Author Topic: Painting a Concrete Floor--Do I need to Etch?  (Read 27660 times)

TPGW

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Painting a Concrete Floor--Do I need to Etch?
« on: May 27, 2015, 10:24:54 AM »
I am planning on painting the old concrete floor to my basement.  We are in the process of finishing half the basement and putting a bathroom down there.  To save some money we are planning on painting the floor and using large, inexpensive area rugs; it's possible that we'll put in wall to wall carpeting in the near to medium term.

It's an old concrete floor in a house built in 1928.  It's completely dry--we have tested with a taped down plastic bag.  It was painted once at some point in the past and that paint has mostly flaked off.

The current plan is to sand and clean the floor thoroughly (from what I understand the cleaning is a very important step), and then paint.  I'm still researching products to see what is best--any suggestions would be appreciated.   

Sources seem divided online about whether we need to etch or not.  The concrete is old and somewhat weathered.  Is etching absolutely necessary, or could I skip that step?  I'm not opposed to doing it, but don't want to do anything unnecessary.

Thanks for the help.

Bob W

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Re: Painting a Concrete Floor--Do I need to Etch?
« Reply #1 on: May 27, 2015, 10:29:35 AM »
Sand it?  Don't get that step.

I'm in the process of "staining" our concrete office floor.  I did buy the etcher and will use it.   I'm not sure our floor is sealed or just polished?   Either way the etching should make the concrete porous and your paint or stain will adhere. 

If you have the time do a little more research.  There are some very cool paint/stain outcomes for basement floors.     

It is a big job.   

Have fun. 

TPGW

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Re: Painting a Concrete Floor--Do I need to Etch?
« Reply #2 on: May 27, 2015, 10:34:53 AM »
Thanks.  The old paint is very flaky--I'm hoping running over the floor with a sander will get most of it up.

I will take a look into stains as well. 

pjm123a

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Re: Painting a Concrete Floor--Do I need to Etch?
« Reply #3 on: May 27, 2015, 04:52:49 PM »
I just did something similar in 2 places outdoors. I am in FL and concrete being porous absorbs water and you end up with black mold. This causes a requirement for periodic power washing. I wanted to do something to reduce eliminate the mold/power washing cycle. I got some advice at my local Lowe's from a crusty old guy who said he was a retired painter. So far his advice seems to have worked out. Area 1 is a concrete driveway apron. I power washed and got it real clean. Then I etched with a solution of 50% muriatic acid and water. Just put it in a garden spray can and sprinkled it around. It sizzled and foamed for a while. I let it sit for half hour and then hosed it off. Then I let it dry real good (one week with no rain in the hot FL sun). Then I put down 1 coat of zylene based concrete stain (they sell it at Lowes). Let it sit another week. This looked OK but not great. The Lowe's guy warned me that I would probably not be happy with 1 coat. Then I put down a second coat. That made a BIG difference then. I let that dry a couple days then went over it with an oil based concrete sealer. Lowes also sells this. I think it is made by a company called H&C. The second area was a concrete patio. This had been painted in the past with what appeared to be house paint and was flaking off all over the place in some spots or was down to bare concrete in other. The power washing and etching did a pretty good job of cleaning all of it up. In this case because it will not be driven on I used a latex based floor and porch paint instead of the xylene based stain. Also, after using the sealer the first time around the finish was a bit slicker than I liked. So when I did the patio I mixed some silica stuff (also from Lowes) in with the sealer and it gave it a little grit which makes things less slippery. I only did this work a couple of months ago so I have no idea how long it will last but so far I am quite pleased.
« Last Edit: May 27, 2015, 04:57:49 PM by pjm123a »

MWOverlander

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Re: Painting a Concrete Floor--Do I need to Etch?
« Reply #4 on: June 06, 2015, 07:19:46 AM »
If this is a temporary solution until you are able to get carpet, then I would not personally worry about etching the floor.  You just need to have the expectation that at some point moisture could become an issue with older concrete, which could potentially lead to the paint popping/peeling. 

If this could become more of a permanent solution, then removing all the current coating and etching would be ideal.  The process of etching removed any sealers currently on the floor and provides a slightly rough surface for the paint to adhere to.  Since this floor is from the 20s,  I highly doubt its as smooth as a babies bottom.  If you were using an epoxy floor system, then I would strongly recommend etching as a bare minimum. 

Milspecstache

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Re: Painting a Concrete Floor--Do I need to Etch?
« Reply #5 on: June 14, 2015, 01:19:13 PM »
Sanding may disturb lead in the paint.  Is the existing paint white (or a close shade thereof)?

Bob W

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Re: Painting a Concrete Floor--Do I need to Etch?
« Reply #6 on: June 14, 2015, 01:45:58 PM »
Sand it?  Don't get that step.

I'm in the process of "staining" our concrete office floor.  I did buy the etcher and will use it.   I'm not sure our floor is sealed or just polished?   Either way the etching should make the concrete porous and your paint or stain will adhere. 

If you have the time do a little more research.  There are some very cool paint/stain outcomes for basement floors.     

It is a big job.   

Have fun.

Finally got around to doing a test area at the office.   I etched a patch and then stained over it and a noneteched patch.  Will let it dry tonight and see if there is a difference.  (etching really sucks as the acid is dangerous and a hassle to handle and use).   It is in a part of the building not seen by the public but has high traffic.  So I will let it set for a couple of weeks and see how it goes.   Really the staining is very easy and quick.   So even if we end up restaining every year that wouldn't take long or cost much. 

Will keep everyone posted.

TPGW

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Re: Painting a Concrete Floor--Do I need to Etch?
« Reply #7 on: June 17, 2015, 07:56:33 AM »
I've spent the last 2 weeks stripping the paint from the concrete.  Sanding, as predicted by others, wasn't effective.  Stripping paint from a large concrete basement floor is a pretty miserable task, but it's finally finished.  I have etched about 50% of the stripped concrete and will hopefully get to the rest this weekend.  Then painting some time next week, to coincide with the finish of the rest of the work in the basement.   

There is some type of red substance left in areas of the concrete.  Not sure what it is.  It didn't react like paint to the stripper, but it did come up to some degree along with the green paint I stripped.  Maybe some kind of sealer?  I have no idea. 

It'll be interesting to see how the paint takes. 


Rosy

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Re: Painting a Concrete Floor--Do I need to Etch?
« Reply #8 on: July 02, 2015, 06:30:05 PM »
We etched and stained our front porch and carport area - concrete is original from 1957. I wanted it to look nice so we taped off areas to make it look like a rug and even stenciled in a walkway and some kokopelli images - still looks great five years later.
I mixed a couple of the colors and even spray painted some areas a different color (like the border for the rug:) - all in all it looks like a nice custom job. A lot of work, but worth it in the end.

dragoncar

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Re: Painting a Concrete Floor--Do I need to Etch?
« Reply #9 on: July 02, 2015, 07:32:29 PM »
Bob, what products are you using?  Would love a trusted review, since there's a lot of suspect information out there.