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- Written by: Tom Ralston Concrete
This volume of Decorative Concrete Master Q&A is inspired by a question that we received from concrete contractors in Australia about how Tom Ralston Concrete has used seaweed and other natural materials in decorative concrete. In this Q&A Tom references a project to highlight the process and use of custom made seaweed molds, check out the project here. Tom then goes into further detail about not only using seaweed in decorative concrete, but also the general aesthetic, function, utility and cost of using natural materials in decorative concrete jobs.
Tom, we are concrete contractors in Australia. I have been asked to see what we can achieve with seaweed. Are you willing to provide me with the process you use?

Tom Ralston: The way we made our seaweed molds was to harvest live seaweed from the Monterey Bay, bring it back, wash all the saltwater off of it, and make rectangular or square clay trays. We then embossed the seaweed into the clay - the clay was about a half an inch thick. If the seaweed were long strands, we had long rectangular frames filled with clay. If they were more square we'd have a square frame filled with clay. Then we rolled paint rollers on top of the seaweed to give it its impression. The next day we filled the clay molds with poly-urethane rubber and let that dry and cure, and it became a stamp - so that's how we made our stamps.
How can the use of natural materials add to the aesthetic and function of decorative concrete?
Tom Ralston: If you're talking about flagstone or rock, then that's pretty easy. Flagstone or rock is a natural material. If you make concrete that harmonizes in color with some of the elements of color in the rock or the stone or the flagstone, it will certainly enhance your concrete work. The other natural material you could use, that some may consider, are acid stains - which are made from iron-oxides from the earth, from minerals. The iron-oxide is turned into an acid. Myradic acid and water are used as a vehicle to take the iron oxide and transport them into the concrete matrix, and hence stain them. So that's another example of what I might consider, or someone might consider, to be a natural material - the acid stain. Again the other natural materials would be stone; however, placing wood in a close proximity of concrete can also be considered the use of a natural material.
Can you give examples of when you used seaweed or other natural ocean materials in your concrete?
Tom Ralston: Yes, we used seaweed in a client's living room floor. The client wanted to have something that was ocean-themed. We started talking about how he lived right on the beach in Santa Cruz, and the conversation ended up at, "What would happen if there was a giant tidal wave? And what would your floors look like?". And I said, "Well the floors would probably look like they have driftwood and seaweed and other flotsam from the ocean that would indicate that there was a serious tidal wave, or flooding from the ocean's swells." That conversation was the genesis for this project.
So we made special molds, like I described earlier with the seaweed molds, and we stamped the client's floor. The floor was only ⅜" thick, ½" at the thickest point. And the molds, with the bulbs on the seaweed, were over a ¼" themselves, so it was almost to the point where the bulbs from the seaweed molds were going down to the floor, the bare floor, but it didn't do that. And then afterwards, we acid stained these pieces of seaweed that were stamped into the floor.
My associate Bill Goff did a technique that he came up with called a dry-rub, and it's where you take just little bits of acid on a rag and rub it in, very gingerly and carefully, rather than spraying lots of liquid. So we used Bill's dry-rub technique so that the top parts of the seaweed profile, the higher parts, got one color and then down in the lower parts, the trough, there was another. The seaweed bulbs became a dark Padre Brown and some of the leaves were a light Antique Amber, just like you see regular seaweed.They had some parts that were darker than others so it looked very natural.
The other job that we used the seaweed was for a memorial out on West Cliff Dr. in Santa Cruz, CA for Robert 'Wally' Waldemar. We had his brass plaque at the top, and then the seaweed wrapped around the face of a rectangular piece of concrete. It had a top that tilted down so you could read the plaque that much more easily. And it said, "Robert Wally Waldemar - The Ocean Was My Life and My Life Was The Ocean". So it was really cool. The seaweed for this job got acid-stained much in the same manner as I described earlier using the dry-rub technique. Then around the seaweed leaves, both for this memorial and for the previous project, we acid stained a green blue color - similar to the color of the Monterey Bay, the body of water that these jobs overlook here in Santa Cruz.
What is the process you used to accomplish the use of seaweed or other natural materials in the past?
Tom Ralston: It's basically just stamping concrete with the seaweed mold. We've done similar things with other natural materials - we've put Mexican pebbles and turned them up on edge so they look like dorsal fins. And we've turned rocks on their sides so that there could be patterns that flow in a serpentine fashion, some of them look like schools of fish swimming around a fountain, we've done that with bands. It's great not only used as a band looking like dorsal fins, but also to incorporate a functional drain below. So most of the rocks are grouted in, but where the drain is they're not grouted in so that it functions as a drain yet looks seamlessly incorporated into the pattern. So you have this aesthetic function and a function of utility - that being the drain.
What is your favorite aspect of using materials like seaweed in your concrete jobs?
What is the cost benefit of using seaweed or other natural materials in concrete?
Tom Ralston: I don't think there is a cost-benefit. I think that when you start incorporating art like this into concrete, the costs rise. So there's no real cost-benefit of using seaweed or other natural materials in concrete, unless there's a situation where someone wants very expensive stone imported from Italy, but instead they opt to use a really nice decorative concrete that actually is less money. Some of the stone from Greece and Europe, England, Italy, France - they have some outlets and vendors that use real cobblestone from the streets of Europe. I mean that's hugely expensive, so you could compete with that kind of product using an artistic decorative concrete. But for the most part, these kind of artistic applications are not cost beneficial.
What are the most common applications for seaweed or other natural materials in decorative concrete?
Alright folks, that's it for this edition of Decorative Concrete Master Q&A, join us next time for more insider knowledge from decorative concrete master Tom Ralston. We post these Master Q&A's on the first and third thursdays of each month.
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- Written by: Tom Ralston
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- Written by: Tom Ralston
I have been reflecting lately about teaching seminars for decorative concrete. I started doing seminars for Granite Rock at the show grounds in Watsonville California. The Granite Rock demonstration focused on how to color, stamp and texture decorative concrete. This was in 1995.
I remember a few years later I was asked to do a bonifide seminar by the American Society of Concrete Contractors in Dallas Texas. For the first time I had to speak on a podium and then go out in the field and give a demonstration. This particular seminar was on techniques for Acid Staining Concrete and decorative saw cutting. As I watched another person give his talk I became more and more nervous looking out to the audience of approximately 50-people as I watched another person give his talk. I was supposed to do my presentation at 10:30 a.m. but the speaker before me was running over by about 40 minutes. Because of this run over on time my presentation was pushed to after lunch.
As I sat waiting for my lunch to arrive my nervousness turned to anxiety. When the food showed up I couldn’t eat a thing, in fact I was actually fake eating so that people wouldn’t think there was something wrong. (I might have asked where was the hungry dog under the table was at that moment). When it was my turn to speak the nervousness lasted about 5-minutes. I even had a “quasi-heckler” in the audience and I was able to handle him fairly well. That was over 19 years ago. I’ve been teaching seminars for years.
I do love teaching and sharing information. Having people that quest for knowledge like I do is exiting. It is a mutual passion and both student and teacher can feed off each other. I love sharing about my trials and tribulations in the world of decorative concrete and hope that my information is of value. I do think I am sharing valuable information. I have made so many costly errors in every aspect of construction and try express that in my seminars and lectures. Knowing that I’ve helped someone see the art in concrete work is so rewarding to me.
Concrete is so versatile. I don’t think a lot of people see that. Hopefully my seminars and lectures will help them realize that they have a greater scope of what concrete can do to beautify a landscape, a hillside, a property, a commercial building. They could even add a glow with a Lumi Lumi Concrete applications.
The real joy comes when I see someone that attended one of my seminars and they have done something really cool with what they learned. Or they come up to me and say they still remember my seminar and how it made a lasting impression on them. I am proud and honored that I could be an inspiration to them.
I also am on the Board for the Construction Energy and Management course taught at Cabrillo College and have been for seven years. Chuck Mornard is the Chairperson. This helps students find employment in the broad spectrum of opportunities available in the construction industry. The program also provides continuing education for those already employed in the construction industry.
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- Written by: Tom Ralston
Confucius say:
"While sometimes it is good to sip, at other times it is Great to Guzzle"
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- Written by: Tom Ralston
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- Written by: Tom Ralston
This year Tom Ralston Concrete entered one project in the best specialty concrete category and won first place. The 2013 award follows Tom Ralston Concrete's 2012 awards for Best Cast in Place as well as Best in Show for the same project. The Cygnus media group called Tom Ralston after the winners were chosen and asked if he wouldn't mind doing an interview at the 2013 World of Concrete. This video has Cynuns' Roger Mann interviewing Tom Ralston for the second year in a row.
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- Written by: Tom Ralston
So it all started with an e-mail in February of 2007 from a woman who saw our "Rockview" floors on our Website. The concrete floors and walls she saw are in a house that overhangs the Monterey Bay on the California Coastline. She said that she had seen "veins" filled with aquarium sand, beach glass, and various seashells and she said that she "absolutely loved them." The catch was, she wanted our company to replicate this floor over 3800 miles away-- in Panama-- Bocas Del Toro to be exact which is on the Caribbean side of Panama. I was excited at the prospect thinking Tropical Island, great surf, unique and colorful floors...to a surfing concrete contractor from Santa Cruz, California this all sounded like a slice of heaven on earth to me.
Next came probably the hardest part of the venture: pricing and the logistics. What would it be like to work with the native Panamanians? How long would it take to construct our floors on a small island in a Third World Country? How difficult would it be to get the "hazardous" materials to Panama? I have had enough bouts in the United States with Hazardous Materials Agencies when it came to acid staining. We always make sure that we use baking soda or ammonia and copious amounts of fresh water to rinse with Acid Stains so that all of the tests will pass and come up neutral. How would we deal with shipping Hazardous Material to Panama? How much should we charge?