# peeling paint on concrete floor



## SeanR (Sep 4, 2011)

We have a blackbox with a concrete floor. When we paint it for shows, getting the paint to not flake off easily is a challenge. For example, a set piece on the paint that is jostled will pull the paint up. Any suggestions on how to deal with this without repainting before every show? This should also not be a permanent floor treatment, since we will want to paint the floor back to black after the show.


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## mstaylor (Sep 4, 2011)

Sounds like you are using the wrong product on the floor. Is there a clear finish on the concrete that you are trying to cover? If not it may be either deck paint or other type of oil based finish and you are trying to cover it with latex, which will cause flaking. You need to identify the finish on the concrete, then decide what should be used to adhere to it.


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## josh88 (Sep 4, 2011)

what Michael said, if the floor has a sheen/glossy surface paint won't want to adhere to it as well. There are also options like what is typically called porch and floor paint which is formulated to have a stronger bond on smooth cement floors as well as being more durable to walk on and more scuff resistant. Another option would be to put down bonding primer first since that will greatly increase the adhesion factor.


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## SeanR (Sep 4, 2011)

Thanks guys. It is worth pointing out that there is no special finish on the floor.


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## josh88 (Sep 4, 2011)

Sean I don't know where exactly you are in columbus or who you get your stuff from but awhile back I worked for the Home Depot in Dublin over on sawmill and while I generally prefer lowe's that store is a great one to work with. I've done theatrical painting and commercial sales for paint but if you continue to have problems and they are an option maybe run over there the paint guys they had really knew their stuff.


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## venuetech (Sep 4, 2011)

often it will look like there is nothing there, concrete often has a clear sealer applied. this likely would have been applied some time after the slab was poured.


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## Van (Sep 5, 2011)

Painting any kind of floor can be a real challenge. There are a large number of details and factors that can go in to a floor treatment failing or suceeding. It may not appear that ther is any type of coating or finish on the floor but often times different plastic polymers are mixed into concrete to help it cure or to change it's strengh/flexibility. The most common way to overcome issues like this is through proper preperation of the floor. Beyond a siple sweep and mop or power wash, Surface prep is the number on reason that painted concrete floor finishes fail. What is really necessary is a cleaning with muriatic acid. There are several brands available at hardware stores and home centers. Muriatic acid essentially etches the top layer of concrete roughing it up so that the binding agents of a paint have something to grab on to. I can't stres enough how important it is to read understand and follow the manufacturers directions. Muriatic acid is extremely dangerous, toxic and icky. 
Second most common reason for floor paints to fail: Moisture. Bet you thought that concrete floor was solid as a rock didn't you ? Well it is... sort of, it's as solid as a very porous rock. water can go right through it. and under certain conditions water can even be drawn trough it by the act of improperly sealing the top surface. I suggest a really good masonry sealer, ther are several on the market.
Third biggest reason fo failure: point loads. Let's face it no matter what you put down it going to be layer on top of an extremely hard surface if you use small areas to carrry the load of a set peice or tool or peice of equipment the material is going to flake, chip, or scuff off. So choose your materials carefully. 
There are a ton of floor paints available but if you really don't want to have any issues with your floor I would suggest stripping it with acid then laying down an expoxy floor treatment like that which is used in garages. It's expensive, but there really is no substitute for a good base layer. You can paint on top of it if necessary and most paints stick to it rather well.


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## Les (Sep 5, 2011)

Valspar makes a great latex satin porch and floor paint. It can be tinted to just about any color (Dark Kettle Black, for standard rep color). It's about the same price as any other paint (between $20 and $30 a gallon). A gallon yeilds about 350sq. ft of coverage per application.


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## mstaylor (Sep 5, 2011)

Van said:


> Painting any kind of floor can be a real challenge. There are a large number of details and factors that can go in to a floor treatment failing or suceeding. It may not appear that ther is any type of coating or finish on the floor but often times different plastic polymers are mixed into concrete to help it cure or to change it's strengh/flexibility. The most common way to overcome issues like this is through proper preperation of the floor. Beyond a siple sweep and mop or power wash, Surface prep is the number on reason that painted concrete floor finishes fail. What is really necessary is a cleaning with muriatic acid. There are several brands available at hardware stores and home centers. Muriatic acid essentially etches the top layer of concrete roughing it up so that the binding agents of a paint have something to grab on to. I can't stres enough how important it is to read understand and follow the manufacturers directions. Muriatic acid is extremely dangerous, toxic and icky.
> Second most common reason for floor paints to fail: Moisture. Bet you thought that concrete floor was solid as a rock didn't you ? Well it is... sort of, it's as solid as a very porous rock. water can go right through it. and under certain conditions water can even be drawn trough it by the act of improperly sealing the top surface. I suggest a really good masonry sealer, ther are several on the market.
> Third biggest reason fo failure: point loads. Let's face it no matter what you put down it going to be layer on top of an extremely hard surface if you use small areas to carrry the load of a set peice or tool or peice of equipment the material is going to flake, chip, or scuff off. So choose your materials carefully.
> There are a ton of floor paints available but if you really don't want to have any issues with your floor I would suggest stripping it with acid then laying down an expoxy floor treatment like that which is used in garages. It's expensive, but there really is no substitute for a good base layer. You can paint on top of it if necessary and most paints stick to it rather well.


Van makes a good point about etching the floor. Remember you will likely not be using the muriatic acid straight. When you go to mix it with water, add the acid to water not the other way around. Learned that the hard way.


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## Chris15 (Sep 6, 2011)

A perhaps useful mnemonic:
Always remember to do what you oughta
Add acid to water.


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## josh88 (Sep 6, 2011)

it should be noted that while muriatic acid works the best, if you're going to go so far as etching the concrete they also make powdered etchers that you can get from the typical box stores like lowes and you just add the powder to water and it does the same thing. Some people don't like the idea of having acid sitting around afterwards so the powder is a better choice for them.


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## Chris15 (Sep 6, 2011)

josh88 said:


> Some people don't like the idea of having acid sitting around afterwards


 
A packet of bicarb soda from your friendly neighbourhood grocery merchant can put a fairly quick end to that problem...


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## Van (Sep 6, 2011)

josh88 said:


> it should be noted that while muriatic acid works the best, if you're going to go so far as etching the concrete they also make powdered etchers that you can get from the typical box stores like lowes and you just add the powder to water and it does the same thing. Some people don't like the idea of having acid sitting around afterwards so the powder is a better choice for them.


 
The powder is Muriatic Acid, in it's anhydrous form. it's no safer or more dangerous than then the liquid, essentially.


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## headcrab (Sep 6, 2011)

I once went to get some of said acid, and while asking about its location I called it hydrochloric acid (which it is) and apparently few people know that, of which the salesperson was not one...


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## Les (Sep 6, 2011)

headcrab said:


> I once went to get some of said acid, and while asking about its location I called it hydrochloric acid (which it is) and apparently few people know that, of which the salesperson was not one...



90% of the general public calls it Muriatic Acid, though the chemical name is hydrochloric. I work in a big box paint department, and I'll admit that I didn't know that until I read the label more closely a few months ago. There are a lot of things to learn in any given department, and knowing it all for $13 per hour is a tall order (Muriatic acid is about 1% of department sales) . Most people who purchase it already know what it is used for (etching, swimming pools, etc), so we don't get a ton of hands on experience with it. I always say that I learn more from my customers than I do from any vendor training session or computer course. One of which would be a scenario such as you describe. 

So, feel good that you taught the associate something; that's how we get better .


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## Van (Sep 6, 2011)

Hydrogen Chloride or HCL IS the Chemical name. Muriatic Acid is the common name which dates back to the year 800 when Alchemists obtained HCL by disolving common table salt < NaCl> in a solution of Sulphuric Acid < H2SO4> . Muriatic means, in the Latin, "Of or Pertaining to the Salt air, or Brine." It is also refered to as Acidum Salis.
Now, can we get back on Topic ?


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## josh88 (Sep 6, 2011)

I meant that when I worked for the box stores people would often come in and not want a whole gallon of the acid and that they found the powder to be an option they liked because A it was a smaller quantity and B they liked the idea of powder in a box over liquid in a container that they could spill. Granted most of the folks here are a little better versed in certain things that the average consumer but most of the average do it yourself types wanted the easiest hassle free way.


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## venuetech (Sep 6, 2011)

while we are on the subject of etching.....
I will just toss out that Aluminum should be etched before painting. this can be done with rag dampened white vinegar.


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## gafftaper (Sep 5, 2014)

I have this ugly 80'x10' bare concrete floor hallway backstage. One side of the hall is the theater, the other side is the greenroom, office, and shop. A few years ago there was an accident with a genie lift falling over and so one part of the hall even has a fantastic battery acid stain. The rest of the school (built 4 years ago) is all that concrete which has been buffed out and sealed to look really nice and pretty. Based on the wear in the doorway, it appears my hallway is made of the same stuff, it just never got buffed and sealed.

So we want to paint the floor. We were all drooling over the idea of doing it in a really high gloss epoxy in a deep purple (school color). But I have the problems above it won't stick without either: Acid etching, getting it shot blasted to rough it up, or use a fancy bonding primer layer first.

There's no way I will get approval to use acid etching in a school, plus it's going to be really hard to find the time that i can shut the hall down. Getting it shot blasted would require a lot of extra money and a lot of red tape with the district facilities department, so that's out. So I'm left with primers. The local paint shop said there really is no primer designed for bonding paint to a smooth concrete floor. They have a primer that they sell for bonding paint to glass and other very smooth surfaces. However, it's not designed to be able to withstand walking on and rolling set pieces in and out of the shop over. So the paint guy says it's a shot in the dark as to how well it will work.

Have you used a bonding primer to paint a smooth concrete floor? How well did it work. I don't mind repainting the floor every year or so, I do the stage deck every 6 months already. However I don't want to spend that much money only to have the paint peel up in long strips the first time a move a piano across it either.


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## kicknargel (Sep 8, 2014)

I have paint spills and such on my concrete shop floor that have been there forever. Perhaps doing it in a series of spatters and/or washes would give you some forgiveness with wear, as opposed to a pristine solid color.


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## gafftaper (Sep 8, 2014)

kicknargel said:


> I have paint spills and such on my concrete shop floor that have been there forever. Perhaps doing it in a series of spatters and/or washes would give you some forgiveness with wear, as opposed to a pristine solid color.


That's a good point. The spilled paint never seems to go away.


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