Sunday, July 12, 2015

There's No Rock Like a Faux Rock





In case you've been wondering why I haven't posted about anything I've been doing lately. That's because I've been too busy doing it to write about it. I've been making faux rocks.










Hubby called home one day and asked what I was doing. "Making rocks," I replied.

"Breaking rocks?" he asked.

"No, making rocks."

"You're making what with rocks?"

"I'm not making anything with rocks, I'm making the rocks."

"I guess you have to be there to understand that one," he sighed.



Maybe so. But I've been considering this for a long time, since I first saw a woman demonstrating it on a water garden forum years ago. Then, after we built our last pond partially above ground, I wondered if I could make rocks to go around the cinderblock wall. We used an angled faux stone, but it never looked right, and had to have stones on top of it in order to hide the liner. So that became my goal.

This is not going to be a tutorial on how to make faux rocks, but tips on making them so you can avoid some of the mistakes I made. There are plenty of tutorials online; in fact, that's where I learned; that and looking at a lot of real rocks for inspiration. My favorite tutorials are youtube videos by moore79 here. This is the first in his series, although it is really the second step. He built the base for his rock in the next video. I love his accent, but mainly I like the method he uses to make the rocks. A couple of things though if you follow his directions, especially if you are a beginner at working with cement, like me.

As you can see, the title of the first video is mortar mix, that is - making mortar mix. At the very beginning, he says he is "going to show how to mix up some cement, (unintelligible) mortar." So let's start with some definitions. Cement is the powder used to make both concrete and mortar. Concrete is made of cement, sand, gravel and water. Mortar is made of cement, a fine sand, and water. Here, he is making mortar. If you have access to a concrete supply company, you can probably buy the sand he used to make this mortar. If, however, you are like me, and your only choices are Home Depot and Lowes, your choices of sand will be All Purpose Sand and Playsand, and neither are fine enough to make mortar like his. However, both stores sell a prepackaged mortar mix that will have the same texture as his. All you add is water.

Now let's talk water. He puts a lot of water in his mix. Too much, in fact. Scroll down to the end of the video and you can see how soupy it is. Even after letting it slake for a couple of minutes, the mixture will never absorb that much extra water. However, in his next video, his mixture has magically become the right consistency. I STRONGLY advise you to measure your water if you are inexperienced. When putting the correct amount of water with the mortar mix, it will seem too dry to work and you'll think you need more water. Trust me, if you add more, it will become too soupy as you work it all in, and then you can't use it. At first it will seem to be the right amount of water, and as you work it, it will become too thin. Instead, don't put all the mortar mix in to begin with. Save out a gallon or so. The remaining mix and your water will mix better, and you'll see it change from dry and hard to work, to too wet. But then you add back that gallon of dry mix, and it mixes in to form the right consistency.

What is letting it slake? It is like a refreshment period for the mixed concrete or mortar, where it absorbs the extra water in the tub and becomes smoother. It just takes a few minutes for this. Then mix it again, and it's good to go.

In the video, he uses powdered concrete color. Those are not stocked at Home Depot or Lowes, at least not at any near me. You can order it from Home Depot. What is available at these stores is liquid concrete color. It's the same colors as the powder, but it takes much more than a few tablespoons to get the same color as with the powder. We happened to have a box of the powder and that was the only difference I found. A tip if you use the liquid: Add the color before the water. If you add it after the water, or after the mortar is mixed, it goes straight to the bottom and is harder to mix in.

Mr. Moore says somewhere in the videos that rock making is so easy that you really can't do it wrong. The man at Home Depot asked if I was out to prove him wrong, and I did, as you can see in the above photo. And those were made after making a lot of practice rocks and throwing the rejects in the rock base pile. For my first project, I wanted to make a three-sided rock to fit over the cinder block pond wall. Those vertical sides were a killer, especially when I didn't have the consistency right. Too loose, and it just slid off the form, even with reinforcing wire. Much, much easier to make flat ones at first, and it helped me see what it took to make it look more rock-like.

At the bottom of the deck steps, grass wouldn't grow where we stepped all the time. I had been trying to think what to do there, so it was a good place for more practice on creating rocks, realistic rocks if possible. I dug down five or six inches, put down a few inches of all purpose sand, and then an inch or two of concrete (for strength), and then the mortar mix to form the rocks. I wanted it to look like separate rocks fitted together, and after some trial and error, found that the best way to do that was to form the final mortar layer into separate rocks.  I put the top mortar layer on top of the wet concrete layer and pressed it in.  I put enough concrete layer to make just a few rocks on it before it set up.  Since it was going to be stepped on a lot, I wanted the strength of the concrete and wanted to make sure the layers didn't separate.

The first rock.  The concrete bottom layer is the length of the step.

After the first row was done, I let it dry completely before digging out the area for the next section.  As you can see, the rock is much lighter after drying.  I'll explain more about that later.

First stone in the next section.  It looks like I started in the middle, but really it was because I didn't mix enough mortar.

Finished with a rock on each side.


In the video, Mr. Moore says something about not mixing the color completely so there is a natural looking variation in the rock color.  I did that with the first rock, but the "variation" was the terra cotta I put in, and the gray of the mortar mix.  When dried, the gray looked just like concrete gray.  On the next one, I mixed in the terra cotta completely, and put in a little black and mixed it just a little.  The problem there was that black goes a long way, even with this liquid color.  Every bit of the rock had swirls of black in it, and if I worked it too much, the rock was all black.  So I used a different method for mixing the colors.

I mixed the mortar mix as usual.  Then scooped out a few cups and put that in a separate bucket.

(In case you are wondering why I have a tub inside a wheel barrow, it's because my wheel barrow has a hole in it and I got tired of trying to place a cup in just the right place under it in order to catch the leaking mortar.  So I bought a tub that fit inside it.)

Added black or charcoal color to the mortar in the bucket.


Into the uncolored mortar, I mixed in the lighter color completely, in this case it was Buff.  Then added a darker color.


Mixed in the second color just a little.


While it was slaking, I mixed the concrete mix and put it in. This side was deeper than the other, and I only had enough concrete mixed for one rock.

After putting the colored mortar into a rock shape, drop some of the black mortar on it.


Smooth the rock and add rock-like creases and texture.  I like using a crumpled plastic shopping bag to smooth it.


The more you work the rock, the more water will come to the surface. Don't worry about that, as long as the mortar holds its shape. The water will absorb again or dry when you leave it alone.

A couple of hours later, dried and showing more detail.


Now about the color fading. It will lighten a little as it dries. But you can see on mine that it did more than lighten; it effloresced. Efflorescence is a crystalline mineral that comes out of concrete after it dries. There are several things that cause it, but number one is mixing with too much water. I definitely had those first three rocks too wet. Not soupy wet, just saggy wet, but that was enough. The good news is that the concrete color can be used on them again after they are dry, and some rocks even looked beter after they were re-stained.

On the video, Mr. Moore says to dig out around the bottom before adding the top layer to the rock. I dug out my area, but then filled it in with the base concrete and didn't dig out more for the top mortar layer. Those edges bother me, but hopefully, the grass will grow up and over it and no one will notice it. But learn from me, and dig out around the edges so the rough edge can be buried afterward.

Soooooo, after I finished these flat rocks, I thought I was ready for something with a little height.

I wanted to move my mailbox to the other side of the driveway. The mail carriers don't pull back in the street after delivering the mail, but drive through the edge of my yard, which creates a muddy rut that I have to mow and edge. Moving it to the other side will keep that to a minimum, especially if there is no yard to drive through.



I wanted a rock planter, and I wanted it to look like our native white rock. For this, I used white cement. I started with white portland cement and mixed it with playsand at a 1:2 ratio. I tried 1:3, but it was too grainy. Fine sand would have worked much better. I really didn't like the consistency after working with the mortar mix. So after finishing off that bag, I tried a bag or white masonry cement and it worked much better. It was stickier and kept its shape better. I still used the 2:1 ratio, and mixed it the same as the mortar mix.

I didn't have time to take photos along the way with this one. When the mortar dried, it was more white than I wanted, but I thought some aging would take care of that. I made a thin mixture of water and black color and dribbled it along the edges of the creases and crevices. This photo was taken right afterward, and it lightened considerably when it dried.


It was still a little too white, so this evening, I mixed a little buff color and poured it over the entire thing. Except for the areas where it puddled (and that will be gone tomorrow), the color looks good. That probably means it will be lighter tomorrow and I may have to do another color rinse.





So now I'm ready to tackle rocks that will wrap the top of the pond wall.

Thanks for hanging in through this. I know it is a long post.

3 comments:

Kate said...

Wow, there is a lot to making fake rocks.

MartiDIY said...

Yes, lots of steps, hard work, and then pretty much stuck with it. I did tell Hubby if he didn't like it when I was finished, that I would break it out. So far, he doesn't hate it.

Tired Teacher said...

Interesting. I doubt I would tackle anything like that.