devil: fill the fixture with water then run water while slowly mixing and draining. Do not pour directly into a toilet bowel. Mix small amounts in the tank instead. Regardless of disposal means dilute...dilute...dilute.
 
  #4  
Old 04-08-01, 05:07 PM
the butchers wife
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Is there anything else I can use other than the acid to clean the floor. I was hoping there was something less toxic as i have cats in the house. Thanks
 
  #5  
Old 04-08-01, 07:58 PM
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Yes, there is another less toxic more labor intensive way, however, I think you are misinterpreting the purpose of acid etching.

Acid etching is not a cleaning process in the standard sense, even though it has cleansing properties. Dirt and oil can be removed with many other common cleaners. In fact, if the concrete is dirty it should be pre cleaned prior to acid etching.

When concrete cures alkaline mineral salts bleed to the surface. Concrete finishing steps densify the surface layer into a protective skin. Acid etching quickly burns (oxides) the salts and opens microscopic pours in the surface plus it burns and dislodges embedded oil and dirt particles. Acid etching chemically sands the surface; it lowers the Ph at the surface by removing bleed salts, and it removes trace impurities.

A clean, dry, roughened surface, closer to Ph neutral, is desirable for paint adhesion. Not one set of directions on a paint container will state: "apply to a dirty, oily, wet, slick highly polished surface, with either a very high or a very low Ph". Many void the warrantee, in small print, for improper surface preparation.

Acid etching is an ineffective means of preparation on highly finished concrete. Fortunately most concrete is not polished smooth in the finishing stage. For highly finished concrete or in leu of acid etching mechanical sanding or grinding (wet or dry) are the alternatives. The normal abrasive is silicone carbide. It can be used wet or dry. Compared to acid etching it is very unpleasant and labor intensive. But if you must, then you must.
 
 

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