How to Tape Out Flagstone Overlays Like a Pro

Stamped concrete is on the rise. Why? Well, those rubber stamps are pretty easy to use and can rapidly push patterns across a large surface area. But lots of guys do stamped concrete simply because it IS easier. The result? A lot of surfaces that look... well... kinda the same.

To survive in today's marketplace you need to stand out. You need to offer the same trusted and popular systems but with your own style infused. And that's something you're just not going to achieve with a stamp.

No one wants a cookie-cutter surface. And unless you invest in lots and lots of different stamps, that's what you're going to get. That's why purists in the field of decorative concrete overlays still rely on good ol' silver cloth tape to create those really wild designs, the kinds that no one else has. But how can strips of what essentially looks like duct tape really turn a floor into something truly unique?

Take a look at it this way. The key to really good flagstone lies in two factors: stones and grout lines.

Grow Some Stones

When you think of traditional flagstones you probably think of stones. At least you should. But setting real flagstones is tedious, backbreaking work. And there's no guarantee the stones will keep from shifting or coming loose, or cracking, or chipping, or discoloring or fading... blah, blah blah.

Okay, enough of the overlay selling points. We all know the benefits of a good overlay. But why the emphasis on the word 'stone'?

The answer is easy to see but very, very easy to forget. Especially when you are the guy down on your hands and knees taping out the floor. It's tedious, you're tired, and you just want to get the tape down so that you can move on to the texture. But THIS step, this very step right here, is the key component, the magic bullet that can make or break your floor.

Flagstones are stones. Duh, right? But how easy is that to forget? If you just start at one end of the floor and start slapping down tape all over the place, creating all kinds of pointed intersections, or swervy lines, or places where three to four tape-ends join, then your floor is going to look like... well, I'm not going to use the first word that comes to mind. Let's just say it's not going to look very professional.

Stones, baby. Stones.

Stop what you are doing. Take a minute (or two) to REALLY take a good look at the entire surface. Is it a big square? Chances are it isn't. What are the entry points? Is there anything in the middle of the surface that breaks it up (like a fountain or planter)? Are there expansion joints? Do steps come into play?

Stones....

If you were a stone, what would you look like? Would you be perfectly square? Maybe. But if you are then all of your neighbors should be too. And then you really won't be flagstone anymore. You'd be more like slate, or a cobble. That's cool. But we're talking about flagstones here.

Flagstones are generally shaped like four- to five-sided polygons. For those of us who had to take geometry several times, polygon is a fancy name for a shape made from varying line segments joined together to form a closed shape. And when you are talking about flagstones, four to five sides are about all you need. Any fewer sides and you got a triangle, too many and you got... well, you just get a sloppy mess!

Now, draw a cool stone in you mind. Got it? Cool. Now carry that stone (and a good roll of 1/2” silver cloth tape and a fresh razor knife) over to one of your entry points. Why start there? Why not? I mean, that's where people are going to be walking, right? And if you were going to step out onto a flagstone surface wouldn't you want your first step to be on a really cool stone?

Okay, now see the stone in your mind. Set your first line. Doesn't have to be straight, just make sure you don't lay it wavy. Worried about too straight a line? Fret not, grasshopper. We'll take care of that later. A good tip: lay the tape out still on the roll. By that I mean don't cut it and then lay it down. That's what the razor knife is for. When you have it stretched out to where you want it, just hold the razor knife firmly down across the tape and pull up. Don't slice. The blade will make the cut for you and you won't disturb the tape or get your fingers all over the sticky side, which can make the tape curl up or come off the surface.

Keep going. Get that first, cool stone down. And don't forget to leave plenty of extra tape near the edges of the slab so that you can pull it later.

There. Your first stone. Stop. Stand up. Is it cool? Cool. Keep going.

Stone by stone...

Sounds tedious, and to a certain extent it is. But if you take EACH AND EVERY stone into consideration and progress across the floor in this manner, taking into consideration all the unique curves and angles of the floor as you go, you will achieve a much more realistic looking pattern.

Size it Up

So what about the size of each stone? Should you use the same size stone across the whole floor? Should you mix in all different sizes? Should you make some pointy?

Believe it or not I can sum this up in once sentence. [Deep breath] Here goes...

Establish the size for a LARGE stone. The exact size of a large stone depends entirely on you AND your client. Got that? Not just you. Take the client out there and have them look at the stone, the one ACTUALLY on the slab. Trust me on this one. Come into agreement on what the biggest stones in your pattern will look like. This will save you LOTS of problems.

The rest is easy. Because once you have that large stone agreed upon, you just need to make (in your head) two more versions of that stone: a MEDIUM and a SMALL. Oh yeah... and throw in a cluster of MINIS every now and then.

Okay, not one sentence. Sorry.

Rough Up the Edges

If you take the time to follow this method you will find that your floor actually does look like you laid stones. Because you really kinda did! But most people stop right there. And why not? At this point your pattern probably looks pretty cool! But now is the time to take it to the next level, to the max, to pump up your pattern, to...

Okay, enough 80s clichés...

That razor knife in your hand offers a simple solution. Remember those straight edges? Just use your razor knife to take little slices off of each side of the tape. Careful, I mean LITTLE slices. You don't want to cut though the width of the tape. And don't swerve your knife as you cut. Trust me, you'll remember this when you are about half way across the surface, and you are tired, and just swerving that knife seems so, so tempting. Take little cuts. It doesn't take much. And make sure to gather up all those snipped pieces, you don't want those stuck on the finished surface.

And BAM! Now your flagstone pattern is complete! And with a little time (and lots of patience) you've now given your client a surface that no one else has!

Parting Tips

• Avoid making intersections where more than three lengths of tape join. This will create pointy stones.

• Make absolutely sure each and every length of tape overlaps the next. This way when you pull the tape it will all come free as one pattern and you won't have pieces stuck in the floor.

• Before you apply your texture coat, mix up some loose mud. Pour it in a cup and walk across the entire surface with the cup in one hand and a chip brush in the other. This way you can 'paint' all of the tape lines down, which will help keep them in place when you trowel the texture.

• Don't pull your tape too tight or this will 'bend' the pattern and pull it off of the surface.

• Do a final check to make sure EACH AND EVERY piece of tape is actually sticking to the surface.

Was this information helpful? I certainly hope so. You can learn all about decorative concrete overlays and more in The Book of Decorative Concrete Coatings.

How to Prep Concrete for an Acid Stain

By Ted Uram

It's really hard to find anyone who can't appreciate the wicked coolness of an acid-stained floor. And while the colors are not as plentiful as what can be achieved with other, non-reactive staining alternatives, nothing beats the subtle complexity of the acid-staining concept – acid stains literally burn in a lasting coat of beauty. And they achieve this in a very simple way.

With all the fluxuating trends and shifts in floor coating technology, acid stain floors continue to remain popular. Why? Simply put, no other floor technology achieves results quite like acid staining – that mottled look, that inconsistent yet strangely appealing speckle of color. Try and faux this and you will be hard pressed, try a non-reactive alternative and you may be let down.

What's Going On?

To understand the prep for an acid stain you must first understand how all of this is happening. Here's the basic concept:

Acid stains are made from blending small amounts of reactive metallic salts with acidic agents, such as muriatic or hydrochloric acids. The metallic salts provide the color while the acidic agent burns it in. But what does all this really mean? What is really happening?

The uppermost layer of concrete in good condition contains a concentrated crust of cement paste that is just not present in rest of the slab. This occurs during the concrete finishing process when excess water is bled to the top, and the top portion of the slab floated to make it nice and smooth. It is this thin layer of material that is reacting with the acid stain – not the rest of the slab.

I'll say it again – the uppermost crust of the concrete slab is where acid stains react.

Okay. Then the rest should be common sense. Right?

Read on...

What Went Wrong?

Talk to any coatings guy (or gal) and you will hear the same thing: surface preparation is key to any successful coating. How true. But sometimes, in an effort to simply do the right thing and get that surface prepped really really well, some folks can overdo it.

Take this into consideration:

“I don't understand! I did everything right. The floor was in pretty good condition. Had a few spots where something got on it, but I cleaned it all up really well, scrubbed it good, and then acid etched it according to ASTM standards. The floor had a really good profile. I applied the stain and it looked great. But when it came to neutralizing the floor, there was hardly any color there! What did I do wrong!?!”

See what I mean? Based on what we've discussed, can you spot the error?

It's not the applicator's fault. For just about any other coating this would have been a superior concrete prep job. But what the applicator failed to take into consideration was the application itself. Acid stains react with that uppermost layer of concrete. When the floor was acid etched, most of the reactive layer was already burned away.

Another example:

“I just can't understand what went wrong. We're always really good about prepping the surface. I've been doing coatings for years and we always make sure and get a real good surface profile. We clean the floor, making sure to degrease and scrub out any oil spots, scrape everything up real good. We always take an orbital floor grinder and grind down to make everything nice and even. But when we applied the acid we got no reaction at all? What went wrong?”

Starting to get the picture? Again, not an intentional error, but an error nonetheless. Get too aggressive with the concrete and you literally strip away the very stuff you need for a good acid stain reaction to occur.

How about this one:

“This just doesn't make sense. The concrete is practically brand new. I mean, it's had a few months to cure, so that shouldn't have been the problem. The concrete looked great. We knew enough not to acid etch the floor since we were using an acid stain. So we took a floor machine and scrubbed the whole surface real good with a mild cleanser. We rinsed it real good, several times actually, just to make sure there was no soap film or anything left behind that might react with the acid stain. The color went down beautifully. But when we neutralized, all of the color literally washed off. It was like we never even stained at all!”

This one might be a little harder to spot. While it's true that fresher concrete is usually a better candidate for an acid stain, there can often be a hidden danger here. A surface sealer. Surface sealers are sometimes sprayed down by the concrete crew to help keep moisture in the slab so that it can achieve a good hard cure. Surface sealers are often used in drier, hotter areas, for reasons that should be obvious. But surface sealers can also deflect coatings as well as stains.

The solution in this case? Well... get ready to go slightly against the grain. But just slightly.

Before we talk about the solution for this one let me just state that a very simple test can help you tell if a surface sealer is present. Just sprinkle some water on the surface. If it spots up and sinks in you're usually okay. If it just beads you've probably got a surface sealer.

Okay, that solution: In this case you actually MAY need to acid etch the surface in order to break up the sealer and remove it. If you have to do this use only a VERY LIGHT CONCENTRATION. You don't want to burn away that reactive material. But before you do that, try using any common surface stripper. Scrub it in with a floor machine, rinse and allow to dry. You should be good.

So What do you Recommend?

Just clean the floor real well. Use common sense and remove any adhesives, degrease and scrub any oil spots, etc. If the surface looks uneven or pitted, or if there are marks on the slab from the builder, or spots where carpet adhesives, tape marks or glues have been, then you may want to consider just laying a good overlay and staining that. Overlay material usually stains very very well. Otherwise, just let the concrete and the acid stain work together.

Some Insurance

Here's a surefire way to tell exactly how your floor is going to react. Actually stain it. But only in a 1' X 1' square. After you've done your cleaning, degreasing and rinsing, use some poly tape to tape off a small square (a closet is a good spot) and actually apply some stain. Go on to your next job and leave it overnight. When you come back the next day (don't go more than a day) wipe it with a rag dipped in ammonia water (wear gloves). You'll know right away what kind of color burn you are going to get.

Was this information helpful? I certainly hope so. You can learn all about acid staining floors and more in The Book of Decorative Concrete Coatings. We cover every aspect of acid staining, as well as all kinds of other popular decorative concrete coatings.

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Is it really necessary to prep concrete?

So, is it really necessary to prep concrete to receive a decorative coating?

The answer is a resounding… yes. Don’t let some products fool you. While there are a small handful of “green” or “odor free” products that will clean the surface (they mostly degrease and provide a very light etching) simply cleaning the concrete is only half the battle.

I take that back… cleaning the concrete is probably only about one third of the battle.

It makes sense: if you are going to apply a decorative concrete coating, the surface of the concrete should be clean and free of debris. Check any product label, they will all state this very clearly. But clean concrete – even concrete that has been degreased, scrubbed and pressure washed – is just the beginning. Here is why:

Concrete has a natural porosity, an ultra fine network known as the “capillary network” that is formed when the cement paste is introduced to water. As we all know, concrete hardens in the presence of water. This is known as “hydration”. Hard and durable concrete is good. But when it comes to applying a decorative concrete coating, it is the surface of the concrete that comes into question.

When a concrete surface is “floated” (the process by which latent water is brought to the surface and the aggregate tamped down to provide a smooth finish) a lot of the “cream” is brought to the top where it dries. This creates a kind of skin that is actually very attractive and smooth. But this smooth surface does not allow coatings to “key” in.

Simply put, the surface needs to be roughed up. And the best way to accomplish this is by acid etching or mechanically prepping.

Acid etching involves the use of muriatic acid (read precautions, be very careful) diluted with water. Use a common sprinkling can (the kind used in gardens) to wet the entire surface of the slab. Have a partner scrub the acid/water mixture in using a synthetic bristle broom. And keep the surface wet; acid that dries on the surface will create delam problems. Allow the acid to sit for a few minutes and then rinse with an ammonia/water mixture. Rinse very well and allow to dry.

Mechanical surface prep works in a similar fashion. This method incorporates the use of surface grinders to floor machines fitted with either diamond grinders or aggressive scuffing pads, depending on how much “roughing up” is required.

In both cases, the roughed-up surface of the concrete should feel like sandpaper. Your concrete is now degreased, washed and properly prepped to receive any decorative concrete coating.

Was this information useful? Find LOTS more tips and instructions in The Book of Decorative Concrete Coatings. Now taking pre-orders!