A Sticky Business
In high school, one of my friends got into a really big ‘crafting’ phase. Decorative plates, cute picture frames … if she saw it on a crafting website, it was on her work table that night. During this phase, she swore by Mod Podge, a glue-like substance. “It’ll stick anything to anything,” she announced proudly, as she lead a crafting party. I learned soon afterward that she was right, because I managed to glue my fingers together with it.
Tackifiers will probably not glue your fingers together, and I wouldn’t recommend using them for crafts, but they do work in nearly the same way as Mod Podge. They’re sticky substances used to get soil, dust or mulch to stick together, in order to prevent erosion and washout during construction or hydroseeding.
Since you’re reading Soil Erosion and Hydroseeding magazine, you’re likely familiar with tackifiers and the wide range of products you have available to you. You may swear by guar, or you might make your own mix of various types of tackifiers. Regardless of whether you’re new to the world of hydroseeding and soil stabilization or a seasoned veteran in the field, now is a good time to reconsider the tackifiers you use, since every job has different requirements.
The first thing to address is, of course, what kind of tackifiers are out there in the world. And, quite frankly, there are lots. Rosins, hydrocarbons, guar, acrylic, plantago, PAM … even soybean oil; these are just some of the options that are available when selecting a tackifier.
Obviously, that’s too much information for one article. For now, let’s narrow it down to the most popular: guar, plantago and PAM—which stands for polyacrylamide (anionic).
Guar is a plant-based tackifier, made from the seeds of the cluster bean plant from India. It’s made into a water-soluble paste, called guar gum, which is slippery when wet, and sticky when dry. This trait makes it a favorite among hydroseeders. The slippery aspect means that it goes through a sprayer easily, and the stickiness means that the seeds stay intact. With a reasonable price tag and natural ecofriendliness (since it is derived from a legume), this was the most popular tackifier for quite some time.
Like guar, plantago is also a plantbased tackifier. This one is made from psyllium—the protective outer coating of the plantago seed. It’s one of the least expensive tackifiers available, since plantago plants are found all over the world. When wet, plantago is a mucilloid substance, which is a fancy way of saying that it gets sticky when wet, but dries to a relatively firm state, making it useful for both hydroseeding and dust control.
The last of the ‘Big Three’ is PAM, which works a little differently than the other two. Unlike guar and plantago, PAM is a chemical-based tackifier. You may hear some debate about whether it really is safe to use, but that’s in part due to the confusion between anionic PAM and cationic PAM. Cationic PAM has been proven to be highly toxic to aquatic life. Anionic PAM, the one used in soil stabilization and dust control, is EPA-approved and biodegradable, so there’s no need to worry about it harming any resident sea life.
PAM’s non-organic source isn’t the only difference between it and its organic counterparts. It also doesn’t have the ‘sticky’ qualities of guar or plantago. Instead, it flocculates the soil, which is a process of contact and adhesion of particles to form larger particles (called flocs). This makes the soil heavier, which means that it’s more difficult to displace. To refer back to my craft analogy, if guar and plantago are Mod Podge, gluing the soil into place, then PAM is closer to papier-mâché: laying saturated piece over saturated piece until they stick together.
While the Big Three are still the main ones used in most hydroseeding and soil stabilization work, there’s another type of tackifier that’s been growing more popular over the past few years: acrylic-based tackifiers. Acrylic, like PAM, is made from chemical polymers. However, while PAM makes soil heavier, acrylics are chemically engineered to attract soil particles to the polymers like a magnet, and bind them together. And, while acrylics tend to be water-based for easier spraying, they do not rely on water to become sticky. That means that the area is more water-resistant than it would be with an organic tackifier.
But, for all of the fuss over different tackifiers and their chemical makeup or organic compounds, there’s no denying that they all do the same job at the end of the day: they make things stick together. So does this mean that you have free reign to use whatever tackifiers you like?
The answer to that is yes, and no.
Yes, you can use any of these tackifiers to bind soil and mulch. No, they won’t all work the way you want them to. When picking your tackifier, the conditions of the area, the season, the particular project and drying—or curing—time of your chosen tackifier all need to be considered before getting to work.
For instance, if you just need everything to stay in place until your grass seeds start to germinate, then plantago is likely going to be your best bet. It’s cost-efficient, and it gets the job done. It also tends to be the favored tackifier of government-issued jobs, like the ones K-ler Land Works in Prescott, Arizona, gets from the Arizona Department of Transportation (ADOT).
“We usually go with plantago, since that is what’s called out on the ADOT and government jobs,” says Stella Koehler, who runs the hydroseeding business with her husband, Eric. “Another one we use is called PT-Tac, which is basically a premium plantago.”
K-ler’s work is primarily focused on restoring forest areas, such as the Coconino National Forest. Due to regulations, the area cannot be sprayed with too many chemicals. The plantago and PT-Tac mixes the company uses have an organic wood fiber base. “They’re clean and paperfree,” says Koehler. “It’s organic, and the state agencies are aware of that. It makes sense; if you’re going into forests, wanting to re-seed and revegetate areas that have been disturbed, then how counterproductive would it be if you put down something that was detrimental to the environment?”
If a client has a specific tackifier to use, then obviously, no further thought needs to go into it. But things aren’t quite so cut-and-dried if you’re choosing your own tackifier. Jack Eaton, an erosion-control specialist who heads up Filtrexx Northeast Systems in Goffstown, New Hampshire, has a list of factors to consider before he chooses a tackifier for each job.
“When I explain this to people, I tell them the things I ask myself before a project: What seed am I going to use? How soon is it going to germinate? What kind of conditions are going to be experienced in that period of time? That really determines what I’ll use for a tackifier,” he says.
“We grow a lot of native grasses here, so many of our applications will be up in a couple of weeks. Since we’re going to get germination in such a short amount of time, we have a wider range of tackifiers to use during growing season,” Eaton adds. “As we approach the end of our growing season, which is somewhere in mid- to late-October, we need to start thinking about tackifiers that last longer and provide more erosion control.”
As Eaton says, different jobs require different tackifiers. When restoring forests, something like plantago may work. But, if you’re going to need the soil to stay put for a few years, then PAM may be your best bet.
It could also pay to step outside of the Big Three for your projects. Acrylic tackifiers, for instance, tend to work best in areas prone to big rainstorms.
“Organic tackifiers work well during light and moderate rain events,” says Chris Rider, cofounder of DirtGlue, an acrylic-based tackifier. “If there is time to dry—or at least partially dry—in between rain events, then they’ll work well. But during very heavy or continuous rain events, these products become saturated to the point that they soften and begin to move downslope with the water. They can lose their tackifier effect when it’s needed most.”
He says that the acrylics in DirtGlue are not as prone to being washed out by heavy rains, once it has cured. “It will not soften or lose its bonding capability. It also will not move downslope in heavy or continuous rain events, regardless of how heavy they are or how long they last,” he adds.
The texture of your local soil is also an important factor in what sort of tackifier you’ll want to use. Sandy soil doesn’t bind well with PAM. As mentioned earlier, PAM saturates soil particles and lays them on top of each other. This requires particles to be electrically charged, but sandy soil doesn’t have enough charge for PAM to saturate the particles. In this case, you’d have to find a different tackifier. But, in areas like Eaton’s in New England, the soil could change altogether, depending on the season.
“Here in New England, as we get into the fall and early spring, our soil moisture goes way up. So we’re dealing with a little bit of a different situation than you have in other parts of the country, where soil moisture content stays fairly constant,” Eaton says. “Something acrylicbased doesn’t have a chance to cure in those conditions, but it works extremely well during the summer or when the soil is kind of dried up.”
Costs are also a major point of consideration. Hydroseeding and hydromulching can easily become very expensive, so making sure that you get the most amount of product per square foot covered is something which needs to be considered—both for your client and for your own pocket. Eaton, for example, uses DirtGlue during the dry season. It costs more than plantago, but it allows his workers to get more acreage out of a tank by using less fiber in their mix. Ultimately, that saves him money.
It’s good to be informed about the wide range of tackifiers you have at your disposal, but it can easily become overwhelming to the new hydroseeding professional. So which one should you try first?
Koehler advises starting simple. “I would start with plantago,” she says, “because it’s more cost-effective, and it’s readily available. Plus, it’s all-natural and better for the environment.”
That said, a little preliminary research goes a long way. If you buy a lot of plantago and it doesn’t work in your area, then that’s a waste of money. Ask other local professionals what they use. If you don’t know any personally, you could always visit forums and websites dedicated to hydroseeding. And don’t be afraid to experiment, no matter how long you’ve been in the business.
It may take some trial and error to find your Mod Podge of a tackifier, and you may never swear by one product alone. But, as you’re mixing your next slurry, whether it’s your first or one-hundred-and-first, take a moment to ask yourself and think about whether it will “stick anything to anything.”
If you’re as confident about your mix as my friend was about Mod Podge, then you’ve found the right tackifier. Just take care to keep your fingers from getting glued together.